| /** |
| * 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.hbase.client.backoff; |
| |
| import org.apache.hadoop.conf.Configuration; |
| import org.apache.hadoop.hbase.HConstants; |
| import org.apache.hadoop.hbase.ServerName; |
| import org.apache.yetus.audience.InterfaceAudience; |
| import org.slf4j.Logger; |
| import org.slf4j.LoggerFactory; |
| import org.apache.hbase.thirdparty.com.google.common.base.Preconditions; |
| |
| /** |
| * Simple exponential backoff policy on for the client that uses a percent^4 times the |
| * max backoff to generate the backoff time. |
| */ |
| @InterfaceAudience.Public |
| public class ExponentialClientBackoffPolicy implements ClientBackoffPolicy { |
| |
| private static final Logger LOG = LoggerFactory.getLogger(ExponentialClientBackoffPolicy.class); |
| |
| private static final long ONE_MINUTE = 60 * 1000; |
| public static final long DEFAULT_MAX_BACKOFF = 5 * ONE_MINUTE; |
| public static final String MAX_BACKOFF_KEY = "hbase.client.exponential-backoff.max"; |
| private long maxBackoff; |
| private float heapOccupancyLowWatermark; |
| private float heapOccupancyHighWatermark; |
| |
| public ExponentialClientBackoffPolicy(Configuration conf) { |
| this.maxBackoff = conf.getLong(MAX_BACKOFF_KEY, DEFAULT_MAX_BACKOFF); |
| this.heapOccupancyLowWatermark = conf.getFloat(HConstants.HEAP_OCCUPANCY_LOW_WATERMARK_KEY, |
| HConstants.DEFAULT_HEAP_OCCUPANCY_LOW_WATERMARK); |
| this.heapOccupancyHighWatermark = conf.getFloat(HConstants.HEAP_OCCUPANCY_HIGH_WATERMARK_KEY, |
| HConstants.DEFAULT_HEAP_OCCUPANCY_HIGH_WATERMARK); |
| } |
| |
| @Override |
| public long getBackoffTime(ServerName serverName, byte[] region, ServerStatistics stats) { |
| // no stats for the server yet, so don't backoff |
| if (stats == null) { |
| return 0; |
| } |
| |
| ServerStatistics.RegionStatistics regionStats = stats.getStatsForRegion(region); |
| // no stats for the region yet - don't backoff |
| if (regionStats == null) { |
| return 0; |
| } |
| |
| // Factor in memstore load |
| double percent = regionStats.getMemStoreLoadPercent() / 100.0; |
| |
| // Factor in heap occupancy |
| float heapOccupancy = regionStats.getHeapOccupancyPercent() / 100.0f; |
| |
| // Factor in compaction pressure, 1.0 means heavy compaction pressure |
| float compactionPressure = regionStats.getCompactionPressure() / 100.0f; |
| if (heapOccupancy >= heapOccupancyLowWatermark) { |
| // If we are higher than the high watermark, we are already applying max |
| // backoff and cannot scale more (see scale() below) |
| if (heapOccupancy > heapOccupancyHighWatermark) { |
| heapOccupancy = heapOccupancyHighWatermark; |
| } |
| percent = Math.max(percent, |
| scale(heapOccupancy, heapOccupancyLowWatermark, heapOccupancyHighWatermark, |
| 0.1, 1.0)); |
| } |
| percent = Math.max(percent, compactionPressure); |
| // square the percent as a value less than 1. Closer we move to 100 percent, |
| // the percent moves to 1, but squaring causes the exponential curve |
| double multiplier = Math.pow(percent, 4.0); |
| if (multiplier > 1) { |
| multiplier = 1; |
| } |
| return (long) (multiplier * maxBackoff); |
| } |
| |
| /** Scale valueIn in the range [baseMin,baseMax] to the range [limitMin,limitMax] */ |
| private static double scale(double valueIn, double baseMin, double baseMax, double limitMin, |
| double limitMax) { |
| Preconditions.checkArgument(baseMin <= baseMax, "Illegal source range [%s,%s]", |
| baseMin, baseMax); |
| Preconditions.checkArgument(limitMin <= limitMax, "Illegal target range [%s,%s]", |
| limitMin, limitMax); |
| Preconditions.checkArgument(valueIn >= baseMin && valueIn <= baseMax, |
| "Value %s must be within the range [%s,%s]", valueIn, baseMin, baseMax); |
| return ((limitMax - limitMin) * (valueIn - baseMin) / (baseMax - baseMin)) + limitMin; |
| } |
| } |