+ * 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.hdfs;
+
+import java.util.concurrent.TimeUnit;
+import java.util.concurrent.atomic.AtomicLong;
+import java.util.concurrent.locks.Condition;
+import java.util.concurrent.locks.Lock;
+import java.util.concurrent.locks.ReentrantLock;
+
+import org.apache.hadoop.classification.InterfaceAudience;
+import org.apache.hadoop.classification.InterfaceStability;
+import org.apache.commons.logging.Log;
+import org.apache.hadoop.util.StringUtils;
+import org.apache.hadoop.util.Timer;
+
+import com.google.common.annotations.VisibleForTesting;
+
+/**
+ * This is a debugging class that can be used by callers to track
+ * whether a specifc lock is being held for too long and periodically
+ * log a warning and stack trace, if so.
+ *
+ * The logged warnings are throttled so that logs are not spammed.
+ *
+ * A new instance of InstrumentedLock can be created for each object
+ * that needs to be instrumented.
+ */
+@InterfaceAudience.Private
+@InterfaceStability.Unstable
+public class InstrumentedLock implements Lock {
+
+ private final Lock lock;
+ private final Log logger;
+ private final String name;
+ private final Timer clock;
+
+ /** Minimum gap between two lock warnings. */
+ private final long minLoggingGap;
+ /** Threshold for detecting long lock held time. */
+ private final long lockWarningThreshold;
+
+ // Tracking counters for lock statistics.
+ private volatile long lockAcquireTimestamp;
+ private final AtomicLong lastLogTimestamp;
+ private final AtomicLong warningsSuppressed = new AtomicLong(0);
+
+ /**
+ * Create a instrumented lock instance which logs a warning message
+ * when lock held time is above given threshold.
+ *
+ * @param name the identifier of the lock object
+ * @param logger this class does not have its own logger, will log to the
+ * given logger instead
+ * @param minLoggingGapMs the minimum time gap between two log messages,
+ * this is to avoid spamming to many logs
+ * @param lockWarningThresholdMs the time threshold to view lock held
+ * time as being "too long"
+ */
+ public InstrumentedLock(String name, Log logger, long minLoggingGapMs,
+ long lockWarningThresholdMs) {
+ this(name, logger, new ReentrantLock(),
+ minLoggingGapMs, lockWarningThresholdMs);
+ }
+
+ public InstrumentedLock(String name, Log logger, Lock lock,
+ long minLoggingGapMs, long lockWarningThresholdMs) {
+ this(name, logger, lock,
+ minLoggingGapMs, lockWarningThresholdMs, new Timer());
+ }
+
+ @VisibleForTesting
+ InstrumentedLock(String name, Log logger, Lock lock,
+ long minLoggingGapMs, long lockWarningThresholdMs, Timer clock) {
+ this.name = name;
+ this.lock = lock;
+ this.clock = clock;
+ this.logger = logger;
+ minLoggingGap = minLoggingGapMs;
+ lockWarningThreshold = lockWarningThresholdMs;
+ lastLogTimestamp = new AtomicLong(
+ clock.monotonicNow() - Math.max(minLoggingGap, lockWarningThreshold));
+ }
+
+ @Override
+ public void lock() {
+ lock.lock();
+ lockAcquireTimestamp = clock.monotonicNow();
+ }
+
+ @Override
+ public void lockInterruptibly() throws InterruptedException {
+ lock.lockInterruptibly();
+ lockAcquireTimestamp = clock.monotonicNow();
+ }
+
+ @Override
+ public boolean tryLock() {
+ if (lock.tryLock()) {
+ lockAcquireTimestamp = clock.monotonicNow();
+ return true;
+ }
+ return false;
+ }
+
+ @Override
+ public boolean tryLock(long time, TimeUnit unit) throws InterruptedException {
+ if (lock.tryLock(time, unit)) {
+ lockAcquireTimestamp = clock.monotonicNow();
+ return true;
+ }
+ return false;
+ }
+
+ @Override
+ public void unlock() {
+ long localLockReleaseTime = clock.monotonicNow();
+ long localLockAcquireTime = lockAcquireTimestamp;
+ lock.unlock();
+ check(localLockAcquireTime, localLockReleaseTime);
+ }
+
+ @Override
+ public Condition newCondition() {
+ return lock.newCondition();
+ }
+
+ @VisibleForTesting
+ void logWarning(long lockHeldTime, long suppressed) {
+ logger.warn(String.format("Lock held time above threshold: " +
+ "lock identifier: %s " +
+ "lockHeldTimeMs=%d ms. Suppressed %d lock warnings. " +
+ "The stack trace is: %s" ,
+ name, lockHeldTime, suppressed,
+ StringUtils.getStackTrace(Thread.currentThread())));
+ }
+
+ /**
+ * Log a warning if the lock was held for too long.
