asmhatreandClaude Sonnet 5
2f88734f5d
MaxRAMPercentage vs a hardcoded -Xmx, -XX:-UseContainerSupport, the ActiveProcessorCount lie, and which diagnostic flags are worth leaving on in prod, verified in real Docker containers on JDK 25 and JDK 27. Co-Authored-By: Claude Sonnet 5 <[email protected]>
24 lines
1.1 KiB
Plaintext
24 lines
1.1 KiB
Plaintext
$ docker run --rm --memory=256m -v $PWD/docker/memoryhog.jar:/memoryhog.jar --entrypoint java flags-demo:jdk25-jdk \
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-XX:MaxRAMPercentage=75 -XX:+HeapDumpOnOutOfMemoryError -XX:HeapDumpPath=/dumps/heap.hprof \
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-cp /memoryhog.jar MemoryHog 24 200
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=== Diagnostic: -XX:+HeapDumpOnOutOfMemoryError actually leaves a dump behind ===
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MemoryHog starting: chunk=24MB sleep=200ms
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held=24MB heapUsed=25MB heapMax=185MB freeHeap=6MB
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held=48MB heapUsed=49MB heapMax=185MB freeHeap=6MB
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held=72MB heapUsed=73MB heapMax=185MB freeHeap=27MB
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held=96MB heapUsed=98MB heapMax=185MB freeHeap=14MB
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held=120MB heapUsed=122MB heapMax=185MB freeHeap=24MB
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held=144MB heapUsed=146MB heapMax=185MB freeHeap=35MB
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held=168MB heapUsed=170MB heapMax=185MB freeHeap=11MB
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java.lang.OutOfMemoryError: Java heap space
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Dumping heap to /dumps/heap.hprof ...
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Heap dump file created [180390818 bytes in 1.028 secs]
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Exception in thread "main" java.lang.OutOfMemoryError: Java heap space
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at MemoryHog.main(MemoryHog.java:21)
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exit=1
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total 176176
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drwxr-xr-x 2 root root 4096 Oct 1 04:29 .
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drwxr-xr-x 3 root root 4096 Oct 1 04:29 ..
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-rw------- 1 root root 180390818 Oct 1 04:29 heap.hprof
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