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]>
32 lines
1.8 KiB
Plaintext
32 lines
1.8 KiB
Plaintext
$ docker run --rm --memory=256m --entrypoint java flags-demo:jdk25 \
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-XX:-UseContainerSupport -XX:+PrintFlagsFinal -version | grep -E "MaxHeapSize|UseContainerSupport"
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$ docker run --rm --memory=256m --entrypoint java flags-demo:jdk25 \
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-Xlog:gc -XX:-UseContainerSupport -cp /memoryhog.jar MemoryHog 24 200
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--- what the flag alone resolves heap to ---
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size_t MaxHeapSize = 2105540608 {product} {ergonomic}
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size_t SoftMaxHeapSize = 2105540608 {manageable} {ergonomic}
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bool UseContainerSupport = false {product} {command line}
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--- the hog run ---
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[0.004s][info][gc] Using G1
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MemoryHog starting: chunk=24MB sleep=200ms
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held=24MB heapUsed=26MB heapMax=2008MB freeHeap=101MB
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held=48MB heapUsed=52MB heapMax=2008MB freeHeap=75MB
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[0.515s][info][gc] GC(0) Pause Young (Concurrent Start) (G1 Humongous Allocation) 52M->51M(128M) 1.445ms
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[0.515s][info][gc] GC(1) Concurrent Undo Cycle
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[0.515s][info][gc] GC(1) Concurrent Undo Cycle 0.084ms
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held=72MB heapUsed=76MB heapMax=2008MB freeHeap=51MB
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[0.731s][info][gc] GC(2) Pause Young (Concurrent Start) (G1 Humongous Allocation) 76M->76M(128M) 1.569ms
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[0.732s][info][gc] GC(3) Concurrent Mark Cycle
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[0.748s][info][gc] GC(3) Pause Remark 101M->101M(172M) 0.580ms
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[0.749s][info][gc] GC(3) Pause Cleanup 101M->101M(172M) 0.018ms
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held=96MB heapUsed=101MB heapMax=2008MB freeHeap=70MB
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[0.751s][info][gc] GC(3) Concurrent Mark Cycle 19.274ms
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held=120MB heapUsed=126MB heapMax=2008MB freeHeap=45MB
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held=144MB heapUsed=151MB heapMax=2008MB freeHeap=45MB
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held=168MB heapUsed=176MB heapMax=2008MB freeHeap=45MB
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held=192MB heapUsed=201MB heapMax=2008MB freeHeap=45MB
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held=216MB heapUsed=226MB heapMax=2008MB freeHeap=45MB
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container exit code: 137
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