[jira] [Resolved] (LOG4J2-2940) High CPU at Java 11 due to the use of StackWalker from StackLocator.getCallerClass

["Carter Kozak (Jira)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/LOG4J2-2940?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Carter Kozak resolved LOG4J2-2940.
----------------------------------
    Resolution: Fixed

> Isn't this now resolved?

I think we can consider it resolved – I expect that we're still spending more cycles than java 8 when the ClassLoaderContextSelector (default) and AsyncLoggerContextSelector are used, but it's half as expensive as it was prior to my changes. BasicContextSelector and the new BasicAsyncLoggerContextSelector definitely solve the problem when they're used.

> High CPU at Java 11 due to the use of StackWalker from StackLocator.getCallerClass
> ----------------------------------------------------------------------------------
>
>                 Key: LOG4J2-2940
>                 URL: https://issues.apache.org/jira/browse/LOG4J2-2940
>             Project: Log4j 2
>          Issue Type: Bug
>          Components: API
>    Affects Versions: 2.13.3
>            Reporter: Peter H
>            Assignee: Ralph Goers
>            Priority: Major
>
> We're encountering an issue similar to [LOG4J2-2792] and [LOG4J2-2880] but it isn't because of the use of Location, but because of the use of dynamically created loggers that we then refer to via {{org.slf4j.LoggerFactory.getLogger(method.getDeclaringClass())}}. This attempts to get the caller class and ends up walking the stack as in the stack trace example below. This is known to be rather problematic (from the performance perspective) and even becomes worse with the time (until the JVM restart, or full GC) - https://bugs.openjdk.java.net/browse/JDK-8222942 for example.
> However instead of doing it this rather expensive way, it may be possible to use an improved approach similar to what jboss-logging library developers used when working on the following issues:
> https://bugzilla.redhat.com/show_bug.cgi?id=1813436
> https://issues.redhat.com/browse/LOGMGR-263
> The related commit: https://github.com/jboss-logging/jboss-logmanager/commit/fc1fc3b509df9797ff06a423878a5b113f6281f8
> Can you check whether something useful may be brought in from that?
> {noformat}at java.lang.StackStreamFactory$AbstractStackWalker.fetchStackFrames(java.base@11.0.8/Native Method)
> at java.lang.StackStreamFactory$AbstractStackWalker.fetchStackFrames(java.base@11.0.8/StackStreamFactory.java:386)
> at java.lang.StackStreamFactory$AbstractStackWalker.getNextBatch(java.base@11.0.8/StackStreamFactory.java:322)
> at java.lang.StackStreamFactory$AbstractStackWalker.peekFrame(java.base@11.0.8/StackStreamFactory.java:263)
> at java.lang.StackStreamFactory$AbstractStackWalker.hasNext(java.base@11.0.8/StackStreamFactory.java:351)
> at java.lang.StackStreamFactory$StackFrameTraverser.tryAdvance(java.base@11.0.8/StackStreamFactory.java:593)
> at java.util.stream.ReferencePipeline.forEachWithCancel(java.base@11.0.8/ReferencePipeline.java:127)
> at java.util.stream.AbstractPipeline.copyIntoWithCancel(java.base@11.0.8/AbstractPipeline.java:502)
> at java.util.stream.AbstractPipeline.copyInto(java.base@11.0.8/AbstractPipeline.java:488)
> at java.util.stream.AbstractPipeline.wrapAndCopyInto(java.base@11.0.8/AbstractPipeline.java:474)
> at java.util.stream.FindOps$FindOp.evaluateSequential(java.base@11.0.8/FindOps.java:150)
> at java.util.stream.AbstractPipeline.evaluate(java.base@11.0.8/AbstractPipeline.java:234)
> at java.util.stream.ReferencePipeline.findFirst(java.base@11.0.8/ReferencePipeline.java:543)
> at org.apache.logging.log4j.util.StackLocator.lambda$getCallerClass$6(StackLocator.java:58)
> at org.apache.logging.log4j.util.StackLocator$$Lambda$1226/0x00000008414fec40.apply(Unknown Source)
> at java.lang.StackStreamFactory$StackFrameTraverser.consumeFrames(java.base@11.0.8/StackStreamFactory.java:534)
> at java.lang.StackStreamFactory$AbstractStackWalker.doStackWalk(java.base@11.0.8/StackStreamFactory.java:306)
> at java.lang.StackStreamFactory$AbstractStackWalker.callStackWalk(java.base@11.0.8/Native Method)
> at java.lang.StackStreamFactory$AbstractStackWalker.beginStackWalk(java.base@11.0.8/StackStreamFactory.java:370)
> at java.lang.StackStreamFactory$AbstractStackWalker.walk(java.base@11.0.8/StackStreamFactory.java:243)
> at java.lang.StackWalker.walk(java.base@11.0.8/StackWalker.java:498)
> at org.apache.logging.log4j.util.StackLocator.getCallerClass(StackLocator.java:57)
> at org.apache.logging.log4j.util.StackLocatorUtil.getCallerClass(StackLocatorUtil.java:67)
> at org.apache.logging.slf4j.Log4jLoggerFactory.getContext(Log4jLoggerFactory.java:45)
> at org.apache.logging.log4j.spi.AbstractLoggerAdapter.getLogger(AbstractLoggerAdapter.java:48)
> at org.apache.logging.slf4j.Log4jLoggerFactory.getLogger(Log4jLoggerFactory.java:30)
> at org.slf4j.LoggerFactory.getLogger(LoggerFactory.java:363)
> at org.slf4j.LoggerFactory.getLogger(LoggerFactory.java:388)
> at LoggerAspect.isLogLevelEnabled(LoggerAspect.java:91)
> ...{noformat}



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