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https://issues.apache.org/jira/browse/HADOOP-14214?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15937522#comment-15937522
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Sergey Shelukhin edited comment on HADOOP-14214 at 3/23/17 1:28 AM:
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Hmm.. the reason we are interrupting the thread in question is because we want
it to be interrupted (because the work it's performing is no longer relevant).
Wouldn't this just cause it to be stuck forever anyway, or at best to continue
a useless operation? cc [~sseth]
was (Author: sershe):
Hmm.. the reason we are interrupting the thread in question is because we want
it to be interrupted (because the work it's performing is no longer relevant).
Wouldn't this just cause it to be stuck forever anyway, or at best to continue
a useless operation?
> DomainSocketWatcher::add()/delete() should not self interrupt while looping
> await()
> -----------------------------------------------------------------------------------
>
> Key: HADOOP-14214
> URL: https://issues.apache.org/jira/browse/HADOOP-14214
> Project: Hadoop Common
> Issue Type: Bug
> Components: hdfs-client
> Reporter: Mingliang Liu
> Assignee: Mingliang Liu
> Priority: Critical
> Attachments: HADOOP-14214.000.patch
>
>
> Our hive team found a TPCDS job whose queries running on LLAP seem to be
> getting stuck. Dozens of threads were waiting for the
> {{DfsClientShmManager::lock}}, as following jstack:
> {code}
> Thread 251 (IO-Elevator-Thread-5):
> State: WAITING
> Blocked count: 3871
> Wtaited count: 4565
> Waiting on
> java.util.concurrent.locks.AbstractQueuedSynchronizer$ConditionObject@16ead198
> Stack:
> sun.misc.Unsafe.park(Native Method)
> java.util.concurrent.locks.LockSupport.park(LockSupport.java:175)
>
> java.util.concurrent.locks.AbstractQueuedSynchronizer$ConditionObject.awaitUninterruptibly(AbstractQueuedSynchronizer.java:1976)
>
> org.apache.hadoop.hdfs.shortcircuit.DfsClientShmManager$EndpointShmManager.allocSlot(DfsClientShmManager.java:255)
>
> org.apache.hadoop.hdfs.shortcircuit.DfsClientShmManager.allocSlot(DfsClientShmManager.java:434)
>
> org.apache.hadoop.hdfs.shortcircuit.ShortCircuitCache.allocShmSlot(ShortCircuitCache.java:1017)
>
> org.apache.hadoop.hdfs.BlockReaderFactory.createShortCircuitReplicaInfo(BlockReaderFactory.java:476)
>
> org.apache.hadoop.hdfs.shortcircuit.ShortCircuitCache.create(ShortCircuitCache.java:784)
>
> org.apache.hadoop.hdfs.shortcircuit.ShortCircuitCache.fetchOrCreate(ShortCircuitCache.java:718)
>
> org.apache.hadoop.hdfs.BlockReaderFactory.getBlockReaderLocal(BlockReaderFactory.java:422)
>
> org.apache.hadoop.hdfs.BlockReaderFactory.build(BlockReaderFactory.java:333)
>
> org.apache.hadoop.hdfs.DFSInputStream.actualGetFromOneDataNode(DFSInputStream.java:1181)
>
> org.apache.hadoop.hdfs.DFSInputStream.fetchBlockByteRange(DFSInputStream.java:1118)
> org.apache.hadoop.hdfs.DFSInputStream.pread(DFSInputStream.java:1478)
> org.apache.hadoop.hdfs.DFSInputStream.read(DFSInputStream.java:1441)
> org.apache.hadoop.fs.FSInputStream.readFully(FSInputStream.java:121)
>
> org.apache.hadoop.fs.FSDataInputStream.readFully(FSDataInputStream.java:111)
>
> org.apache.orc.impl.RecordReaderUtils$DefaultDataReader.readStripeFooter(RecordReaderUtils.java:166)
>
> org.apache.hadoop.hive.llap.io.metadata.OrcStripeMetadata.<init>(OrcStripeMetadata.java:64)
>
> org.apache.hadoop.hive.llap.io.encoded.OrcEncodedDataReader.readStripesMetadata(OrcEncodedDataReader.java:622)
> {code}
> The thread that is expected to signal those threads is calling
