/**
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.apache.tez.dag.api;

import java.lang.reflect.Field;
import java.util.Arrays;
import java.util.Collections;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import java.util.Set;

import org.apache.tez.common.annotation.ConfigurationClass;
import org.apache.tez.common.annotation.ConfigurationProperty;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.apache.hadoop.classification.InterfaceAudience.Private;
import org.apache.hadoop.classification.InterfaceAudience.Public;
import org.apache.hadoop.classification.InterfaceStability.Unstable;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.util.Shell;
import org.apache.hadoop.yarn.api.records.LocalResource;

import com.google.common.annotations.VisibleForTesting;


/**
 * Defines the configurations for Tez. These configurations are typically specified in 
 * tez-site.xml on the client machine where TezClient is used to launch the Tez application.
 * tez-site.xml is expected to be picked up from the classpath of the client process.
 * @see <a href="../../../../../configs/TezConfiguration.html">Detailed Configuration Information</a>
 * @see <a href="../../../../../configs/tez-default-template.xml">XML-based Config Template</a>
 */
@Public
@ConfigurationClass(templateFileName = "tez-default-template.xml")
public class TezConfiguration extends Configuration {

  public final static String TEZ_SITE_XML = "tez-site.xml";

  private final static Logger LOG = LoggerFactory.getLogger(TezConfiguration.class);

  private static Map<String, Scope> PropertyScope = new HashMap<String, Scope>();

  static {
    Configuration.addDeprecation("tez.am.counters.max.keys", TezConfiguration.TEZ_COUNTERS_MAX);
    Configuration.addDeprecation("tez.am.counters.groups.max.keys",
        TezConfiguration.TEZ_COUNTERS_MAX_GROUPS);
    Configuration.addDeprecation("tez.am.counters.name.max.keys",
        TezConfiguration.TEZ_COUNTERS_COUNTER_NAME_MAX_LENGTH);
    Configuration.addDeprecation("tez.am.counters.group-name.max.keys",
        TezConfiguration.TEZ_COUNTERS_GROUP_NAME_MAX_LENGTH);

    Configuration.addDeprecation("tez.task.scale.task.memory.enabled",
        TezConfiguration.TEZ_TASK_SCALE_MEMORY_ENABLED);
    Configuration.addDeprecation("tez.task.scale.task.memory.allocator.class",
        TezConfiguration.TEZ_TASK_SCALE_MEMORY_ALLOCATOR_CLASS);
    Configuration.addDeprecation("tez.task.scale.task.memory.reserve-fraction",
        TezConfiguration.TEZ_TASK_SCALE_MEMORY_RESERVE_FRACTION);
    Configuration
        .addDeprecation("tez.task.scale.task.memory.additional-reservation.fraction.per-io",
            TezConfiguration.TEZ_TASK_SCALE_MEMORY_ADDITIONAL_RESERVATION_FRACTION_PER_IO);
    Configuration.addDeprecation("tez.task.scale.task.memory.additional-reservation.fraction.max",
        TezConfiguration.TEZ_TASK_SCALE_MEMORY_ADDITIONAL_RESERVATION_FRACTION_MAX);
    Configuration.addDeprecation("tez.task.scale.task.memory.ratios",
        TezConfiguration.TEZ_TASK_SCALE_MEMORY_WEIGHTED_RATIOS);

    Configuration.addDeprecation("tez.task.max-events-per-heartbeat.max",
        TezConfiguration.TEZ_TASK_MAX_EVENTS_PER_HEARTBEAT);

    setupConfigurationScope(TezConfiguration.class);

  }

  static void setupConfigurationScope(Class<?> clazz) {
    for (Field field : clazz.getFields()) {
      if (field.isAnnotationPresent(ConfigurationScope.class)) {
        ConfigurationScope confScope = field.getAnnotation(ConfigurationScope.class);
        if (field.getType() == String.class) {
          try {
            PropertyScope.put(field.get(null).toString(), confScope.value());
          } catch (IllegalArgumentException e) {
            throw new RuntimeException(e);
          } catch (IllegalAccessException e) {
            throw new RuntimeException(e);
          }
        } else {
          throw new RuntimeException(field.getName() + " is not String type, should not been annotated with "
              + ConfigurationScope.class.getSimpleName());
        }
      }
    }
  }

  public TezConfiguration() {
    this(true);
  }

  public TezConfiguration(Configuration conf) {
    super(conf);
    addResource(TEZ_SITE_XML);
  }

  public TezConfiguration(boolean loadDefaults) {
    super(loadDefaults);
    if (loadDefaults) {
      addResource(TEZ_SITE_XML);
    }
  }

  @Private
  public static final String TEZ_PREFIX = "tez.";
  @Private
  public static final String TEZ_AM_PREFIX = TEZ_PREFIX + "am.";
  @Private
  public static final String TEZ_TASK_PREFIX = TEZ_PREFIX + "task.";

  /**
   * Boolean value. If true then Tez will try to automatically delete temporary job 
   * artifacts that it creates within the specified staging dir. Does not affect any user data.
   */
  @ConfigurationScope(Scope.AM)
  @ConfigurationProperty(type = "boolean")
  public static final String TEZ_AM_STAGING_SCRATCH_DATA_AUTO_DELETE = TEZ_AM_PREFIX +
      "staging.scratch-data.auto-delete";
  public static final boolean TEZ_AM_STAGING_SCRATCH_DATA_AUTO_DELETE_DEFAULT = true;

  /**
   * String value. Specifies a directory where Tez can create temporary job artifacts.
   */
  @ConfigurationScope(Scope.AM)
  @ConfigurationProperty
  public static final String TEZ_AM_STAGING_DIR = TEZ_PREFIX + "staging-dir";
  public static final String TEZ_AM_STAGING_DIR_DEFAULT = "/tmp/"
      + System.getProperty("user.name") + "/tez/staging";

  /**
   * String value that is a file path.
   * Path to a credentials file (with serialized credentials) located on the local file system.
   */
  @ConfigurationScope(Scope.AM)
  @ConfigurationProperty
  public static final String TEZ_CREDENTIALS_PATH = TEZ_PREFIX + "credentials.path";

  /**
   * Boolean value. If true then Tez will add the ApplicationMaster credentials
   * to all task credentials.
   */
  @ConfigurationScope(Scope.AM)
  @ConfigurationProperty(type="boolean")
  public static final String TEZ_AM_CREDENTIALS_MERGE = TEZ_AM_PREFIX
      + "credentials-merge";
  public static boolean TEZ_AM_CREDENTIALS_MERGE_DEFAULT = true;

  @Private
  @ConfigurationScope(Scope.AM)
  public static final String TEZ_AM_USE_CONCURRENT_DISPATCHER = TEZ_AM_PREFIX
      + "use.concurrent-dispatcher";
  @Private
  public static boolean TEZ_AM_USE_CONCURRENT_DISPATCHER_DEFAULT = false;
  
  @Private
  @ConfigurationScope(Scope.AM)
  public static final String TEZ_AM_CONCURRENT_DISPATCHER_CONCURRENCY = TEZ_AM_PREFIX
      + "concurrent-dispatcher.concurrency";
  @Private
  public static final int TEZ_AM_CONCURRENT_DISPATCHER_CONCURRENCY_DEFAULT = 10;

  /**
   * Boolean value. Execution mode for the Tez application. True implies session mode. If the client
   * code is written according to best practices then the same code can execute in either mode based
   * on this configuration. Session mode is more aggressive in reserving execution resources and is
   * typically used for interactive applications where multiple DAGs are submitted in quick succession
   * by the same user. For long running applications, one-off executions, batch jobs etc non-session 
   * mode is recommended. If session mode is enabled then container reuse is recommended.
   */
  @ConfigurationScope(Scope.AM)
  @ConfigurationProperty(type="boolean")
  public static final String TEZ_AM_SESSION_MODE = TEZ_AM_PREFIX + "mode.session";
  public static final boolean TEZ_AM_SESSION_MODE_DEFAULT = false;

  /**
   * Root Logging level passed to the Tez app master.
   *
   * Simple configuration: Set the log level for all loggers.
   *   e.g. INFO
   *   This sets the log level to INFO for all loggers.
   *
   * Advanced configuration: Set the log level for all classes, along with a different level for some.
   *   e.g. DEBUG;org.apache.hadoop.ipc=INFO;org.apache.hadoop.security=INFO
   *   This sets the log level for all loggers to DEBUG, expect for the
   *   org.apache.hadoop.ipc and org.apache.hadoop.security, which are set to INFO
   *
   * Note: The global log level must always be the first parameter.
   *   DEBUG;org.apache.hadoop.ipc=INFO;org.apache.hadoop.security=INFO is valid
   *   org.apache.hadoop.ipc=INFO;org.apache.hadoop.security=INFO is not valid
   * */
  @ConfigurationScope(Scope.AM)
  @ConfigurationProperty
  public static final String TEZ_AM_LOG_LEVEL = TEZ_AM_PREFIX + "log.level";
  public static final String TEZ_AM_LOG_LEVEL_DEFAULT = "INFO";

  /**
   * Root Logging level passed to the Tez tasks.
   *
   * Simple configuration: Set the log level for all loggers.
   *   e.g. INFO
   *   This sets the log level to INFO for all loggers.
   *
   * Advanced configuration: Set the log level for all classes, along with a different level for some.
   *   e.g. DEBUG;org.apache.hadoop.ipc=INFO;org.apache.hadoop.security=INFO
   *   This sets the log level for all loggers to DEBUG, expect for the
   *   org.apache.hadoop.ipc and org.apache.hadoop.security, which are set to INFO
   *
   * Note: The global log level must always be the first parameter.
   *   DEBUG;org.apache.hadoop.ipc=INFO;org.apache.hadoop.security=INFO is valid
   *   org.apache.hadoop.ipc=INFO;org.apache.hadoop.security=INFO is not valid
   * */
  @ConfigurationScope(Scope.VERTEX)
  @ConfigurationProperty
  public static final String TEZ_TASK_LOG_LEVEL = TEZ_TASK_PREFIX + "log.level";
  public static final String TEZ_TASK_LOG_LEVEL_DEFAULT = "INFO";

  /**
   * double value. Represents ratio of unique failed outputs / number of consumer
   * tasks. When this condition or value mentioned in {@link
   * #TEZ_TASK_MAX_ALLOWED_OUTPUT_FAILURES} is met, task would be declared as failed by AM.
   *
   * Expert level setting.
   */
  @ConfigurationScope(Scope.AM)
  public static final String TEZ_TASK_MAX_ALLOWED_OUTPUT_FAILURES_FRACTION =
      TEZ_TASK_PREFIX + "max.allowed.output.failures.fraction";
  public static final double TEZ_TASK_MAX_ALLOWED_OUTPUT_FAILURES_FRACTION_DEFAULT = 0.1;

