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Showing posts from September, 2018

JVM container profiling from a container

In an earlier blog post, I talked about flame graphs and how I implemented those for a Scala app. Ever since I have been thinking if it would be possible to grab a flame graph from a container. Some time ago I made that happen inspired by this post.  It was not enough for me, I wanted to go deeper. I wanted also the profiler to run inside a container profiling another container. So I ended up making this It uses the JVM  async-profiler tool so not quite the same that in my previous blog post but the results are similar. To profile another container, you can use the one-liner and replace the $CONTAINER_ID with the id of the running JVM container you want to profile, $PERF_IMAGE as the built image id of the described container and  $JAVA_PID with the, you guessed it, the JVM pid inside the subject container. You also need to set a couple of runtime variables on the docker host as described in the async-profiler setup instructions. There are a couple of drawbacks. Firstly you n