chetanmeh commented on issue #74: Dynamically setting the JVM memory limit by reading the Cgroup URL: https://github.com/apache/openwhisk-runtime-java/pull/74#issuecomment-524178152 @mrutkows Currently the java runtime uses openj9 instead of openjdk https://github.com/apache/openwhisk-runtime-java/blob/a8e666f7b38d533192fce897342037f4ca570a41/core/java8/Dockerfile#L18 Open J9 does not support `-XX:+UseCGroupMemoryLimitForHeap` and instead has a different flag [UseContainerSupport][1]. This flag is enabled by default in Docker base images we use in OpenWhisk ``` $ docker run --rm -m 1g openwhisk/java8action /bin/bash -c 'echo $JAVA_TOOL_OPTIONS' -XX:+IgnoreUnrecognizedVMOptions -XX:+UseContainerSupport -XX:+IdleTuningCompactOnIdle -XX:+IdleTuningGcOnIdle ``` See also [this blog post][2]. Also j9 does not support `-XX:+PrintFlagsFinal` instead provides [few different flags to get the defaults][3] So I believe we are good here and do not need to explicitly specify memory settings for build version we are using [1]: https://www.eclipse.org/openj9/docs/xxusecontainersupport/ [2]: https://royvanrijn.com/blog/2018/05/java-and-docker-memory-limits/#test-6-openj9-nightly [3]: https://github.com/eclipse/openj9/issues/527#issuecomment-497003442
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