  /**
   * Int value. Represents maximum allowed unique failures after which a task would be
   * declared as failed by AM. When this condition or the threshold mentioned in {@link
   * #TEZ_TASK_MAX_ALLOWED_OUTPUT_FAILURES_FRACTION} is met, task would be relaunched by AM.
   *
   * Expert level setting.
   */
  @ConfigurationScope(Scope.AM)
  public static final String TEZ_TASK_MAX_ALLOWED_OUTPUT_FAILURES =
      TEZ_TASK_PREFIX + "max.allowed.output.failures";
  public static final int TEZ_TASK_MAX_ALLOWED_OUTPUT_FAILURES_DEFAULT = 10;

  /**
   * int value. Represents the maximum time in seconds for which a consumer attempt can report 
   * a read error against its producer attempt, after which the producer attempt will be re-run 
   * to re-generate the output. There are other heuristics which determine the retry and mainly 
   * try to guard against a flurry of re-runs due to intermittent read errors 
   * (due to network issues). This configuration puts a time limit on those heuristics to ensure
   * jobs dont hang indefinitely due to lack of closure in those heuristics 
   *
   * Expert level setting.
   */
  @ConfigurationScope(Scope.AM)
  @ConfigurationProperty(type="integer")
  public static final String TEZ_AM_MAX_ALLOWED_TIME_FOR_TASK_READ_ERROR_SEC =
      TEZ_AM_PREFIX + "max.allowed.time-sec.for-read-error";
  public static final int TEZ_AM_MAX_ALLOWED_TIME_FOR_TASK_READ_ERROR_SEC_DEFAULT = 300;

  /**
   * Boolean value. Determines when the final outputs to data sinks are committed. Commit is an
   * output specific operation and typically involves making the output visible for consumption. 
   * If the config is true, then the outputs are committed at the end of DAG completion after all 
   * constituent vertices have completed. If false, outputs for each vertex are committed after that 
   * vertex succeeds. Depending on the desired output visibility and downstream consumer dependencies
   * this value must be appropriately chosen. Defaults to the safe choice of true.
   */
  @ConfigurationScope(Scope.DAG)
  @ConfigurationProperty(type="boolean")
  public static final String TEZ_AM_COMMIT_ALL_OUTPUTS_ON_DAG_SUCCESS =
      TEZ_AM_PREFIX + "commit-all-outputs-on-dag-success";
  public static final boolean TEZ_AM_COMMIT_ALL_OUTPUTS_ON_DAG_SUCCESS_DEFAULT = true;

  /**
   * Boolean value. Determine whether to log history events per dag
   */
  @ConfigurationScope(Scope.DAG)
  @Private
  public static final String TEZ_DAG_HISTORY_LOGGING_ENABLED =
      TEZ_PREFIX + "dag.history.logging.enabled";
  public static final boolean TEZ_DAG_HISTORY_LOGGING_ENABLED_DEFAULT = true;

  /**
   * String value. Command line options which will be prepended to {@link #TEZ_AM_LAUNCH_CMD_OPTS}
   * during the launch of the AppMaster process. This property will typically be configured to
   * include default options meant to be used by all jobs in a cluster. If required, the values can
   * be overridden per job.
   */
  @ConfigurationScope(Scope.AM)
  @ConfigurationProperty
  public static final String TEZ_AM_LAUNCH_CLUSTER_DEFAULT_CMD_OPTS =
      TEZ_AM_PREFIX + "launch.cluster-default.cmd-opts";
  public static final String TEZ_AM_LAUNCH_CLUSTER_DEFAULT_CMD_OPTS_DEFAULT =
      "-server -Djava.net.preferIPv4Stack=true -Dhadoop.metrics.log.level=WARN";

  /**
   * String value. Command line options provided during the launch of the Tez
   * AppMaster process. Its recommended to not set any Xmx or Xms in these launch opts so that
   * Tez can determine them automatically.
   * */
  @ConfigurationScope(Scope.AM)
  @ConfigurationProperty
  public static final String TEZ_AM_LAUNCH_CMD_OPTS = TEZ_AM_PREFIX +  "launch.cmd-opts";
  public static final String TEZ_AM_LAUNCH_CMD_OPTS_DEFAULT = 
      "-XX:+PrintGCDetails -verbose:gc -XX:+PrintGCTimeStamps -XX:+UseNUMA -XX:+UseParallelGC";

  /**
   * String value. Command line options which will be prepended to {@link
   * #TEZ_TASK_LAUNCH_CMD_OPTS} during the launch of Tez tasks.  This property will typically be configured to
   * include default options meant to be used by all jobs in a cluster. If required, the values can
   * be overridden per job.
   */
  @ConfigurationScope(Scope.AM) // TODO DAG/Vertex level
  @ConfigurationProperty
  public static final String TEZ_TASK_LAUNCH_CLUSTER_DEFAULT_CMD_OPTS =
      TEZ_TASK_PREFIX + "launch.cluster-default.cmd-opts";
  public static final String TEZ_TASK_LAUNCH_CLUSTER_DEFAULT_CMD_OPTS_DEFAULT =
      "-server -Djava.net.preferIPv4Stack=true -Dhadoop.metrics.log.level=WARN";

  /**
   * String value. Command line options provided during the launch of Tez Task
   * processes. Its recommended to not set any Xmx or Xms in these launch opts
   * so that Tez can determine them automatically.
   */
  @ConfigurationScope(Scope.AM) // TODO DAG/Vertex level
  @ConfigurationProperty
  public static final String TEZ_TASK_LAUNCH_CMD_OPTS = TEZ_TASK_PREFIX
      + "launch.cmd-opts";
  public static final String TEZ_TASK_LAUNCH_CMD_OPTS_DEFAULT =
      "-XX:+PrintGCDetails -verbose:gc -XX:+PrintGCTimeStamps -XX:+UseNUMA -XX:+UseParallelGC";

  /**
   * Double value. Tez automatically determines the Xmx for the JVMs used to run
   * Tez tasks and app masters. This feature is enabled if the user has not
   * specified Xmx or Xms values in the launch command opts. Doing automatic Xmx
   * calculation is preferred because Tez can determine the best value based on
   * actual allocation of memory to tasks the cluster. The value if used as a
   * fraction that is applied to the memory allocated Factor to size Xmx based
   * on container memory size. Value should be greater than 0 and less than 1.
   *
   * Set this value to -1 to allow Tez to use different default max heap fraction
   * for different container memory size. Current policy is to use 0.7 for container
   * smaller than 4GB and use 0.8 for larger container.
   */
  @ConfigurationScope(Scope.AM)
  @ConfigurationProperty(type="float")
  public static final String TEZ_CONTAINER_MAX_JAVA_HEAP_FRACTION =
      TEZ_PREFIX + "container.max.java.heap.fraction";
  public static final double TEZ_CONTAINER_MAX_JAVA_HEAP_FRACTION_DEFAULT = 0.8;

  private static final String NATIVE_LIB_PARAM_DEFAULT = Shell.WINDOWS ?
    "PATH=%PATH%;%HADOOP_COMMON_HOME%\\bin":
    "LD_LIBRARY_PATH=$LD_LIBRARY_PATH:$HADOOP_COMMON_HOME/lib/native/";

  /**
   * String value. Env settings will be merged with {@link #TEZ_AM_LAUNCH_ENV}
   * during the launch of the AppMaster process. This property will typically be configured to
   * include default system env meant to be used by all jobs in a cluster. If required, the values can
   * be appended to per job.
   */
  @ConfigurationScope(Scope.AM)
  @ConfigurationProperty
  public static final String TEZ_AM_LAUNCH_CLUSTER_DEFAULT_ENV =
      TEZ_AM_PREFIX + "launch.cluster-default.env";
  public static final String TEZ_AM_LAUNCH_CLUSTER_DEFAULT_ENV_DEFAULT =
      NATIVE_LIB_PARAM_DEFAULT;

  /** String value. Env settings for the Tez AppMaster process.
   * Should be specified as a comma-separated of key-value pairs where each pair
   * is defined as KEY=VAL
   * e.g. "LD_LIBRARY_PATH=.,USERNAME=foo"
   * These take least precedence compared to other methods of setting env.
   * These get added to the app master environment prior to launching it.
   * This setting will prepend existing settings in the cluster default
   */
  @ConfigurationScope(Scope.AM)
  @ConfigurationProperty
  public static final String TEZ_AM_LAUNCH_ENV = TEZ_AM_PREFIX
      + "launch.env";
  public static final String TEZ_AM_LAUNCH_ENV_DEFAULT = "";

  /**
   * String value. Env settings will be merged with {@link #TEZ_TASK_LAUNCH_ENV}
   * during the launch of the task process. This property will typically be configured to
   * include default system env meant to be used by all jobs in a cluster. If required, the values can
   * be appended to per job.
   */
  @ConfigurationScope(Scope.VERTEX)
  @ConfigurationProperty
  public static final String TEZ_TASK_LAUNCH_CLUSTER_DEFAULT_ENV =
      TEZ_TASK_PREFIX + "launch.cluster-default.env";
  public static final String TEZ_TASK_LAUNCH_CLUSTER_DEFAULT_ENV_DEFAULT =
      NATIVE_LIB_PARAM_DEFAULT;

  /** String value. Env settings for the Tez Task processes.
   * Should be specified as a comma-separated of key-value pairs where each pair
   * is defined as KEY=VAL
   * e.g. "LD_LIBRARY_PATH=.,USERNAME=foo"
   * These take least precedence compared to other methods of setting env
   * These get added to the task environment prior to launching it.
   * This setting will prepend existing settings in the cluster default
   */
  @ConfigurationScope(Scope.VERTEX)
  @ConfigurationProperty
  public static final String TEZ_TASK_LAUNCH_ENV = TEZ_TASK_PREFIX
      + "launch.env";
  public static final String TEZ_TASK_LAUNCH_ENV_DEFAULT = "";

  @Private
  @ConfigurationScope(Scope.DAG)
  @ConfigurationProperty(type="boolean")
  public static final String TEZ_CANCEL_DELEGATION_TOKENS_ON_COMPLETION = TEZ_PREFIX +
      "cancel.delegation.tokens.on.completion";
  public static final boolean TEZ_CANCEL_DELEGATION_TOKENS_ON_COMPLETION_DEFAULT = true;

  @Private
  @Unstable
  @ConfigurationScope(Scope.DAG)
  public static final String TEZ_AM_ONE_TO_ONE_ROUTING_USE_ON_DEMAND_ROUTING =
      TEZ_AM_PREFIX + "one-to-one.routing.use.on-demand-routing";
  public static final boolean TEZ_AM_ONE_TO_ONE_ROUTING_USE_ON_DEMAND_ROUTING_DEFAULT = false;

