VisualVM in production?

Question

I consider running VisualVM against a production JVM to see what's going on there - it started to consume too much CPU for some reason.

It must not result in a JVM failure so I'm trying to estimate all the risks.

The only issue that I see on their site that could potentially bring JVM down is related to class sharing and -Xshare JVM option, but afaik class sharing is not enabled in server mode and/or on x64 systems.

So is it really safe to run VisualVM against a production JVM, if it's not - what are the risks that one should consider, and how much load (CPU/memory) does running VisualVM against a JVM (and profiling with it) put on it?

Thanks

Answer 1

AFAIK VisualVM can be used in production, but I would only use it on a server which is lightly loaded. What you could do is wait for the service to slow down and later when its not used as much test it to see if some of the collections are surprising large. Or you could trigger a heap dump and analyze it offline.

And you can't get stats on method calls without significant overhead. Java 6 and 7 are better than java 5 but it could still slow your application by 30% even wityh a commercial profiler.