How to properly set the JVM options in a flexible GAE application

问题

the following is my app.yaml file for a GAE flexible Java 8 / Jetty application.

runtime: java
env: flex
manual_scaling:
  instances: 1

runtime_config:  # Optional
  jdk: openjdk8
  server: jetty9

resources:
  cpu: 2
  memory_gb: 4.0

env_variables:
  JAVA_HEAP_OPTS: -Xms3072M -Xmx3072M

health_check:
  enable_health_check: False

handlers:
- url: /.*
  script: this field is required, but ignored

For some reason the JAVA_HEAP_OPTS value is not used when deploying the app. A least I don't think it's used, because when I SSH into the docker container, and run the following command, the memory values are much less.

java -XX:+PrintFlagsFinal -version | grep -iE 'HeapSize|PermSize|ThreadStackSize'

Can someone please tell me what's going or what I need to do differently?

Thanks

回答1:

The variable is applied only to the Java process that runs as the entrypoint of the docker container.

JAVA_HEAP_OPTS is not a magic environment variable that would be automatically and globally applied to any random execution of Java inside the docker container. It is no wonder why you won't see any effect when you launch your own, separate Java process.

Take a look at the following code and you will understand how it works:

• https://github.com/GoogleCloudPlatform/openjdk-runtime/blob/9-2018-02-28_16_02/openjdk-common/src/main/docker/docker-entrypoint.bash#L32
• https://github.com/GoogleCloudPlatform/openjdk-runtime/blob/9-2018-02-28_16_02/openjdk-common/src/main/docker/setup-env.d/30-java-env.bash#L38

来源：https://stackoverflow.com/questions/49620058/how-to-properly-set-the-jvm-options-in-a-flexible-gae-application