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montss
Asked: 2021-10-15 03:53:33 +0800 CST

容器环境中的Java大堆

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我正在尝试在 kubernetes 上运行一个 Jetty 网络服务器，它在我们的生产环境中需要大量的堆 ~ 250 GB，在我们的测试环境中 ~ 50 GB。

我正在使用jetty:9.4-jdk11，我试图避免显式设置Xms或Xmx标志，因为不同环境之间的值不同，因为我认为依赖-XX:MaxRAMPercentage -XX:InitialRAMPercentage会更好，但无论我尝试什么，我都无法MaxHeapSize通过32178700288 ~ 30 GB。

Node 上只有 Java 应用程序和一些小 sidcar，有 64 GB 内存。

Dockerfile

FROM jetty:9.4-jdk11

ENV APP_WAR root.war
ENV APP_EXPLODED_WAR root/
ENV APP_DESTINATION_PATH $JETTY_BASE/webapps/
ENV APP_DESTINATION_WAR $APP_DESTINATION_PATH$APP_WAR
ENV APP_DESTINATION_EXPLODED_WAR $APP_DESTINATION_PATH$APP_EXPLODED_WAR

ADD . $APP_DESTINATION_EXPLODED_WAR

ENV JAVA_OPTIONS -XX:+PrintFlagsFinal -XX:MaxRAMPercentage=90 -XX:InitialRAMPercentage=90 -XX:-OmitStackTraceInFastThrow -XX:+UseStringDeduplication -Xlog:gc*,stringdedup*=debug:file=/tmp/gc.log:time

容器资源设置

resources:
  limits:
    cpu: "8"
    memory: 60G
  requests:
    cpu: "6"
    memory: 60G

基于这些值，我应该得到 60 GB MaxHeapSize~ 54 GB 的 90%，而不是 30 GB。知道我缺少什么吗？

java jetty kubernetes google-kubernetes-engine containers

1 个回答

  1. Best Answer

    -XX:+UseCompressedOopsJava 11 上默认启用的JVM 参数是原因，来自文档。

    -XX:-UseCompressedOops
    
Disables the use of compressed pointers. By default, this option is enabled, and compressed pointers are used when Java heap sizes are less than 32 GB. When this option is enabled, object references are represented as 32-bit offsets instead of 64-bit pointers, which typically increases performance when running the application with Java heap sizes of less than 32 GB. This option works only for 64-bit JVMs.
    
It’s also possible to use compressed pointers when Java heap sizes are greater than 32 GB. See the -XX:ObjectAlignmentInBytes option.

    只需更改-XX:+为-XX:-如上所示将禁用它。

    -XX:ObjectAlignmentInBytes在我的情况下也不建议使用相同的文档。

    -XX:ObjectAlignmentInBytes=alignment

Sets the memory alignment of Java objects (in bytes). By default, the value is set to 8 bytes. The specified value should be a power of 2, and must be within the range of 8 and 256 (inclusive). This option makes it possible to use compressed pointers with large Java heap sizes.

The heap size limit in bytes is calculated as:

4GB * ObjectAlignmentInBytes

Note:

As the alignment value increases, the unused space between objects also increases. As a result, you may not realize any benefits from using compressed pointers with large Java heap sizes.

    但我想它值得测试。

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