+ *
+ * Should be invoked by the caller immediately AFTER releasing the lock.
+ *
+ * @param acquireTime - timestamp just after acquiring the lock.
+ * @param releaseTime - timestamp just before releasing the lock.
+ */
+ private void check(long acquireTime, long releaseTime) {
+ if (!logger.isWarnEnabled()) {
+ return;
+ }
+
+ final long lockHeldTime = releaseTime - acquireTime;
+ if (lockWarningThreshold - lockHeldTime < 0) {
+ long now;
+ long localLastLogTs;
+ do {
+ now = clock.monotonicNow();
+ localLastLogTs = lastLogTimestamp.get();
+ long deltaSinceLastLog = now - localLastLogTs;
+ // check should print log or not
+ if (deltaSinceLastLog - minLoggingGap < 0) {
+ warningsSuppressed.incrementAndGet();
+ return;
+ }
+ } while (!lastLogTimestamp.compareAndSet(localLastLogTs, now));
+ long suppressed = warningsSuppressed.getAndSet(0);
+ logWarning(lockHeldTime, suppressed);
+ }
+ }
+
+}
diff --git a/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/datanode/fsdataset/impl/FsDatasetImpl.java b/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/datanode/fsdataset/impl/FsDatasetImpl.java
index a1c2a46afab..5b3ebceb488 100644
--- a/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/datanode/fsdataset/impl/FsDatasetImpl.java
+++ b/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/datanode/fsdataset/impl/FsDatasetImpl.java
@@ -42,6 +42,7 @@ import java.util.Set;
import java.util.concurrent.ConcurrentHashMap;
import java.util.*;
import java.util.concurrent.Executor;
+import java.util.concurrent.TimeUnit;
import javax.management.NotCompliantMBeanException;
import javax.management.ObjectName;
@@ -62,7 +63,7 @@ import org.apache.hadoop.fs.StorageType;
import org.apache.hadoop.hdfs.DFSConfigKeys;
import org.apache.hadoop.hdfs.DFSUtilClient;
import org.apache.hadoop.hdfs.ExtendedBlockId;
-import org.apache.hadoop.hdfs.HdfsConfiguration;
+import org.apache.hadoop.hdfs.InstrumentedLock;
import org.apache.hadoop.util.AutoCloseableLock;
import org.apache.hadoop.hdfs.protocol.Block;
import org.apache.hadoop.hdfs.protocol.BlockListAsLongs;
@@ -282,7 +283,13 @@ class FsDatasetImpl implements FsDatasetSpi
+ * 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.hdfs;
+
+import java.util.concurrent.atomic.AtomicLong;
+import java.util.concurrent.atomic.AtomicReference;
+import java.util.concurrent.locks.Lock;
+
+import org.apache.hadoop.util.AutoCloseableLock;
+import org.apache.hadoop.util.Timer;
+
+import org.apache.commons.logging.Log;
+import org.apache.commons.logging.LogFactory;
+
+import org.junit.Rule;
+import org.junit.Test;
+import org.junit.rules.TestName;
+import static org.mockito.Mockito.*;
+import static org.junit.Assert.*;
+
+/**
+ * A test class for InstrumentedLock.
+ */
+public class TestInstrumentedLock {
+
+ static final Log LOG = LogFactory.getLog(TestInstrumentedLock.class);
+
+ @Rule public TestName name = new TestName();
+
+ /**
+ * Test exclusive access of the lock.
+ * @throws Exception
+ */
+ @Test(timeout=10000)
+ public void testMultipleThread() throws Exception {
+ String testname = name.getMethodName();
+ final InstrumentedLock lock = new InstrumentedLock(testname, LOG, 0, 300);
+ lock.lock();
+ try {
+ Thread competingThread = new Thread() {
+ @Override
+ public void run() {
+ assertFalse(lock.tryLock());
+ }
+ };
+ competingThread.start();
+ competingThread.join();
+ } finally {
+ lock.unlock();
+ }
+ }
+
+ /**
+ * Test the correctness with try-with-resource syntax.
+ * @throws Exception
+ */
+ @Test(timeout=10000)
+ public void testTryWithResourceSyntax() throws Exception {
+ String testname = name.getMethodName();
+ final AtomicReference