| /** |
| * 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 org.apache.hadoop.classification.InterfaceAudience; |
| import org.apache.hadoop.classification.InterfaceStability; |
| |
| import java.math.BigInteger; |
| |
| /** |
| * Utility for sampling and computing CPU usage. |
| */ |
| @InterfaceAudience.Private |
| @InterfaceStability.Unstable |
| public class CpuTimeTracker { |
| public static final int UNAVAILABLE = -1; |
| private final long minimumTimeInterval; |
| |
| // CPU used time since system is on (ms) |
| private BigInteger cumulativeCpuTime = BigInteger.ZERO; |
| |
| // CPU used time read last time (ms) |
| private BigInteger lastCumulativeCpuTime = BigInteger.ZERO; |
| |
| // Unix timestamp while reading the CPU time (ms) |
| private long sampleTime; |
| private long lastSampleTime; |
| private float cpuUsage; |
| private BigInteger jiffyLengthInMillis; |
| |
| public CpuTimeTracker(long jiffyLengthInMillis) { |
| this.jiffyLengthInMillis = BigInteger.valueOf(jiffyLengthInMillis); |
| this.cpuUsage = UNAVAILABLE; |
| this.sampleTime = UNAVAILABLE; |
| this.lastSampleTime = UNAVAILABLE; |
| minimumTimeInterval = 10 * jiffyLengthInMillis; |
| } |
| |
| /** |
| * Return percentage of cpu time spent over the time since last update. |
| * CPU time spent is based on elapsed jiffies multiplied by amount of |
| * time for 1 core. Thus, if you use 2 cores completely you would have spent |
| * twice the actual time between updates and this will return 200%. |
| * |
| * @return Return percentage of cpu usage since last update, {@link |
| * CpuTimeTracker#UNAVAILABLE} if there haven't been 2 updates more than |
| * {@link CpuTimeTracker#minimumTimeInterval} apart |
| */ |
| public float getCpuTrackerUsagePercent() { |
| if (lastSampleTime == UNAVAILABLE || |
| lastSampleTime > sampleTime) { |
| // lastSampleTime > sampleTime may happen when the system time is changed |
| lastSampleTime = sampleTime; |
| lastCumulativeCpuTime = cumulativeCpuTime; |
| return cpuUsage; |
| } |
| // When lastSampleTime is sufficiently old, update cpuUsage. |
| // Also take a sample of the current time and cumulative CPU time for the |
| // use of the next calculation. |
| if (sampleTime > lastSampleTime + minimumTimeInterval) { |
| cpuUsage = |
| ((cumulativeCpuTime.subtract(lastCumulativeCpuTime)).floatValue()) |
| * 100F / ((float) (sampleTime - lastSampleTime)); |
| lastSampleTime = sampleTime; |
| lastCumulativeCpuTime = cumulativeCpuTime; |
| } |
| return cpuUsage; |
| } |
| |
| /** |
| * Obtain the cumulative CPU time since the system is on. |
| * @return cumulative CPU time in milliseconds |
| */ |
| public long getCumulativeCpuTime() { |
| return cumulativeCpuTime.longValue(); |
| } |
| |
| /** |
| * Apply delta to accumulators. |
| * @param elapsedJiffies updated jiffies |
| * @param newTime new sample time |
| */ |
| public void updateElapsedJiffies(BigInteger elapsedJiffies, long newTime) { |
| cumulativeCpuTime = elapsedJiffies.multiply(jiffyLengthInMillis); |
| sampleTime = newTime; |
| } |
| |
| @Override |
| public String toString() { |
| StringBuilder sb = new StringBuilder(); |
| sb.append("SampleTime " + this.sampleTime); |
| sb.append(" CummulativeCpuTime " + this.cumulativeCpuTime); |
| sb.append(" LastSampleTime " + this.lastSampleTime); |
| sb.append(" LastCummulativeCpuTime " + this.lastCumulativeCpuTime); |
| sb.append(" CpuUsage " + this.cpuUsage); |
| sb.append(" JiffyLengthMillisec " + this.jiffyLengthInMillis); |
| return sb.toString(); |
| } |
| } |