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https://issues.apache.org/jira/browse/LOG4J2-1221?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15069749#comment-15069749
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Remko Popma edited comment on LOG4J2-1221 at 12/23/15 3:38 PM:
---------------------------------------------------------------
After thinking about this some more, you may want to start logging
synchronously a little bit _before_ the queue is completely full (to prevent
race conditions where multiple threads see a remaining slot in the queue and
all try to add an event).
Here is a slight modification to the above example:
{code}
public EventRoute getRoute(final long backgroundThreadId, final Level
level, final int queueSize,
final int queueRemainingCapacity) {
// start logging synchronously when the queue is 94% full, otherwise
log asynchronously
return queueRemainingCapacity <= fractionOf(queueSize) ?
EventRoute.SYNCHRONOUS : EventRoute.ENQUEUE;
}
private int fractionOf(int queueSize) {
return queueSize >> 4; // quick divide by 16: 1/16 ~= 6%
}
{code}
was (Author: rem...@yahoo.com):
After thinking about this some more, you may want to start logging
synchronously a little bit _before_ the queue is completely full (to prevent
race conditions where multiple threads see a remaining slot in the queue and
all try to add an event).
Here is a slight modification to the above example:
{code}
public EventRoute getRoute(final long backgroundThreadId, final Level
level, final int queueSize,
final int queueRemainingCapacity) {
// start logging synchronously when the queue is 94% full, otherwise
log asynchronously
return queueRemainingCapacity == fractionOf(queueSize) ?
EventRoute.SYNCHRONOUS : EventRoute.ENQUEUE;
}
private int fractionOf(int queueSize) {
return queueSize >> 4; // quick divide by 16: 1/16 ~= 6%
}
{code}
> Dead lock observed in BlockingWaitStrategy in Log 4J
> ----------------------------------------------------
>
> Key: LOG4J2-1221
> URL: https://issues.apache.org/jira/browse/LOG4J2-1221
> Project: Log4j 2
> Issue Type: Bug
> Components: Core
> Affects Versions: 2.2
> Environment: log4J Version : 2.2 Disruptor Version : 3.3.2
> Ring Buffer Size : 128
> OS Version :
> cat /etc/release
> Oracle Solaris 11.2 X86
> Java Version
> java version "1.7.0_45"
> Java(TM) SE Runtime Environment (build 1.7.0_45-b18)
> Java HotSpot(TM) Server VM (build 24.45-b08, mixed mode)
> Reporter: Sampath Kumar
> Priority: Critical
> Labels: patch
> Fix For: 2.5.1
>
> Attachments: log4j2-test.xml
>
>
> We have seen this behavior in during high load. Where Logging Got Stropped
> and Application Went to not responsive state.
> log4J Version : 2.2 Disruptor Version : 3.3.2
> Ring Buffer Size : 128
> Producer(Multiples Threads) and Consumer Threads(Single Thread As per Log 4J
> Configuration) Started Waiting on each other.
> Here is the one of the Trace from Thread Dump:
> Producer :
> "[ACTIVE] ExecuteThread: '7' for queue: 'weblogic.kernel.Default
> (self-tuning)'" TIMED_WAITING
> sun.misc.Unsafe.park(Native Method)
> java.util.concurrent.locks.LockSupport.parkNanos(LockSupport.java:349)
> com.lmax.disruptor.MultiProducerSequencer.next(MultiProducerSequencer.java:136)
> com.lmax.disruptor.MultiProducerSequencer.next(MultiProducerSequencer.java:105)
> com.lmax.disruptor.RingBuffer.publishEvent(RingBuffer.java:444)
> com.lmax.disruptor.dsl.Disruptor.publishEvent(Disruptor.java:256)
> org.apache.logging.log4j.core.async.AsyncLogger.logMessage(AsyncLogger.java:285)
> org.apache.logging.log4j.spi.AbstractLogger.logMessage(AbstractLogger.java:722)
> org.apache.logging.log4j.spi.AbstractLogger.logIfEnabled(AbstractLogger.java:693)
> org.apache.logging.log4j.jcl.Log4jLog.debug(Log4jLog.java:81)
> Consumer Thread :
> "AsyncLogger-1" waiting for lock
> java.util.concurrent.locks.AbstractQueuedSynchronizer$ConditionObject@5d972983
> WAITING
> sun.misc.Unsafe.park(Native Method)
> java.util.concurrent.locks.LockSupport.park(LockSupport.java:186)
> java.util.concurrent.locks.AbstractQueuedSynchronizer$ConditionObject.await(AbstractQueuedSynchronizer.java:2043)
> com.lmax.disruptor.BlockingWaitStrategy.waitFor(BlockingWaitStrategy.java:45)
> com.lmax.disruptor.ProcessingSequenceBarrier.waitFor(ProcessingSequenceBarrier.java:55)
> com.lmax.disruptor.BatchEventProcessor.run(BatchEventProcessor.java:123)
> java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1145)
> java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615)
> java.lang.Thread.run(Thread.java:744)
> Is this is known issue which got already fixed in recent build ?
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