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https://issues.apache.org/jira/browse/LOG4J2-2940?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17221342#comment-17221342
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Peter H commented on LOG4J2-2940:
---------------------------------
{quote}... SLF4J adapter's getContext method. It is trying to resolve the
calling class to get its ClassLoader to pass to the above algorithm. This
probably shouldn't be handled this way because it you have chosen to use a
ContextSelector other than ClassLoaderContextSelect than determining the
caller's ClassLoader may be a waste of time. It should probably just pass the
FQCN.{quote}
If that's the case it may be possible to correct the SLF4J adapter's code
(Log4jLoggerFactory?) to handle such cases more efficiently right there.
Correct?
> 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$AbstractStackWalker.fetchStackFrames([email protected]/Native
> Method)
> at
> java.lang.StackStreamFactory$AbstractStackWalker.fetchStackFrames([email protected]/StackStreamFactory.java:386)
> at
> java.lang.StackStreamFactory$AbstractStackWalker.getNextBatch([email protected]/StackStreamFactory.java:322)
> at
> java.lang.StackStreamFactory$AbstractStackWalker.peekFrame([email protected]/StackStreamFactory.java:263)
> at
> java.lang.StackStreamFactory$AbstractStackWalker.hasNext([email protected]/StackStreamFactory.java:351)
> at
> java.lang.StackStreamFactory$StackFrameTraverser.tryAdvance([email protected]/StackStreamFactory.java:593)
> at
> java.util.stream.ReferencePipeline.forEachWithCancel([email protected]/ReferencePipeline.java:127)
> at
> java.util.stream.AbstractPipeline.copyIntoWithCancel([email protected]/AbstractPipeline.java:502)
> at
> java.util.stream.AbstractPipeline.copyInto([email protected]/AbstractPipeline.java:488)
> at
> java.util.stream.AbstractPipeline.wrapAndCopyInto([email protected]/AbstractPipeline.java:474)
> at
> java.util.stream.FindOps$FindOp.evaluateSequential([email protected]/FindOps.java:150)
> at
> java.util.stream.AbstractPipeline.evaluate([email protected]/AbstractPipeline.java:234)
> at
> java.util.stream.ReferencePipeline.findFirst([email protected]/ReferencePipeline.java:543)
> at
> org.apache.logging.log4j.util.StackLocator.lambda$getCallerClass$6(StackLocator.java:58)
> at
> org.apache.logging.log4j.util.StackLocator$$Lambda$1226/0x00000008414fec40.apply(Unknown
> Source)
> at
> java.lang.StackStreamFactory$StackFrameTraverser.consumeFrames([email protected]/StackStreamFactory.java:534)
> at
> java.lang.StackStreamFactory$AbstractStackWalker.doStackWalk([email protected]/StackStreamFactory.java:306)
> at
> java.lang.StackStreamFactory$AbstractStackWalker.callStackWalk([email protected]/Native
> Method)
> at
> java.lang.StackStreamFactory$AbstractStackWalker.beginStackWalk([email protected]/StackStreamFactory.java:370)
> at
> java.lang.StackStreamFactory$AbstractStackWalker.walk([email protected]/StackStreamFactory.java:243)
> at java.lang.StackWalker.walk([email protected]/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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