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https://issues.apache.org/jira/browse/LOG4J2-2940?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17252025#comment-17252025
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Ralph Goers commented on LOG4J2-2940:
-------------------------------------
We should a) investigate whether we can a) use StackWalker.getCallerClass()
directly in LoggerFactory.getLogger() as that method is supposed to be much
faster than walking the stack and b) check to see what the overhead of that is.
We may also want to add a method to LogManager to determine if the
ContextSelector requires the ClassLoader, in which case we could skip the call.
> 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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