Mingliang Liu created HADOOP-14214:
--------------------------------------
Summary: 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
Reporter: Mingliang Liu
Assignee: Mingliang Liu
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.
The {{DomainSocketWatcher::delete()} has similar code logic and should suffer
from similar problems.
Thanks [~jdere] for testing and reporting this.
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