CODEWITHSUNDEEP
javamemory-leaksgarbage-collectionprofilingvisualvm
barjak
barjak

Reputation: 11270

Which GC to use when profiling memory?

I use the NetBeans profiler (which is actually an embedded VisualVM) to monitor the memory consumption of my Java applications. I use the heap view, the surviving generation view, and memory dumps to track memory leaks.

The heap view shows the total of used memory, but it's a bit chaotic, due to the way the garbage collector manages the memory. The graph is essentially sawtooth-shaped, and thus not particularly readable. Sometimes, I force the GC to happen, so that I can have a more precise value of the real memory consumption.

I was wondering : is there a garbage collector which is more appropriate for memory profiling, and which would yield a heap graph closer to the real memory usage ? Or more generally, what JVM settings (-XX options or other) can I use in order to efficiently track memory leaks ?

example heap graph

Upvotes: 1

Views: 840

Answers (2)

Peter Lawrey
Peter Lawrey

Reputation: 533510

I suggest you use the GC you intend to use without the profiler. Using this approach you will get a graph which is more like how the application will behave, though not always as readable.

If you want a graph which is more readable, but not as realistic, you can increase the minimum memory size to say 1 GB. This will result in less GCs and a less spikey graph but may not help you except make the graph prettier.

Upvotes: 1

Amir Afghani
Amir Afghani

Reputation: 38531

What you are seeing in your graph is the real behavior of your applications memory utilization. The repeated sawtooth pattern is likely due to allocations of short lived objects which are being scavenged. If you believe you have a memory leak, take a heap dump snapshot and see what objects are being retained in the heap. You can take a snapshot using JConsole and open the resulting dumpfile using HPjmeter.

Upvotes: 4

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