  /**
   * Int value. The number of threads used to listen to task heartbeat requests.
   * Expert level setting.
   */
  @ConfigurationScope(Scope.AM)
  @ConfigurationProperty(type="integer")
  public static final String TEZ_AM_TASK_LISTENER_THREAD_COUNT =
      TEZ_AM_PREFIX + "task.listener.thread-count";
  public static final int TEZ_AM_TASK_LISTENER_THREAD_COUNT_DEFAULT = 30;

  /**
   * Int value. Configuration to limit the counters per dag (AppMaster and Task). This can be used
   * to
   * limit the amount of memory being used in the app master to store the
   * counters. Expert level setting.
   */
  @Unstable
  @ConfigurationScope(Scope.AM)
  @ConfigurationProperty(type="integer")
  public static final String TEZ_COUNTERS_MAX = TEZ_PREFIX + "counters.max";
  public static final int TEZ_COUNTERS_MAX_DEFAULT = 1200;

  /**
   * Int value. Configuration to limit the number of counter groups for a DAG. This can be used to
   * limit the amount of memory being used in the app master to store the
   * counters. Expert level setting.
   */
  @Unstable
  @ConfigurationScope(Scope.AM)
  @ConfigurationProperty(type="integer")
  public static final String TEZ_COUNTERS_MAX_GROUPS = TEZ_PREFIX + "counters.max.groups";
  public static final int TEZ_COUNTERS_MAX_GROUPS_DEFAULT = 500;

  /**
   * Int value. Configuration to limit the length of counter names. This can be used to
   * limit the amount of memory being used in the app master to store the
   * counters. Expert level setting.
   */
  @Unstable
  @ConfigurationScope(Scope.AM)
  @ConfigurationProperty(type="integer")
  public static final String TEZ_COUNTERS_COUNTER_NAME_MAX_LENGTH =
      TEZ_PREFIX + "counters.counter-name.max-length";
  public static final int TEZ_COUNTERS_COUNTER_NAME_MAX_LENGTH_DEFAULT = 64;

  /**
   * Int value. Configuration to limit the counter group names per app master. This can be used to
   * limit the amount of memory being used in the app master to store the
   * counters. Expert level setting.
   */
  @Unstable
  @ConfigurationScope(Scope.AM)
  @ConfigurationProperty(type="integer")
  public static final String TEZ_COUNTERS_GROUP_NAME_MAX_LENGTH =
      TEZ_PREFIX + "counters.group-name.max-length";
  public static final int TEZ_COUNTERS_GROUP_NAME_MAX_LENGTH_DEFAULT = 256;

  @Unstable
  /**
   * Boolean value. Enable speculative execution of slower tasks. This can help reduce job latency 
   * when some tasks are running slower due bad/slow machines
   */
  @ConfigurationScope(Scope.VERTEX)  // TODO Verify the vertex speculation, TEZ-1788
  @ConfigurationProperty(type="boolean")
  public static final String TEZ_AM_SPECULATION_ENABLED = TEZ_AM_PREFIX + "speculation.enabled";
  public static final boolean TEZ_AM_SPECULATION_ENABLED_DEFAULT = false;
  
  /**
   * Float value. Specifies how many standard deviations away from the mean task execution time 
   * should be considered as an outlier/slow task.
   */
  @Unstable
  @ConfigurationScope(Scope.AM)
  @ConfigurationProperty(type="float")
  public static final String TEZ_AM_LEGACY_SPECULATIVE_SLOWTASK_THRESHOLD =
                                     TEZ_AM_PREFIX + "legacy.speculative.slowtask.threshold";

  /**
   * Int value. Upper limit on the number of threads user to launch containers in the app
   * master. Expert level setting. 
   */
  @ConfigurationScope(Scope.AM)
  @ConfigurationProperty(type="integer")
  public static final String TEZ_AM_CONTAINERLAUNCHER_THREAD_COUNT_LIMIT =
    TEZ_AM_PREFIX + "containerlauncher.thread-count-limit";

  public static final int TEZ_AM_CONTAINERLAUNCHER_THREAD_COUNT_LIMIT_DEFAULT = 
    500;


  /**
   * Int value. Specifies the number of task failures on a node before the node is considered faulty.
   */
  @ConfigurationScope(Scope.AM)
  @ConfigurationProperty(type="integer")
  public static final String TEZ_AM_MAX_TASK_FAILURES_PER_NODE = TEZ_AM_PREFIX
      + "maxtaskfailures.per.node";
  public static final int TEZ_AM_MAX_TASK_FAILURES_PER_NODE_DEFAULT = 10;

  /**
   * Int value. Specifies the number of times the app master can be launched in order to recover 
   * from app master failure. Typically app master failures are non-recoverable. This parameter 
   * is for cases where the app master is not at fault but is lost due to system errors.
   * Expert level setting.
   */
  @ConfigurationScope(Scope.AM)
  @ConfigurationProperty(type="integer")
  public static final String TEZ_AM_MAX_APP_ATTEMPTS = TEZ_AM_PREFIX +
      "max.app.attempts";
  public static final int TEZ_AM_MAX_APP_ATTEMPTS_DEFAULT = 2;

  /**
   * Int value. The maximum number of attempts that can run concurrently for a given vertex.
   * Setting <=0 implies no limit
   */
  @ConfigurationScope(Scope.VERTEX)
  @ConfigurationProperty(type="integer")
  public static final String TEZ_AM_VERTEX_MAX_TASK_CONCURRENCY =
      TEZ_AM_PREFIX + "vertex.max-task-concurrency";
  public static final int TEZ_AM_VERTEX_MAX_TASK_CONCURRENCY_DEFAULT = -1;

  /**
   * Int value. The maximum number of attempts that can fail for a particular task before the task is failed. 
   * This does not count killed attempts. Task failure results in DAG failure.
   */
  @ConfigurationScope(Scope.VERTEX)
  @ConfigurationProperty(type="integer")
  public static final String TEZ_AM_TASK_MAX_FAILED_ATTEMPTS =
      TEZ_AM_PREFIX + "task.max.failed.attempts";
  public static final int TEZ_AM_TASK_MAX_FAILED_ATTEMPTS_DEFAULT = 4;

  /**
   * Boolean value. Enabled blacklisting of nodes of nodes that are considered faulty. These nodes 
   * will not be used to execute tasks.
   */
  @ConfigurationScope(Scope.AM)
  @ConfigurationProperty(type="boolean")
  public static final String TEZ_AM_NODE_BLACKLISTING_ENABLED = TEZ_AM_PREFIX
      + "node-blacklisting.enabled";
  public static final boolean TEZ_AM_NODE_BLACKLISTING_ENABLED_DEFAULT = true;
  
  /**
   * Int value. Specifies the percentage of nodes in the cluster that may be considered faulty.
   * This limits the number of nodes that are blacklisted in an effort to minimize the effects of 
   * temporary surges in failures (e.g. due to network outages). 
   */
  @ConfigurationScope(Scope.AM)
  @ConfigurationProperty(type="integer")
  public static final String TEZ_AM_NODE_BLACKLISTING_IGNORE_THRESHOLD = TEZ_AM_PREFIX
      + "node-blacklisting.ignore-threshold-node-percent";
  public static final int TEZ_AM_NODE_BLACKLISTING_IGNORE_THRESHOLD_DEFAULT = 33;

  /**
   * Boolean value. Enable task rescheduling for node updates.
   * When enabled the task scheduler will reschedule task attempts that
   * are associated with an unhealthy node to avoid potential data transfer
   * errors from downstream tasks.
   */
  @ConfigurationScope(Scope.AM)
  @ConfigurationProperty(type="boolean")
  public static final String TEZ_AM_NODE_UNHEALTHY_RESCHEDULE_TASKS =
      TEZ_AM_PREFIX + "node-unhealthy-reschedule-tasks";
  public static final boolean
    TEZ_AM_NODE_UNHEALTHY_RESCHEDULE_TASKS_DEFAULT = false;

  /** Int value. Number of threads to handle client RPC requests. Expert level setting.*/
  @ConfigurationScope(Scope.AM)
  @ConfigurationProperty(type="integer")
  public static final String TEZ_AM_CLIENT_THREAD_COUNT =
      TEZ_AM_PREFIX + "client.am.thread-count";
  public static final int TEZ_AM_CLIENT_THREAD_COUNT_DEFAULT = 2;
  
  /**
   * String value. Range of ports that the AM can use when binding for client connections. Leave blank
   * to use all possible ports. Expert level setting. It's hadoop standard range configuration.
   * For example 50000-50050,50100-50200
   */
  @ConfigurationScope(Scope.AM)
  @ConfigurationProperty
  public static final String TEZ_AM_CLIENT_AM_PORT_RANGE =
      TEZ_AM_PREFIX + "client.am.port-range";

  /**
   * String value. Range of ports that the AM can use when binding for task connections. Leave blank
   * to use all possible ports. Expert level setting. It's hadoop standard range configuration.
   * For example 50000-50050,50100-50200
   */
  @ConfigurationScope(Scope.AM)
  public static final String TEZ_AM_TASK_AM_PORT_RANGE =
      TEZ_AM_PREFIX + "task.am.port-range";

  /**
   * String value. The class to be used for DAG Scheduling. Expert level setting.
   */
  @ConfigurationScope(Scope.DAG)
  @ConfigurationProperty
  public static final String TEZ_AM_DAG_SCHEDULER_CLASS = TEZ_AM_PREFIX + "dag.scheduler.class";
  public static final String TEZ_AM_DAG_SCHEDULER_CLASS_DEFAULT =
      "org.apache.tez.dag.app.dag.impl.DAGSchedulerNaturalOrder";

  /** Int value. The amount of memory in MB to be used by the AppMaster */
  @ConfigurationScope(Scope.AM)
  @ConfigurationProperty(type="integer")
  public static final String TEZ_AM_RESOURCE_MEMORY_MB = TEZ_AM_PREFIX
      + "resource.memory.mb";
  public static final int TEZ_AM_RESOURCE_MEMORY_MB_DEFAULT = 1024;

  /** Int value. The number of virtual cores to be used by the app master */
  @ConfigurationScope(Scope.AM)
  @ConfigurationProperty(type="integer")
  public static final String TEZ_AM_RESOURCE_CPU_VCORES = TEZ_AM_PREFIX
      + "resource.cpu.vcores";
  public static final int TEZ_AM_RESOURCE_CPU_VCORES_DEFAULT = 1;
  
  /** Int value. The amount of memory in MB to be used by tasks. This applies to all tasks across
   * all vertices. Setting it to the same value for all tasks is helpful for container reuse and 
   * thus good for performance typically. */
  @ConfigurationScope(Scope.DAG)  // TODO vertex level
  @ConfigurationProperty(type="integer")
  public static final String TEZ_TASK_RESOURCE_MEMORY_MB = TEZ_TASK_PREFIX
      + "resource.memory.mb";
  public static final int TEZ_TASK_RESOURCE_MEMORY_MB_DEFAULT = 1024;

