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Blockhound detects a blocking call inside GlobalEventExecutor#addTask

See original GitHub issue

Expected behavior

No blocking calls detected by BlockHound.

Actual behavior

I observe the same problem originally reported by @62mkv in https://github.com/reactor/reactor-netty/issues/1086:

Occasionally, BlockHound-enabled Spring Boot (w/WebFlux) test suite fails to complete correctly because of such exception w/ the following trace:

18:03:03.327 [reactor-http-nio-2] ERROR io.netty.util.concurrent.DefaultPromise.rejectedExecution - Failed to submit a listener notification task. Event loop shut down?
reactor.blockhound.BlockingOperationError: Blocking call! sun.misc.Unsafe#park
        at sun.misc.Unsafe.park(Unsafe.java)
        at java.util.concurrent.locks.LockSupport.park(LockSupport.java:175)
        at java.util.concurrent.locks.AbstractQueuedSynchronizer.parkAndCheckInterrupt(AbstractQueuedSynchronizer.java:836)
        at java.util.concurrent.locks.AbstractQueuedSynchronizer.acquireQueued(AbstractQueuedSynchronizer.java:870)
        at java.util.concurrent.locks.AbstractQueuedSynchronizer.acquire(AbstractQueuedSynchronizer.java:1199)
        at java.util.concurrent.locks.ReentrantLock$NonfairSync.lock(ReentrantLock.java:209)
        at java.util.concurrent.locks.ReentrantLock.lock(ReentrantLock.java:285)
        at java.util.concurrent.LinkedBlockingQueue.offer(LinkedBlockingQueue.java:418)
        at java.util.AbstractQueue.add(AbstractQueue.java:95)
        at io.netty.util.concurrent.GlobalEventExecutor.addTask(GlobalEventExecutor.java:141)
        at io.netty.util.concurrent.GlobalEventExecutor.execute(GlobalEventExecutor.java:206)
        at io.netty.util.concurrent.DefaultPromise.safeExecute(DefaultPromise.java:841)
        at io.netty.util.concurrent.DefaultPromise.notifyListeners(DefaultPromise.java:498)
        at io.netty.util.concurrent.DefaultPromise.setValue0(DefaultPromise.java:615)
        at io.netty.util.concurrent.DefaultPromise.setSuccess0(DefaultPromise.java:604)
        at io.netty.util.concurrent.DefaultPromise.setSuccess(DefaultPromise.java:96)
        at io.netty.util.concurrent.SingleThreadEventExecutor$4.run(SingleThreadEventExecutor.java:1051)
        at io.netty.util.internal.ThreadExecutorMap$2.run(ThreadExecutorMap.java:74)
        at io.netty.util.concurrent.FastThreadLocalRunnable.run(FastThreadLocalRunnable.java:30)
        at java.lang.Thread.run(Thread.java:748)

reactor-netty maintainer @violetagg suggested the issue should be moved to this project. I haven’t found it here, so I’m opening it.

Workaround

It’s possible to whitelist this directly in the application as a temporary solution:

  private static final class NettyWorkaroundBlockHoundIntegration implements BlockHoundIntegration {
    @Override
    void applyTo(BlockHound.Builder builder) {
      builder.allowBlockingCallsInside(GlobalEventExecutor.class.name, 'addTask')
    }
  }

Netty version

4.1.48.Final

JVM version (e.g. `java -version`)

openjdk version “11.0.4” 2019-07-16

OS version (e.g. `uname -a`)

Mac OS X 10.15.2 x86_64, Win10

Issue Analytics

State:
Created 3 years ago
Reactions:2
Comments:7 (6 by maintainers)

Top GitHub Comments

1reaction

pbetkiercommented, May 7, 2020

sure

0reactions

pbetkiercommented, May 8, 2020

I’ve created a PR, verified it solves my problem after mvn install and using the SNAPSHOT version in my project.

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