> {{DomainSocketWatcher::add()}} method, but it gets stuck there dealing with
> InterruptedException infinitely. The jstack is like:
> {code}
> Thread 44417 (TezTR-257387_2840_12_10_52_0):
> State: RUNNABLE
> Blocked count: 3
> Wtaited count: 5
> Stack:
> java.lang.Throwable.fillInStackTrace(Native Method)
> java.lang.Throwable.fillInStackTrace(Throwable.java:783)
> java.lang.Throwable.<init>(Throwable.java:250)
> java.lang.Exception.<init>(Exception.java:54)
> java.lang.InterruptedException.<init>(InterruptedException.java:57)
>
> java.util.concurrent.locks.AbstractQueuedSynchronizer$ConditionObject.await(AbstractQueuedSynchronizer.java:2034)
>
> org.apache.hadoop.net.unix.DomainSocketWatcher.add(DomainSocketWatcher.java:325)
>
> org.apache.hadoop.hdfs.shortcircuit.DfsClientShmManager$EndpointShmManager.allocSlot(DfsClientShmManager.java:266)
>
> org.apache.hadoop.hdfs.shortcircuit.DfsClientShmManager.allocSlot(DfsClientShmManager.java:434)
>
> org.apache.hadoop.hdfs.shortcircuit.ShortCircuitCache.allocShmSlot(ShortCircuitCache.java:1017)
>
> org.apache.hadoop.hdfs.BlockReaderFactory.createShortCircuitReplicaInfo(BlockReaderFactory.java:476)
>
> org.apache.hadoop.hdfs.shortcircuit.ShortCircuitCache.create(ShortCircuitCache.java:784)
>
> org.apache.hadoop.hdfs.shortcircuit.ShortCircuitCache.fetchOrCreate(ShortCircuitCache.java:718)
>
> org.apache.hadoop.hdfs.BlockReaderFactory.getBlockReaderLocal(BlockReaderFactory.java:422)
>
> org.apache.hadoop.hdfs.BlockReaderFactory.build(BlockReaderFactory.java:333)
>
> org.apache.hadoop.hdfs.DFSInputStream.actualGetFromOneDataNode(DFSInputStream.java:1181)
>
> org.apache.hadoop.hdfs.DFSInputStream.fetchBlockByteRange(DFSInputStream.java:1118)
> org.apache.hadoop.hdfs.DFSInputStream.pread(DFSInputStream.java:1478)
> org.apache.hadoop.hdfs.DFSInputStream.read(DFSInputStream.java:1441)
> org.apache.hadoop.fs.FSInputStream.readFully(FSInputStream.java:121)
> {code}
> The whole job makes no progress because of this.
> The thread in {{DomainSocketWatcher::add()}} is expected to eventually break
> the while loop where it waits for the newly added entry being deleted by
> another thread. However, if this thread is ever interrupted, chances are that
> it will hold the lock forever so {{if(!toAdd.contains(entry))}} always be
> false.
> {code:title=DomainSocketWatcher::add()}
> public void add(DomainSocket sock, Handler handler) {
> lock.lock();
> try {
> ......
> toAdd.add(entry);
> kick();
> while (true) {
> try {
> processedCond.await();
> } catch (InterruptedException e) {
> Thread.currentThread().interrupt();
> }
> if (!toAdd.contains(entry)) {
> break;
> }
> }
> } finally {
> lock.unlock();
> }
> }
> {code}
> The reason here is that, this method catches the InterruptedException and
> self interrupts during await(). The await() method internally calls
> {{AbstractQueuedSynchronizer::await()}}, which will throw a new
> InterruptedException if it's interrupted.
> {code:title=AbstractQueuedSynchronizer::await()}
> public final void await() throws InterruptedException {
> if (Thread.interrupted())
> throw new InterruptedException();
> Node node = addConditionWaiter();
> ...
> {code}
> Our code in {{DomainSocketWatcher::add()}} catches this exception (again) and
> self interrupt (again). Please note in this process, the associated lock is
> never released so that the other thread which is supposed to make
> {{if(!toAdd.contains(entry))}} be true is still pending on the lock.
> {{DomainSocketWatcher::delete()}} has similar code logic and should suffer
> from similar problems.
> Thanks [~jdere] for testing and reporting this.
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