  /**
   * Int value. The number of virtual cores to be used by tasks.
   */
  @ConfigurationScope(Scope.DAG)  // TODO vertex level
  @ConfigurationProperty(type="integer")
  public static final String TEZ_TASK_RESOURCE_CPU_VCORES = TEZ_TASK_PREFIX
      + "resource.cpu.vcores";
  public static final int TEZ_TASK_RESOURCE_CPU_VCORES_DEFAULT = 1; 

  /**
   * Int value. The maximum heartbeat interval between the AM and RM in milliseconds
   * Increasing this reduces the communication between the AM and the RM and can
   * help in scaling up. Expert level setting.
   */
  @ConfigurationScope(Scope.AM)
  @ConfigurationProperty(type="integer")
  public static final String TEZ_AM_RM_HEARTBEAT_INTERVAL_MS_MAX = TEZ_AM_PREFIX
      + "am-rm.heartbeat.interval-ms.max";
  public static final int TEZ_AM_RM_HEARTBEAT_INTERVAL_MS_MAX_DEFAULT = 1000;

  /**
   * Int value. The maximum amount of time, in milliseconds, to wait before a task asks an
   * AM for another task. Increasing this can help improve app master scalability for a large 
   * number of concurrent tasks. Expert level setting.
   */
  @ConfigurationScope(Scope.AM)
  @ConfigurationProperty(type="integer")
  public static final String TEZ_TASK_GET_TASK_SLEEP_INTERVAL_MS_MAX = TEZ_TASK_PREFIX
      + "get-task.sleep.interval-ms.max";
  public static final int TEZ_TASK_GET_TASK_SLEEP_INTERVAL_MS_MAX_DEFAULT = 200;

  /**
   * Int value. The maximum heartbeat interval, in milliseconds, between the app master and tasks. 
   * Increasing this can help improve app master scalability for a large number of concurrent tasks.
   * Expert level setting.
   */
  @ConfigurationScope(Scope.AM)
  @ConfigurationProperty(type="integer")
  public static final String TEZ_TASK_AM_HEARTBEAT_INTERVAL_MS = TEZ_TASK_PREFIX
      + "am.heartbeat.interval-ms.max";
  public static final int TEZ_TASK_AM_HEARTBEAT_INTERVAL_MS_DEFAULT = 100;

  /**
   * Int value. Interval, in milliseconds, after which counters are sent to AM in heartbeat from 
   * tasks. This reduces the amount of network traffice between AM and tasks to send high-volume 
   * counters. Improves AM scalability. Expert level setting.
   */
  @ConfigurationScope(Scope.AM)
  @ConfigurationProperty(type="integer")
  public static final String TEZ_TASK_AM_HEARTBEAT_COUNTER_INTERVAL_MS = TEZ_TASK_PREFIX
      + "am.heartbeat.counter.interval-ms.max";
  public static final int TEZ_TASK_AM_HEARTBEAT_COUNTER_INTERVAL_MS_DEFAULT =
      4000;

  /**
   * Int value. Maximum number of of events to fetch from the AM by the tasks in a single heartbeat.
   * Expert level setting. Expert level setting.
   */
  @ConfigurationScope(Scope.AM)
  @ConfigurationProperty(type="integer")
  public static final String TEZ_TASK_MAX_EVENTS_PER_HEARTBEAT = TEZ_TASK_PREFIX
      + "max-events-per-heartbeat";
  public static final int TEZ_TASK_MAX_EVENTS_PER_HEARTBEAT_DEFAULT = 500;
  
  /**
   * Int value. Maximum number of pending task events before a task will stop
   * asking for more events in the task heartbeat.
   * Expert level setting.
   */
  @ConfigurationScope(Scope.AM)
  @ConfigurationProperty(type="integer")
  public static final String TEZ_TASK_MAX_EVENT_BACKLOG = TEZ_TASK_PREFIX +
      "max-event-backlog";
  public static final int TEZ_TASK_MAX_EVENT_BACKLOG_DEFAULT = 10000;

  /**
   * Boolean value. Backwards compatibility setting for initializing IO processor before
   * inputs and outputs.
   * Expert level setting.
   */
  @ConfigurationScope(Scope.AM)
  @ConfigurationProperty(type="boolean")
  public static final String TEZ_TASK_INITIALIZE_PROCESSOR_FIRST = TEZ_TASK_PREFIX +
      "initialize-processor-first";
  public static final boolean TEZ_TASK_INITIALIZE_PROCESSOR_FIRST_DEFAULT = false;

  /**
   * Boolean value. Backwards compatibility setting for initializing inputs and outputs
   * serially instead of the parallel default.
   * Expert level setting.
   */
  @ConfigurationScope(Scope.AM)
  @ConfigurationProperty(type="boolean")
  public static final String TEZ_TASK_INITIALIZE_PROCESSOR_IO_SERIALLY = TEZ_TASK_PREFIX +
      "initialize-processor-io-serially";
  public static final boolean TEZ_TASK_INITIALIZE_PROCESSOR_IO_SERIALLY_DEFAULT = false;

  /**
   * Long value. Interval, in milliseconds, within which any of the tasks Input/Processor/Output 
   * components need to make successive progress notifications. If the progress is not notified 
   * for this interval then the task will be considered hung and terminated.
   * The value for this config should be larger than {@link TezConfiguration#TASK_HEARTBEAT_TIMEOUT_MS} 
   * and larger than 2 times the value of {@link TezConfiguration#TEZ_TASK_AM_HEARTBEAT_INTERVAL_MS}.
   * A config value <=0 disables this.
   */
  @ConfigurationScope(Scope.VERTEX)
  @ConfigurationProperty
  public static final String TEZ_TASK_PROGRESS_STUCK_INTERVAL_MS = TEZ_TASK_PREFIX + 
    "progress.stuck.interval-ms";
  public static final long TEZ_TASK_PROGRESS_STUCK_INTERVAL_MS_DEFAULT = -1;

  /**
   * Whether to generate counters per IO or not. Enabling this will rename
   * CounterGroups / CounterNames to making them unique per Vertex +
   * Src|Destination
   */
  @Unstable
  @Private
  @ConfigurationScope(Scope.AM)
  @ConfigurationProperty(type="boolean")
  public static final String TEZ_TASK_GENERATE_COUNTERS_PER_IO = TEZ_TASK_PREFIX
      + "generate.counters.per.io";
  @Private
  public static final boolean TEZ_TASK_GENERATE_COUNTERS_PER_IO_DEFAULT = false;

  /**
   * Int value. Time interval, in milliseconds, within which a task must heartbeat to the app master
   * before its considered lost.
   * Expert level setting.
   */
  @ConfigurationScope(Scope.AM)
  @ConfigurationProperty(type="integer")
  public static final String TASK_HEARTBEAT_TIMEOUT_MS = TEZ_TASK_PREFIX + "timeout-ms";

  public static final int TASK_HEARTBEAT_TIMEOUT_MS_DEFAULT = 5 * 60 * 1000;

  /**
   * Int value. Time interval, in milliseconds, between checks for lost tasks.
   * Expert level setting.
   */
  @ConfigurationScope(Scope.AM)
  @ConfigurationProperty(type="integer")
  public static final String TASK_HEARTBEAT_TIMEOUT_CHECK_MS = TEZ_TASK_PREFIX + "heartbeat.timeout.check-ms";

  public static final int TASK_HEARTBEAT_TIMEOUT_CHECK_MS_DEFAULT = 30 * 1000;

  /**
   * Whether to scale down memory requested by each component if the total
   * exceeds the available JVM memory
   */
  @Private
  @Unstable
  @ConfigurationScope(Scope.VERTEX)
  @ConfigurationProperty(type="boolean")
  public static final String TEZ_TASK_SCALE_MEMORY_ENABLED = TEZ_TASK_PREFIX
      + "scale.memory.enabled";
  @Private
  public static final boolean TEZ_TASK_SCALE_MEMORY_ENABLED_DEFAULT = true;

  /**
   * The allocator to use for initial memory allocation
   */
  @Private
  @Unstable
  @ConfigurationScope(Scope.VERTEX)
  @ConfigurationProperty
  public static final String TEZ_TASK_SCALE_MEMORY_ALLOCATOR_CLASS = TEZ_TASK_PREFIX
      + "scale.memory.allocator.class";
  @Private
  public static final String TEZ_TASK_SCALE_MEMORY_ALLOCATOR_CLASS_DEFAULT =
      "org.apache.tez.runtime.library.resources.WeightedScalingMemoryDistributor";

  /**
   * The fraction of the JVM memory which will not be considered for allocation.
   * No defaults, since there are pre-existing defaults based on different scenarios.
   */
  @Private
  @Unstable
  @ConfigurationScope(Scope.VERTEX)
  @ConfigurationProperty(type="double")
  public static final String TEZ_TASK_SCALE_MEMORY_RESERVE_FRACTION = TEZ_TASK_PREFIX
      + "scale.memory.reserve-fraction";
  @Private
  public static final double TEZ_TASK_SCALE_MEMORY_RESERVE_FRACTION_DEFAULT = 0.3d;

  /**
   * Fraction of available memory to reserve per input/output. This amount is
   * removed from the total available pool before allocation and is for factoring in overheads.
   */
  @Private
  @Unstable
  @ConfigurationScope(Scope.VERTEX)
  @ConfigurationProperty(type="float")
  public static final String TEZ_TASK_SCALE_MEMORY_ADDITIONAL_RESERVATION_FRACTION_PER_IO =
      TEZ_TASK_PREFIX + "scale.memory.additional-reservation.fraction.per-io";

  @Private
  @Unstable
  /**
   * Max cumulative total reservation for additional IOs.
   */
  @ConfigurationScope(Scope.VERTEX)
  @ConfigurationProperty(type="float")
  public static final String TEZ_TASK_SCALE_MEMORY_ADDITIONAL_RESERVATION_FRACTION_MAX =
      TEZ_TASK_PREFIX + "scale.memory.additional-reservation.fraction.max";
  /*
   * Weighted ratios for individual component types in the RuntimeLibrary.
   * e.g. PARTITIONED_UNSORTED_OUTPUT:0,UNSORTED_INPUT:1,UNSORTED_OUTPUT:0,SORTED_OUTPUT:2,
   * SORTED_MERGED_INPUT:3,PROCESSOR:1,OTHER:1
   */
  @Private
  @Unstable
  @ConfigurationScope(Scope.VERTEX)
  @ConfigurationProperty
  public static final String TEZ_TASK_SCALE_MEMORY_WEIGHTED_RATIOS =
      TEZ_TASK_PREFIX + "scale.memory.ratios";

