Wednesday, March 28, 2018

ADF on Docker - Java Memory Limit Tuning for JVM

It might look like a challenge to run Java in Docker environment, by default Java is not aware of Docker memory limits. Check this article for example - Java inside docker: What you must know to not FAIL.  I was able to run WebLogic and ADF (Essential WebLogic Tuning to Run on Docker and Avoid OOM) on Docker previously without Java memory issues, using JAVA_OPTIONS=-XX:+UnlockCommercialFeatures -XX:+ResourceManagement -XX:+UseG1GC. However after Docker upgrade to latest version, these settings didn't help anymore. I did't want to hardcode memory setting with -Xmx.

Java started to consume all available memory in Docker and eventually was killed. You can see this from chart below - memory is growing, killed and after restart growing again:


To solve this behaviour, I have applied settings from Java Platform Group, Product Management Blog - Java SE support for Docker CPU and memory limits. I have replaced JAVA_OPTIONS=-XX:+UnlockCommercialFeatures -XX:+ResourceManagement -XX:+UseG1GC set previously with JAVA_OPTIONS=-XX:+UnlockExperimentalVMOptions -XX:+UseCGroupMemoryLimitForHeap -XX:+UseG1GC.

JAVA_OPTIONS=-XX:+UnlockExperimentalVMOptions - XX:+UseCGroupMemoryLimitForHeap -XX:+UseG1GC did the job - JVM stays in Docker memory limits sharp:


This chart shows Java memory behaviour before and after settings were applied. From March 27th - Java memory is a straight line with JAVA_OPTIONS=-XX:+UnlockExperimentalVMOptions - XX:+UseCGroupMemoryLimitForHeap -XX:+UseG1GC:

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