| /** |
| * 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.hadoop.util; |
| |
| import java.io.IOException; |
| import java.util.Arrays; |
| |
| import org.apache.commons.logging.Log; |
| import org.apache.commons.logging.LogFactory; |
| |
| import org.apache.hadoop.util.Shell.ExitCodeException; |
| import org.apache.hadoop.util.Shell.ShellCommandExecutor; |
| |
| /** |
| * Process tree related operations |
| */ |
| public class ProcessTree { |
| |
| private static final Log LOG = LogFactory.getLog(ProcessTree.class); |
| |
| /** |
| * The constants for the signals. |
| */ |
| public static enum Signal { |
| QUIT(3), KILL(9), TERM(15); |
| private int value; |
| private Signal(int value) { |
| this.value = value; |
| } |
| public int getValue() { |
| return value; |
| } |
| } |
| |
| public static final boolean isSetsidAvailable = isSetsidSupported(); |
| private static boolean isSetsidSupported() { |
| ShellCommandExecutor shexec = null; |
| boolean setsidSupported = true; |
| try { |
| String[] args = {"setsid", "bash", "-c", "echo $$"}; |
| shexec = new ShellCommandExecutor(args); |
| shexec.execute(); |
| } catch (IOException ioe) { |
| LOG.warn("setsid is not available on this machine. So not using it."); |
| setsidSupported = false; |
| } finally { // handle the exit code |
| LOG.info("setsid exited with exit code " + shexec.getExitCode()); |
| } |
| return setsidSupported; |
| } |
| |
| /** |
| * Kills the process(OR process group) by sending the signal SIGKILL |
| * in the current thread |
| * @param pid Process id(OR process group id) of to-be-deleted-process |
| * @param isProcessGroup Is pid a process group id of to-be-deleted-processes |
| * @param sleepTimeBeforeSigKill wait time before sending SIGKILL after |
| * sending SIGTERM |
| */ |
| private static void sigKillInCurrentThread(String pid, boolean isProcessGroup, |
| long sleepTimeBeforeSigKill) { |
| // Kill the subprocesses of root process(even if the root process is not |
| // alive) if process group is to be killed. |
| if (isProcessGroup || ProcessTree.isAlive(pid)) { |
| try { |
| // Sleep for some time before sending SIGKILL |
| Thread.sleep(sleepTimeBeforeSigKill); |
| } catch (InterruptedException i) { |
| LOG.warn("Thread sleep is interrupted."); |
| } |
| if(isProcessGroup) { |
| killProcessGroup(pid, Signal.KILL); |
| } else { |
| killProcess(pid, Signal.KILL); |
| } |
| } |
| } |
| |
| /** |
| * Sends signal to process, forcefully terminating the process. |
| * |
| * @param pid process id |
| * @param signal the signal number to send |
| */ |
| public static void killProcess(String pid, Signal signal) { |
| |
| //If process tree is not alive then return immediately. |
| if(!ProcessTree.isAlive(pid)) { |
| return; |
| } |
| String[] args = { "kill", "-" + signal.getValue(), pid }; |
| ShellCommandExecutor shexec = new ShellCommandExecutor(args); |
| try { |
| shexec.execute(); |
| } catch (IOException e) { |
| LOG.warn("Error sending signal " + signal + " to process "+ pid + " ."+ |
| StringUtils.stringifyException(e)); |
| } finally { |
| LOG.info("Killing process " + pid + " with signal " + signal + |
| ". Exit code " + shexec.getExitCode()); |
| } |
| } |
| |
| /** |
| * Sends signal to all process belonging to same process group, |
| * forcefully terminating the process group. |
| * |
| * @param pgrpId process group id |
| * @param signal the signal number to send |
| */ |
| public static void killProcessGroup(String pgrpId, Signal signal) { |
| |
| //If process tree is not alive then return immediately. |
| if(!ProcessTree.isProcessGroupAlive(pgrpId)) { |
| return; |
| } |
| |
| String[] args = { "kill", "-" + signal.getValue() , "-"+pgrpId }; |
| ShellCommandExecutor shexec = new ShellCommandExecutor(args); |
| try { |
| shexec.execute(); |
| } catch (IOException e) { |
| LOG.warn("Error sending signal " + signal + " to process group "+ |
| pgrpId + " ."+ |
| StringUtils.stringifyException(e)); |
| } finally { |
| LOG.info("Killing process group" + pgrpId + " with signal " + signal + |
| ". Exit code " + shexec.getExitCode()); |
| } |
| } |
| |
| /** |
| * Is the process with PID pid still alive? |
| * This method assumes that isAlive is called on a pid that was alive not |
| * too long ago, and hence assumes no chance of pid-wrapping-around. |
| * |
| * @param pid pid of the process to check. |
| * @return true if process is alive. |
| */ |
| public static boolean isAlive(String pid) { |
| ShellCommandExecutor shexec = null; |
| try { |
| String[] args = { "kill", "-0", pid }; |
| shexec = new ShellCommandExecutor(args); |
| shexec.execute(); |
| } catch (ExitCodeException ee) { |
| return false; |
| } catch (IOException ioe) { |
| LOG.warn("Error executing shell command " |
| + Arrays.toString(shexec.getExecString()) + ioe); |
| return false; |
| } |
| return (shexec.getExitCode() == 0 ? true : false); |
| } |
| |
| /** |
| * Is the process group with still alive? |
| * |
| * This method assumes that isAlive is called on a pid that was alive not |
| * too long ago, and hence assumes no chance of pid-wrapping-around. |
| * |
| * @param pgrpId process group id |
| * @return true if any of process in group is alive. |
| */ |
| public static boolean isProcessGroupAlive(String pgrpId) { |
| ShellCommandExecutor shexec = null; |
| try { |
| String[] args = { "kill", "-0", "-"+pgrpId }; |
| shexec = new ShellCommandExecutor(args); |
| shexec.execute(); |
| } catch (ExitCodeException ee) { |
| return false; |
| } catch (IOException ioe) { |
| LOG.warn("Error executing shell command " |
| + Arrays.toString(shexec.getExecString()) + ioe); |
| return false; |
| } |
| return (shexec.getExitCode() == 0 ? true : false); |
| } |
| |
| |
| /** |
| * Helper thread class that kills process-tree with SIGKILL in background |
| */ |
| static class SigKillThread extends Thread { |
| private String pid = null; |
| private boolean isProcessGroup = false; |
| |
| private final long sleepTimeBeforeSigKill; |
| |
| private SigKillThread(String pid, boolean isProcessGroup, long interval) { |
| this.pid = pid; |
| this.isProcessGroup = isProcessGroup; |
| this.setName(this.getClass().getName() + "-" + pid); |
| sleepTimeBeforeSigKill = interval; |
| } |
| |
| public void run() { |
| sigKillInCurrentThread(pid, isProcessGroup, sleepTimeBeforeSigKill); |
| } |
| } |
| } |