  /**
   * Concurrent input/output memory allocation control. When enabled memory
   * distributions assume that inputs and outputs will use their memory
   * simultaneously. When disabled the distributions assume that outputs are not
   * initialized until inputs release memory buffers, allowing inputs to
   * leverage memory normally set aside for outputs and vice-versa.
   * NOTE: This property currently is not supported by the ScalingAllocator
   *       memory distributor.
   */
  @Private
  @Unstable
  @ConfigurationScope(Scope.VERTEX)
  public static final String TEZ_TASK_SCALE_MEMORY_INPUT_OUTPUT_CONCURRENT =
      TEZ_TASK_PREFIX + "scale.memory.input-output-concurrent";
  public static final boolean TEZ_TASK_SCALE_MEMORY_INPUT_OUTPUT_CONCURRENT_DEFAULT = true;

  /**
   * Controls distributing output memory to inputs when non-concurrent I/O
   * memory allocation is being used.  When enabled inputs will receive the
   * same memory allocation as if concurrent I/O memory allocation were used.
   * NOTE: This property currently is not supported by the ScalingAllocator
   *       memory distributor.
   */
  @Private
  @Unstable
  @ConfigurationScope(Scope.VERTEX)
  public static final String TEZ_TASK_SCALE_MEMORY_NON_CONCURRENT_INPUTS_ENABLED =
      TEZ_TASK_PREFIX + "scale.memory.non-concurrent-inputs.enabled";
  public static final boolean TEZ_TASK_SCALE_MEMORY_NON_CONCURRENT_INPUTS_ENABLED_DEFAULT = false;

  @Private
  @Unstable
  /**
   * Defines the ProcessTree implementation which will be used to collect resource utilization.
   */
  @ConfigurationScope(Scope.AM)
  @ConfigurationProperty
  public static final String TEZ_TASK_RESOURCE_CALCULATOR_PROCESS_TREE_CLASS =
      TEZ_TASK_PREFIX + "resource.calculator.process-tree.class";


  /**
   * Boolean value. Configuration to specify whether container should be reused across tasks.
   * This improves performance by not incurring recurring launch overheads.
   */
  @ConfigurationScope(Scope.AM)
  @ConfigurationProperty(type="boolean")
  public static final String TEZ_AM_CONTAINER_REUSE_ENABLED = TEZ_AM_PREFIX
      + "container.reuse.enabled";
  public static final boolean TEZ_AM_CONTAINER_REUSE_ENABLED_DEFAULT = true;

  /**
   * Boolean value. Whether to reuse containers for rack local tasks. Active only if reuse is
   * enabled.
   */
  @ConfigurationScope(Scope.AM)
  @ConfigurationProperty(type="boolean")
  public static final String TEZ_AM_CONTAINER_REUSE_RACK_FALLBACK_ENABLED =
      TEZ_AM_PREFIX + "container.reuse.rack-fallback.enabled";
  public static final boolean
      TEZ_AM_CONTAINER_REUSE_RACK_FALLBACK_ENABLED_DEFAULT = true;

  /**
   * Boolean value. Whether to reuse containers for non-local tasks. Active only if reuse is
   * enabled. Turning this on can severely affect locality and can be bad for jobs with high data 
   * volume being read from the primary data sources.
   */
  @ConfigurationScope(Scope.AM)
  @ConfigurationProperty(type="boolean")
  public static final String TEZ_AM_CONTAINER_REUSE_NON_LOCAL_FALLBACK_ENABLED =
      TEZ_AM_PREFIX + "container.reuse.non-local-fallback.enabled";
  public static final boolean
      TEZ_AM_CONTAINER_REUSE_NON_LOCAL_FALLBACK_ENABLED_DEFAULT = false;

  /**
   * Int value. The amount of time to wait before assigning a container to the next level
   * of locality. NODE -> RACK -> NON_LOCAL. Delay scheduling parameter. Expert level setting.
   */
  @ConfigurationScope(Scope.AM)
  @ConfigurationProperty(type="long")
  public static final String
      TEZ_AM_CONTAINER_REUSE_LOCALITY_DELAY_ALLOCATION_MILLIS =
      TEZ_AM_PREFIX + "container.reuse.locality.delay-allocation-millis";
  public static final long
    TEZ_AM_CONTAINER_REUSE_LOCALITY_DELAY_ALLOCATION_MILLIS_DEFAULT = 250l;

  /**
   * Int value. The minimum amount of time to hold on to a container that is idle. Only active when 
   * reuse is enabled. Set to -1 to never release idle containers (not recommended). 
   */
  @ConfigurationScope(Scope.AM)
  @ConfigurationProperty(type="integer")
  public static final String TEZ_AM_CONTAINER_IDLE_RELEASE_TIMEOUT_MIN_MILLIS =
    TEZ_AM_PREFIX + "container.idle.release-timeout-min.millis";
  public static final long
    TEZ_AM_CONTAINER_IDLE_RELEASE_TIMEOUT_MIN_MILLIS_DEFAULT = 5000l;  

  /**
   * Int value. The maximum amount of time to hold on to a container if no task can be
   * assigned to it immediately. Only active when reuse is enabled. The value
   * must be +ve and >=
   * TezConfiguration#TEZ_AM_CONTAINER_IDLE_RELEASE_TIMEOUT_MIN_MILLIS.
   * Containers will have an expire time set to a random value between
   * TezConfiguration#TEZ_AM_CONTAINER_IDLE_RELEASE_TIMEOUT_MIN_MILLIS &&
   * TezConfiguration#TEZ_AM_CONTAINER_IDLE_RELEASE_TIMEOUT_MAX_MILLIS. This 
   * creates a graceful reduction in the amount of idle resources held
   */
  @ConfigurationScope(Scope.AM)
  @ConfigurationProperty(type="long")
  public static final String TEZ_AM_CONTAINER_IDLE_RELEASE_TIMEOUT_MAX_MILLIS =
      TEZ_AM_PREFIX + "container.idle.release-timeout-max.millis";
  public static final long
    TEZ_AM_CONTAINER_IDLE_RELEASE_TIMEOUT_MAX_MILLIS_DEFAULT = 10000l;
  
  /**
   * Int value. The minimum number of containers that will be held in session mode. Not active in 
   * non-session mode. Enables an idle session (not running any DAG) to hold on to a minimum number
   * of containers to provide fast response times for the next DAG.
   */
  @ConfigurationScope(Scope.AM)
  @ConfigurationProperty(type="integer")
  public static final String TEZ_AM_SESSION_MIN_HELD_CONTAINERS =
      TEZ_AM_PREFIX + "session.min.held-containers";
  public static final int TEZ_AM_SESSION_MIN_HELD_CONTAINERS_DEFAULT = 0;

  /**
   * Boolean value. Allow/disable logging for all dags in a session   
   */
  @Private
  @ConfigurationScope(Scope.AM)
  public static final String TEZ_AM_HISTORY_LOGGING_ENABLED =
      TEZ_AM_PREFIX + "history.logging.enabled";
  public static final boolean TEZ_AM_HISTORY_LOGGING_ENABLED_DEFAULT = true;

  /**
   * Int value. Specifies the percentage of tasks eligible to be preempted that
   * will actually be preempted in a given round of Tez internal preemption.
   * This slows down preemption and gives more time for free resources to be
   * allocated by the cluster (if any) and gives more time for preemptable tasks
   * to finish. Valid values are 0-100. Higher values will preempt quickly at
   * the cost of losing work. Setting to 0 turns off preemption. Expert level
   * setting.
   */
  @ConfigurationScope(Scope.AM)
  @ConfigurationProperty(type="integer")
  public static final String TEZ_AM_PREEMPTION_PERCENTAGE =
      TEZ_AM_PREFIX + "preemption.percentage";
  public static final int TEZ_AM_PREEMPTION_PERCENTAGE_DEFAULT = 10;

  /**
   * Float value. Specifies the allowable percentage in the range 0.0-100.0f of task
   * failures per vertex that will allow the vertex to succeed with failures.
   */
  @ConfigurationScope(Scope.VERTEX)
  public static final String TEZ_VERTEX_FAILURES_MAXPERCENT =
          "tez.vertex.failures.maxpercent";
  public static final float TEZ_VERTEX_FAILURES_MAXPERCENT_DEFAULT = 0.0f;
  /**
   * Int value. The number of RM heartbeats to wait after preempting running tasks before preempting
   * more running tasks. After preempting a task, we need to wait at least 1 heartbeat so that the 
   * RM can act on the released resources and assign new ones to us. Expert level setting.
   */
  @ConfigurationScope(Scope.AM)
  @ConfigurationProperty(type="integer")
  public static final String TEZ_AM_PREEMPTION_HEARTBEATS_BETWEEN_PREEMPTIONS =
      TEZ_AM_PREFIX + "preemption.heartbeats-between-preemptions";
  public static final int TEZ_AM_PREEMPTION_HEARTBEATS_BETWEEN_PREEMPTIONS_DEFAULT = 3;

  /**
   * Int value. Time (in millisecs) that an unsatisfied request will wait before preempting other
   * resources. In rare cases, the cluster says there are enough free resources but does not end 
   * up getting enough on a node to actually assign it to the job. This configuration tries to put 
   * a deadline on such wait to prevent indefinite job hangs.
   */
  @ConfigurationScope(Scope.AM)
  @ConfigurationProperty(type="integer")
  public static final String TEZ_AM_PREEMPTION_MAX_WAIT_TIME_MS =
      TEZ_AM_PREFIX + "preemption.max.wait-time-ms";
  public static final int TEZ_AM_PREEMPTION_MAX_WAIT_TIME_MS_DEFAULT = 60*1000; // 60s

  /**
   * String value to a file path.
   * The location of the Tez libraries which will be localized for DAGs.
   * This follows the following semantics
   * <ol>
   * <li> To use .tar.gz or .tgz files (generated by the tez or hadoop builds), the full path to this
   * file (including filename) should be specified. The internal structure of the uncompressed tgz
   * will be defined by 'tez.lib.uris.classpath'</li>
   *
   * <li> If a single file is specified without the above mentioned extensions - it will be treated as
   * a regular file. This means it will not be uncompressed during runtime. </li>
   *
   * <li> If multiple entries exist
   * <ul>
   * <li> Regular Files: will be treated as regular files (not uncompressed during runtime) </li>
   * <li> Archive Files: will be treated as archives and will be uncompressed during runtime </li>
   * <li> Directories: all files under the directory (non-recursive) will be made available (but not
   * uncompressed during runtime). </li>
   * </ul>
   * </ol>
   */
  @ConfigurationScope(Scope.AM)
  @ConfigurationProperty
  public static final String TEZ_LIB_URIS = TEZ_PREFIX + "lib.uris";

  /**
   *
   * Specify additional user classpath information to be used for Tez AM and all containers.
   * This will be appended to the classpath after PWD
   * 
   * 'tez.lib.uris.classpath' defines the relative classpath into the archives
   * that are set in 'tez.lib.uris'
   *
   */
  @ConfigurationScope(Scope.AM)
  @ConfigurationProperty
  public static final String TEZ_LIB_URIS_CLASSPATH = TEZ_PREFIX + "lib.uris.classpath";

