org.apache.hadoop.util.InstrumentedReadLock Maven / Gradle / Ivy
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* 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.util.concurrent.locks.ReentrantReadWriteLock;
import org.apache.hadoop.classification.InterfaceAudience;
import org.apache.hadoop.classification.InterfaceStability;
import org.apache.hadoop.thirdparty.com.google.common.annotations.VisibleForTesting;
import org.slf4j.Logger;
/**
* This is a wrap class of a ReadLock.
* It extends the class {@link InstrumentedLock}, and can be used to track
* whether a specific read lock is being held for too long and log
* warnings if so.
*
* The logged warnings are throttled so that logs are not spammed.
*/
@InterfaceAudience.Private
@InterfaceStability.Unstable
public class InstrumentedReadLock extends InstrumentedLock {
private final ReentrantReadWriteLock readWriteLock;
/**
* Uses the ThreadLocal to keep the time of acquiring locks since
* there can be multiple threads that hold the read lock concurrently.
*/
private final ThreadLocal readLockHeldTimeStamp =
new ThreadLocal() {
@Override
protected Long initialValue() {
return Long.MAX_VALUE;
};
};
public InstrumentedReadLock(String name, Logger logger,
ReentrantReadWriteLock readWriteLock,
long minLoggingGapMs, long lockWarningThresholdMs) {
this(name, logger, readWriteLock, minLoggingGapMs, lockWarningThresholdMs,
new Timer());
}
@VisibleForTesting
InstrumentedReadLock(String name, Logger logger,
ReentrantReadWriteLock readWriteLock,
long minLoggingGapMs, long lockWarningThresholdMs, Timer clock) {
super(name, logger, readWriteLock.readLock(), minLoggingGapMs,
lockWarningThresholdMs, clock);
this.readWriteLock = readWriteLock;
}
@Override
public void unlock() {
boolean needReport = readWriteLock.getReadHoldCount() == 1;
long localLockReleaseTime = getTimer().monotonicNow();
long localLockAcquireTime = readLockHeldTimeStamp.get();
getLock().unlock();
if (needReport) {
readLockHeldTimeStamp.remove();
check(localLockAcquireTime, localLockReleaseTime, true);
}
}
/**
* Starts timing for the instrumented read lock.
* It records the time to ThreadLocal.
*/
@Override
protected void startLockTiming() {
if (readWriteLock.getReadHoldCount() == 1) {
readLockHeldTimeStamp.set(getTimer().monotonicNow());
}
}
}