  /**
   * Auxiliary resources to be localized for the Tez AM and all its containers.
   *
   * Value is comma-separated list of fully-resolved directories or file paths. All resources
   * are made available into the working directory of the AM and/or containers i.e. $CWD.
   *
   * If directories are specified, they are not traversed recursively. Only files directly under the
   * specified directory are localized.
   *
   * All duplicate resources are ignored.
   *
   */
  @ConfigurationScope(Scope.AM)
  @ConfigurationProperty
  public static final String TEZ_AUX_URIS = TEZ_PREFIX + "aux.uris";

  /**
   * Boolean value. Allows to ignore 'tez.lib.uris'. Useful during development as well as 
   * raw Tez application where classpath is propagated with application
   * via {@link LocalResource}s. This is mainly useful for developer/debugger scenarios.
   */
  @Unstable
  @ConfigurationScope(Scope.AM)
  @ConfigurationProperty(type="boolean")
  public static final String TEZ_IGNORE_LIB_URIS = TEZ_PREFIX + "ignore.lib.uris";

  /**
   * Boolean value.
   * Specify whether hadoop libraries required to run Tez should be the ones deployed on the cluster.
   * This is disabled by default - with the expectation being that tez.lib.uris has a complete
   * tez-deployment which contains the hadoop libraries.
   */
  @ConfigurationScope(Scope.AM)
  @ConfigurationProperty(type="boolean")
  public static final String TEZ_USE_CLUSTER_HADOOP_LIBS = TEZ_PREFIX + "use.cluster.hadoop-libs";
  public static final boolean TEZ_USE_CLUSTER_HADOOP_LIBS_DEFAULT = false;

  /**
   * Boolean value.
   * Specify whether the user classpath takes precedence over the Tez framework
   * classpath.
   */
  @ConfigurationScope(Scope.CLIENT)
  @ConfigurationProperty(type="boolean")
  public static final String TEZ_USER_CLASSPATH_FIRST = TEZ_PREFIX + "user.classpath.first";
  public static final boolean TEZ_USER_CLASSPATH_FIRST_DEFAULT = true;

  /**
   * String value.
   *
   * Specify additional classpath information to be used for Tez AM and all containers.
   * If {@link #TEZ_USER_CLASSPATH_FIRST} is true then this will be added to the classpath
   * before all framework specific components have been specified, otherwise this will
   * be added after the framework specific components.
   */
  @ConfigurationScope(Scope.AM)
  @ConfigurationProperty
  public static final String TEZ_CLUSTER_ADDITIONAL_CLASSPATH_PREFIX =
      TEZ_PREFIX + "cluster.additional.classpath.prefix";

  /**
   * Boolean value.
   * If this value is true then tez explicitly adds hadoop conf directory into classpath for AM and
   * task containers. Default is false.
   */
  @Private
  @Unstable
  @ConfigurationScope(Scope.CLIENT)
  @ConfigurationProperty(type="boolean")
  public static final String TEZ_CLASSPATH_ADD_HADOOP_CONF = TEZ_PREFIX +
      "classpath.add-hadoop-conf";
  public static final boolean TEZ_CLASSPATH_ADD_HADOOP_CONF_DEFAULT = false;

  /**
   * Session-related properties
   */
  @Private
  @ConfigurationProperty
  public static final String TEZ_SESSION_PREFIX =
      TEZ_PREFIX + "session.";

  /**
   * Int value. Time (in seconds) to wait for AM to come up when trying to submit a DAG
   * from the client. Only relevant in session mode. If the cluster is busy and cannot launch the 
   * AM then this timeout may be hit. In those case, using non-session mode is recommended if 
   * applicable. Otherwise increase the timeout (set to -1 for infinity. Not recommended)
   */
  @ConfigurationScope(Scope.AM)
  @ConfigurationProperty(type="integer")
  public static final String TEZ_SESSION_CLIENT_TIMEOUT_SECS =
      TEZ_SESSION_PREFIX + "client.timeout.secs";
  public static final int TEZ_SESSION_CLIENT_TIMEOUT_SECS_DEFAULT =
      120;

  /**
   * Int value. Time (in seconds) for which the Tez AM should wait for a DAG to be submitted before
   * shutting down. Only relevant in session mode. Any negative value will disable this check and
   * allow the AM to hang around forever in idle mode.
   */
  @ConfigurationScope(Scope.AM)
  @ConfigurationProperty(type="integer")
  public static final String TEZ_SESSION_AM_DAG_SUBMIT_TIMEOUT_SECS =
      TEZ_SESSION_PREFIX + "am.dag.submit.timeout.secs";
  public static final int TEZ_SESSION_AM_DAG_SUBMIT_TIMEOUT_SECS_DEFAULT =
      300;

  /**
   * String value. The queue name for all jobs being submitted from a given client.
   */
  @ConfigurationScope(Scope.AM)
  @ConfigurationProperty
  public static final String TEZ_QUEUE_NAME = TEZ_PREFIX + "queue.name";

  /**
   * String value. Tags for the job that will be passed to YARN at submission
   * time. Queries to YARN for applications can filter on these tags.
   */
  @ConfigurationScope(Scope.AM)
  @ConfigurationProperty
  public static final String TEZ_APPLICATION_TAGS = TEZ_PREFIX + "application.tags";

  /**
   * String value. The job priority of submitted application.
   */
  @ConfigurationScope(Scope.AM)
  public static final String TEZ_AM_APPLICATION_PRIORITY = TEZ_PREFIX + "am.application.priority";

  @Unstable
  /**
   * Boolean value. Generate debug artifacts like DAG plan in text format.
   */
  @ConfigurationScope(Scope.DAG)
  @ConfigurationProperty(type="boolean")
  public static final String TEZ_GENERATE_DEBUG_ARTIFACTS =
      TEZ_PREFIX + "generate.debug.artifacts";
  public static final boolean TEZ_GENERATE_DEBUG_ARTIFACTS_DEFAULT = false;

  /**
   * Set of tasks for which specific launch command options need to be added.
   * Format: "vertexName[csv of task ids];vertexName[csv of task ids].."
   * Valid e.g:
   * v[0,1,2]  - Additional launch-cmd options for tasks 0,1,2 of vertex v
   * v[1,2,3];v2[5,6,7] - Additional launch-cmd options specified for tasks of vertices v and v2.
   * v[1:5,20,30];v2[2:5,60,7] - Additional launch-cmd options for 1,2,3,4,5,20,30 of vertex v; 2,
   * 3,4,5,60,7 of vertex v2
   * Partial ranges like :5, 1: are not supported.
   * v[] - Additional launch-cmd options for all tasks in vertex v
   */
  @Unstable
  @ConfigurationScope(Scope.AM)
  @ConfigurationProperty
  public static final String TEZ_TASK_SPECIFIC_LAUNCH_CMD_OPTS_LIST = TEZ_PREFIX + "task-specific" +
      ".launch.cmd-opts.list";

  /**
   * Additional launch command options to be added for specific tasks.
   * __VERTEX_NAME__ and __TASK_INDEX__ can be specified, which would be replaced at
   * runtime by vertex name and task index.
   * e.g tez.task-specific.launch.cmd-opts=
   * "-agentpath:libpagent.so,dir=/tmp/__VERTEX_NAME__/__TASK_INDEX__"
   */
  @Unstable
  @ConfigurationScope(Scope.AM)
  @ConfigurationProperty
  public static final String TEZ_TASK_SPECIFIC_LAUNCH_CMD_OPTS = TEZ_PREFIX + "task-specific" +
      ".launch.cmd-opts";

  /**
   * Task specific log level.
   *
   * Simple configuration: Set the log level for all loggers.
   *   e.g. INFO
   *   This sets the log level to INFO for all loggers.
   *
   * Advanced configuration: Set the log level for all classes, along with a different level for some.
   *   e.g. DEBUG;org.apache.hadoop.ipc=INFO;org.apache.hadoop.security=INFO
   *   This sets the log level for all loggers to DEBUG, expect for the
   *   org.apache.hadoop.ipc and org.apache.hadoop.security, which are set to INFO
   *
   * Note: The global log level must always be the first parameter.
   *   DEBUG;org.apache.hadoop.ipc=INFO;org.apache.hadoop.security=INFO is valid
   *   org.apache.hadoop.ipc=INFO;org.apache.hadoop.security=INFO is not valid
   * */
  @Unstable
  @ConfigurationScope(Scope.AM)
  @ConfigurationProperty
  public static final String TEZ_TASK_SPECIFIC_LOG_LEVEL = TEZ_PREFIX + "task-specific" + ".log.level";

  /**
   * String value that is a class name.
   * Specify the class to use for logging history data.
   * To disable, set this to "org.apache.tez.dag.history.logging.impl.DevNullHistoryLoggingService"
   */
  @ConfigurationScope(Scope.AM)
  @ConfigurationProperty
  public static final String TEZ_HISTORY_LOGGING_SERVICE_CLASS =
      TEZ_PREFIX + "history.logging.service.class";

  public static final String TEZ_HISTORY_LOGGING_SERVICE_CLASS_DEFAULT =
      "org.apache.tez.dag.history.logging.impl.SimpleHistoryLoggingService";

  /**
   * Enum value. Config to limit the type of events published to the history logging service.
   * The valid log levels are defined in the enum {@link HistoryLogLevel}. The default value is
   * defined in {@link HistoryLogLevel#DEFAULT}.
   */
  @ConfigurationScope(Scope.DAG)
  @ConfigurationProperty
  public static final String TEZ_HISTORY_LOGGING_LOGLEVEL =
      TEZ_PREFIX + "history.logging.log.level";

  /**
   * List of comma separated enum values. Specifies the list of task attempt termination causes,
   * which have to be suppressed from being logged to ATS. The valid filters are defined in the
   * enum TaskAttemptTerminationCause. The filters are applied only if tez.history.logging.log.level
   * is set to TASK_ATTEMPT.
   */
  @ConfigurationScope(Scope.DAG)
  @ConfigurationProperty
  public static final String TEZ_HISTORY_LOGGING_TASKATTEMPT_FILTERS =
      TEZ_PREFIX + "history.logging.taskattempt-filters";

  /**
   * Comma separated list of Integers. These are the values that were set for the config value
   * for {@value #TEZ_HISTORY_LOGGING_TIMELINE_NUM_DAGS_PER_GROUP}. The older values are required so
   * that the groupIds generated previously will continue to be generated by the plugin. If an older
   * value is not present then the UI may not show information for DAGs which were created
   * with a different grouping value.
   *
   * Note: Do not add too many values here as it will affect the performance of Yarn Timeline
   * Server/Tez UI due to the need to scan for more log files.
   */
  @Private
  @Unstable
  @ConfigurationScope(Scope.AM)
  @ConfigurationProperty
  public static final String TEZ_HISTORY_LOGGING_TIMELINE_CACHE_PLUGIN_OLD_NUM_DAGS_PER_GROUP =
      TEZ_PREFIX + "history.logging.timeline-cache-plugin.old-num-dags-per-group";

  /**
   * Integer value. Number of DAGs to be grouped together. This is used by the history logging
   * service to generate groupIds such that numDagsPerGroup will have same groupId in a given
   * session. If the value is set to 1 then we disable grouping. This config is used to control the
   * number of DAGs written into one log file, and hence controls number of files created in
   * the Filesystem used by YARN Timeline.
   */
  @Private
  @Unstable
  @ConfigurationScope(Scope.AM)
  @ConfigurationProperty(type="integer")
  public static final String TEZ_HISTORY_LOGGING_TIMELINE_NUM_DAGS_PER_GROUP =
      TEZ_PREFIX + "history.logging.timeline.num-dags-per-group";
  public static final int TEZ_HISTORY_LOGGING_TIMELINE_NUM_DAGS_PER_GROUP_DEFAULT = 1;

  /**
   * String value. The directory into which history data will be written. This defaults to the 
   * container logging directory. This is relevant only when SimpleHistoryLoggingService is being
   * used for {@link TezConfiguration#TEZ_HISTORY_LOGGING_SERVICE_CLASS}
   */
  @ConfigurationScope(Scope.AM)
  @ConfigurationProperty
  public static final String TEZ_SIMPLE_HISTORY_LOGGING_DIR =
      TEZ_PREFIX + "simple.history.logging.dir";

  /**
   * Int value. Maximum errors allowed while logging history data. After crossing this limit history
   * logging gets disabled. The job continues to run after this.
   */
  @ConfigurationScope(Scope.AM)
  @ConfigurationProperty(type="integer")
  public static final String TEZ_SIMPLE_HISTORY_LOGGING_MAX_ERRORS =
      TEZ_PREFIX + "simple.history.max.errors";
  public static final int TEZ_SIMPLE_HISTORY_LOGGING_MAX_ERRORS_DEFAULT = 10;

  /**
   * Int value. Time, in milliseconds, to wait while flushing YARN ATS data during shutdown.
   * Expert level setting.
   */
  @ConfigurationScope(Scope.AM)
  @ConfigurationProperty(type="long")
  public static final String YARN_ATS_EVENT_FLUSH_TIMEOUT_MILLIS =
      TEZ_PREFIX + "yarn.ats.event.flush.timeout.millis";
  public static final long YARN_ATS_EVENT_FLUSH_TIMEOUT_MILLIS_DEFAULT =
      -1;

  /**
   * Int value. Max no. of events to send in a single batch to ATS.
   * Expert level setting.
   */
  @ConfigurationScope(Scope.AM)
  @ConfigurationProperty(type="integer")
  public static final String YARN_ATS_MAX_EVENTS_PER_BATCH =
      TEZ_PREFIX + "yarn.ats.max.events.per.batch";
  public static final int YARN_ATS_MAX_EVENTS_PER_BATCH_DEFAULT = 5;

  /**
   * Boolean value. Default true.
   * Whether to fix the history url if it has not been configured correctly i.e. it does not have a
   * scheme in the value. By default, the url will be prepended with a scheme (http) if there is
   * none present.
   */
  @Private
  @ConfigurationScope(Scope.AM)
  public static final String TEZ_AM_UI_HISTORY_URL_SCHEME_CHECK_ENABLED =
      TEZ_PREFIX + "am.ui.history.url.scheme.check.enabled";
  public static final boolean TEZ_AM_UI_HISTORY_URL_SCHEME_CHECK_ENABLED_DEFAULT = true;


  /**
   * Int value. Time, in milliseconds, to wait for an event before sending a batch to ATS.
   * Expert level setting.
   */
  @ConfigurationScope(Scope.AM)
  @ConfigurationProperty(type="integer")
  public static final String YARN_ATS_MAX_POLLING_TIME_PER_EVENT = TEZ_PREFIX
      + "yarn.ats.max.polling.time.per.event.millis";
  public static final int YARN_ATS_MAX_POLLING_TIME_PER_EVENT_DEFAULT = 10;

  @ConfigurationScope(Scope.AM)
  @ConfigurationProperty(type="boolean")
  public static final String YARN_ATS_ACL_DOMAINS_AUTO_CREATE = TEZ_PREFIX
      + "yarn.ats.acl.domains.auto-create";
  public static final boolean YARN_ATS_ACL_DOMAINS_AUTO_CREATE_DEFAULT = true;

  @ConfigurationScope(Scope.AM)
  public static final String YARN_ATS_ACL_SESSION_DOMAIN_ID = TEZ_PREFIX
      + "yarn.ats.acl.session.domain.id";
  @ConfigurationScope(Scope.DAG)
  public static final String YARN_ATS_ACL_DAG_DOMAIN_ID = TEZ_PREFIX
      + "yarn.ats.acl.dag.domain.id";

  /**
   * Boolean value. Enable recovery of DAGs. This allows a restarted app master to recover the 
   * incomplete DAGs from the previous instance of the app master.
   */
  @ConfigurationScope(Scope.AM)
  @ConfigurationProperty(type="boolean")
  public static final String DAG_RECOVERY_ENABLED =
      TEZ_PREFIX + "dag.recovery.enabled";
  public static final boolean DAG_RECOVERY_ENABLED_DEFAULT = true;

  /**
   * Int value. Size in bytes for the IO buffer size while processing the recovery file.
   * Expert level setting.
   */
  @ConfigurationScope(Scope.AM)
  @ConfigurationProperty(type="integer")
  public static final String DAG_RECOVERY_FILE_IO_BUFFER_SIZE =
      TEZ_PREFIX + "dag.recovery.io.buffer.size";
  public static final int DAG_RECOVERY_FILE_IO_BUFFER_SIZE_DEFAULT = 8192;

  /**
   * Int value. Number of recovery events to buffer before flushing them to the recovery log.
   */
  @ConfigurationScope(Scope.AM)
  @ConfigurationProperty(type="integer")
  public static final String DAG_RECOVERY_MAX_UNFLUSHED_EVENTS =
      TEZ_PREFIX + "dag.recovery.max.unflushed.events";
  public static final int DAG_RECOVERY_MAX_UNFLUSHED_EVENTS_DEFAULT = 100;

  /**
   * Int value. Interval, in seconds, between flushing recovery data to the recovery log.
   */
  @ConfigurationScope(Scope.AM)
  @ConfigurationProperty(type="integer")
  public static final String DAG_RECOVERY_FLUSH_INTERVAL_SECS =
      TEZ_PREFIX + "dag.recovery.flush.interval.secs";
  public static final int DAG_RECOVERY_FLUSH_INTERVAL_SECS_DEFAULT = 30;

  /**
   *  Boolean value. Enable local mode execution in Tez. Enables tasks to run in the same process as
   *  the app master. Primarily used for debugging.
   */
  @ConfigurationScope(Scope.AM)
  @ConfigurationProperty(type="boolean")
  public static final String TEZ_LOCAL_MODE =
    TEZ_PREFIX + "local.mode";

  public static final boolean TEZ_LOCAL_MODE_DEFAULT = false;

  /**
   *  Tez AM Inline Mode flag. Not valid till Tez-684 get checked-in
   */
  @Private
  @ConfigurationScope(Scope.AM)
  @ConfigurationProperty(type="boolean")
  public static final String TEZ_AM_INLINE_TASK_EXECUTION_ENABLED =
    TEZ_AM_PREFIX + "inline.task.execution.enabled";

  /**
   *  Tez AM Inline Mode flag. Not valid till Tez-684 get checked-in
   */
  @Private
  public static final boolean TEZ_AM_INLINE_TASK_EXECUTION_ENABLED_DEFAULT = false;

  /**
   * Int value.
   * The maximium number of tasks running in parallel within the app master process.
   */
  @ConfigurationScope(Scope.AM)
  @ConfigurationProperty(type="integer")
  public static final String TEZ_AM_INLINE_TASK_EXECUTION_MAX_TASKS =
    TEZ_AM_PREFIX + "inline.task.execution.max-tasks";

  public static final int TEZ_AM_INLINE_TASK_EXECUTION_MAX_TASKS_DEFAULT = 1;

  // ACLs related configuration
  // Format supports a comma-separated list of users and groups with the users and groups separated
  // by whitespace. e.g. "user1,user2 group1,group2"
  // All users/groups that have access to do operations on the AM also have access to similar
  // operations on all DAGs within that AM/session.
  // By default, the "owner" i.e. the user who started the session will always have full admin
  // access to the AM. Also, the user that submitted the DAG has full admin access to all operations
  // on that DAG.
  //
  // If no value is specified or an invalid configuration is specified,
  // only the user who submitted the AM and/or DAG can do the appropriate operations.
  // For example, "user1,user2 group1, group2" is an invalid configuration value as splitting by
  // whitespace produces 3 lists instead of 2.

  // If the value specified is "*", all users are allowed to do the operation.

  /**
   * Boolean value. Configuration to enable/disable ACL checks.
   */
  @ConfigurationScope(Scope.AM)
  @ConfigurationProperty(type="boolean")
  public static final String TEZ_AM_ACLS_ENABLED = TEZ_AM_PREFIX + "acls.enabled";
  public static final boolean TEZ_AM_ACLS_ENABLED_DEFAULT = true;

  /**
   * String value. 
   * AM view ACLs. This allows the specified users/groups to view the status of the AM and all DAGs
   * that run within this AM.
   * Comma separated list of users, followed by whitespace, followed by a comma separated list of 
   * groups
   */
  @ConfigurationScope(Scope.AM)
  @ConfigurationProperty
  public static final String TEZ_AM_VIEW_ACLS = TEZ_AM_PREFIX + "view-acls";

  /**
   * String value.
   * AM modify ACLs. This allows the specified users/groups to run modify operations on the AM
   * such as submitting DAGs, pre-warming the session, killing DAGs or shutting down the session.
   * Comma separated list of users, followed by whitespace, followed by a comma separated list of 
   * groups
   */
  @ConfigurationScope(Scope.AM)
  @ConfigurationProperty
  public static final String TEZ_AM_MODIFY_ACLS = TEZ_AM_PREFIX + "modify-acls";

  /**
   * Boolean value.
   * Disable version check between client and AM/DAG. Default false.
   */
  @Private
  @ConfigurationScope(Scope.AM)
  @ConfigurationProperty(type="boolean")
  public static final String TEZ_AM_DISABLE_CLIENT_VERSION_CHECK = TEZ_AM_PREFIX
      + "disable.client-version-check";
  public static final boolean TEZ_AM_DISABLE_CLIENT_VERSION_CHECK_DEFAULT = false;

  /**
   * Boolean value.
   * Allow disabling of Timeline Domains even if Timeline is being used.
   */
  @Private
  @ConfigurationScope(Scope.AM)
  @ConfigurationProperty(type="boolean")
  public static final String TEZ_AM_ALLOW_DISABLED_TIMELINE_DOMAINS = TEZ_PREFIX
      + "allow.disabled.timeline-domains";
  public static final boolean TEZ_AM_ALLOW_DISABLED_TIMELINE_DOMAINS_DEFAULT = false;

  /**
   * String value
   * Tez UI URL template for the application.
   * Expert level setting.
   *
   * The AM will redirect the user to the Tez UI via this url. Template supports the following
   * parameters to be replaced with the actual runtime information:
   *
   *   __APPLICATION_ID__ : Replaces this with application ID
   *   __HISTORY_URL_BASE__: replaces this with TEZ_HISTORY_URL_BASE
   *
   *   For example, "http://uihost:9001/#/tez-app/__APPLICATION_ID__/ will be replaced to
   *   http://uihost:9001/#/tez-app/application_1421880306565_0001/
   */
  @ConfigurationScope(Scope.AM)
  @ConfigurationProperty
  public static final String TEZ_AM_TEZ_UI_HISTORY_URL_TEMPLATE = TEZ_AM_PREFIX
      + "tez-ui.history-url.template";
  public static final String TEZ_AM_TEZ_UI_HISTORY_URL_TEMPLATE_DEFAULT =
      "__HISTORY_URL_BASE__/#/tez-app/__APPLICATION_ID__";

  /**
   * String value
   * Tez-UI Url base. This gets replaced in the TEZ_AM_TEZ_UI_HISTORY_URL_TEMPLATE
   * ex http://ui-host:9001 or if its hosted with a prefix http://ui-host:9001/~user
   * if the ui is hosted on the default port (80 for http and 443 for https), the port should not
   * be specified.
   */
  @ConfigurationScope(Scope.AM)
  @ConfigurationProperty
  public static final String TEZ_HISTORY_URL_BASE = TEZ_PREFIX
      + "tez-ui.history-url.base";

  /**
   * String value
   * Allow disabling of the Tez AM webservice. If set to false the Tez-UI wont show progress
   * updates for running application.
   */
  @ConfigurationScope(Scope.AM)
  @ConfigurationProperty(type="boolean")
  public static final String TEZ_AM_WEBSERVICE_ENABLE = TEZ_AM_PREFIX
      + "tez-ui.webservice.enable";
  public static final boolean TEZ_AM_WEBSERVICE_ENABLE_DEFAULT = true;

  // TODO only validate property here, value can also be validated if necessary
  public static void validateProperty(String property, Scope usedScope) {
    Scope validScope = PropertyScope.get(property);
    if (validScope == null) {
      if (LOG.isDebugEnabled()) {
        LOG.debug(property + " is not standard configuration property of tez, can not been validated");
      }
    } else {
      if (usedScope.ordinal() > validScope.ordinal()) {
        throw new IllegalStateException(property + " is set at the scope of " + usedScope
            + ", but it is only valid in the scope of " + validScope);
      }
    }
  }

  @VisibleForTesting
  static Set<String> getPropertySet() {
    return PropertyScope.keySet();
  }

  /**
   * Long value
   * Status Poll interval in Milliseconds used when getting DAG status with timeout.
   */
  @ConfigurationScope(Scope.DAG)
  @ConfigurationProperty(type="long")
  public static final String TEZ_DAG_STATUS_POLLINTERVAL_MS = TEZ_PREFIX
      + "dag.status.pollinterval-ms";
  public static final long TEZ_DAG_STATUS_POLLINTERVAL_MS_DEFAULT = 500;

  /**
   * Long value.
   * Time to wait (in seconds) for apps to complete on MiniTezCluster shutdown.
   */
  @Private
  @ConfigurationScope(Scope.TEST)
  @ConfigurationProperty(type="long")
  public static final String TEZ_TEST_MINI_CLUSTER_APP_WAIT_ON_SHUTDOWN_SECS =
      TEZ_PREFIX + "test.minicluster.app.wait.on.shutdown.secs";
  public static final long TEZ_TEST_MINI_CLUSTER_APP_WAIT_ON_SHUTDOWN_SECS_DEFAULT = 30;

  /**
   * Long value
   * Time to wait (in milliseconds) for yarn app's diagnotics is available
   * Workaround for YARN-2560
   */
  @Private
  @ConfigurationScope(Scope.CLIENT)
  @ConfigurationProperty(type="long")
  public static final String TEZ_CLIENT_DIAGNOSTICS_WAIT_TIMEOUT_MS =
      TEZ_PREFIX + "client.diagnostics.wait.timeout-ms";
  @Private
  public static final long TEZ_CLIENT_DIAGNOSTICS_WAIT_TIMEOUT_MS_DEFAULT = 3*1000;

  /**
   * String value.
   * Ability to provide a different implementation to check/verify java opts defined
   * for vertices/tasks.
   * Class has to be an instance of JavaOptsChecker
   */
  @Private
  @ConfigurationScope(Scope.CLIENT)
  @ConfigurationProperty
  public static final String TEZ_CLIENT_JAVA_OPTS_CHECKER_CLASS =
      TEZ_PREFIX + "java.opts.checker.class";

  /**
   * Boolean value. Default true.
   * Ability to disable the Java Opts Checker
   */
  @Private
  @ConfigurationScope(Scope.CLIENT)
  @ConfigurationProperty(type="boolean")
  public static final String TEZ_CLIENT_JAVA_OPTS_CHECKER_ENABLED =
      TEZ_PREFIX + "java.opts.checker.enabled";
  public static final boolean TEZ_CLIENT_JAVA_OPTS_CHECKER_ENABLED_DEFAULT = true;

  /**
   * Long value. Time interval, in milliseconds, for client to wait during client-requested
   * AM shutdown before issuing a hard kill to the RM for this application.
   * Expert level setting.
   */
  @ConfigurationScope(Scope.CLIENT)
  @ConfigurationProperty(type="long")
  public static final String TEZ_CLIENT_HARD_KILL_TIMEOUT_MS = TEZ_PREFIX + "client.timeout-ms";
  public static final long TEZ_CLIENT_HARD_KILL_TIMEOUT_MS_DEFAULT = 30 * 1000L;

  /**
   * Boolean value. Backwards compatibility setting. Changes TezClient stop to be a
   * synchronous call waiting until AM is in a final state before returning to the user.
   * Expert level setting.
   */
  @ConfigurationScope(Scope.CLIENT)
  @ConfigurationProperty(type="boolean")
  public static final String TEZ_CLIENT_ASYNCHRONOUS_STOP = TEZ_PREFIX + "client.asynchronous-stop";
  public static final boolean TEZ_CLIENT_ASYNCHRONOUS_STOP_DEFAULT = true;

  /**
   * Int value. SubmitDAGPlanRequest cannot be larger than Max IPC message size minus this number; otherwise, it will
   * be serialized to HDFS and we transfer the path to server. Server will deserialize the request from HDFS.
   */
  @Private
  @ConfigurationScope(Scope.CLIENT)
  @ConfigurationProperty(type="int")
  public static final String TEZ_IPC_PAYLOAD_RESERVED_BYTES = TEZ_PREFIX + "ipc.payload.reserved.bytes";
  public static final int TEZ_IPC_PAYLOAD_RESERVED_BYTES_DEFAULT = 5 * 1024 * 1024;

  // for Recovery Test
  @Private
  @ConfigurationScope(Scope.TEST)
  public static final String TEZ_AM_RECOVERY_SERVICE_CLASS =
      TEZ_PREFIX + "test.recovery-service-class";
  @Private
  public static final String TEZ_AM_RECOVERY_SERVICE_CLASS_DEFAULT = "org.apache.tez.dag.history.recovery.RecoveryService";

  /**
   * Boolean value. Default false.
   * By default, configured values for the Summary Entity Types for Timeline will
   * not be respected and be overridden by the Timeline History Service.
   */
  @Private
  @ConfigurationScope(Scope.AM)
  public static final String TEZ_AM_ATS_V15_OVERRIDE_SUMMARY_TYPES =
      TEZ_PREFIX + "am.ats.v15.override.summary-types";
  public static final boolean TEZ_AM_ATS_V15_OVERRIDE_SUMMARY_TYPES_DEFAULT = true;

   /**
    * Integer value in milliseconds. Default value is 5000 milliseconds.
    * The time for which the AM waits after the final DAG completes or when shutdown is invoked
    * before completing shutdown. This allows a client to retrieve any required info directly from
    * the AM on completion of a DAG.
    */
   @Private
   @ConfigurationScope(Scope.AM)
   public static final String TEZ_AM_SLEEP_TIME_BEFORE_EXIT_MILLIS =
       TEZ_AM_PREFIX + "sleep.time.before.exit.millis";

  /**
   * String value. Determines what JVM properties will be logged for debugging purposes
   * in the AM and Task runtime logs.
   */
  @ConfigurationScope(Scope.AM)
  @ConfigurationProperty
  public static final String TEZ_JVM_SYSTEM_PROPERTIES_TO_LOG  =
      TEZ_PREFIX + "tez.jvm.system-properties-to-log";
  public static final List<String> TEZ_JVM_SYSTEM_PROPERTIES_TO_LOG_DEFAULT =
      Collections.unmodifiableList(Arrays.asList(
          "os.name","os.version","java.home","java.runtime.version",
          "java.vendor","java.version","java.vm.name","java.class.path",
          "java.io.tmpdir","user.dir","user.name"));

  /**
   * Int value. Time interval (in seconds). If the Tez AM does not receive a heartbeat from the
   * client within this time interval, it will kill any running DAG and shut down. Required to
   * re-cycle orphaned Tez applications where the client is no longer alive. A negative value
   * can be set to disable this check. For a positive value, the minimum value is 10 seconds.
   * Values between 0 and 10 seconds will be reset to the minimum value.
   * Only relevant in session mode.
   * This is disabled by default i.e. by default, the Tez AM will go on to
   * complete the DAG and only kill itself after hitting the DAG submission timeout defined by
   * {@link #TEZ_SESSION_AM_DAG_SUBMIT_TIMEOUT_SECS}
   */
  @ConfigurationScope(Scope.AM)
  @ConfigurationProperty(type="integer")
  public static final String TEZ_AM_CLIENT_HEARTBEAT_TIMEOUT_SECS =
      TEZ_PREFIX + "am.client.heartbeat.timeout.secs";
  public static final int TEZ_AM_CLIENT_HEARTBEAT_TIMEOUT_SECS_DEFAULT = -1;


  @Private
  @ConfigurationScope(Scope.AM)
  public static final String TEZ_AM_CLIENT_HEARTBEAT_POLL_INTERVAL_MILLIS =
      TEZ_PREFIX + "am.client.heartbeat.poll.interval.millis";
  public static final int TEZ_AM_CLIENT_HEARTBEAT_POLL_INTERVAL_MILLIS_DEFAULT = -1;

}