Garbage Collection every 100 seconds

Question

Did any one encountered a scenario where application under high memory allocation load performed second generation collection every 100 seconds ?

We using 64-bit server

Answer 1

You are probably generating more objects then can fit in the young heap all at once or you have a memory leak.

If you are intensively creating a lot of objects that need to be alive all at the same time, then you are probably overflowing the young section and some of the objects have to be copied to an older generation. This forces full collections more often as the older heap fills up. You probably need to find a way to allocate fewer objects in this case unless there is a way to request a larger young heap like there is with the Sun JVM.

If you actually store off the objects somewhere (say in a list owned by an old object), then you have a logical leak. In general, you don't want old objects referring to young ones. This tends to get the young objects promoted and the GC algorithms generally are optimized for it not happening. Also, you may want to considering clearing references if this significantly shortens the scope that an object can be alive in (although it usually is superfluous).

Barring that and you just have unusually high memory usage, there probably isn't a whole lot that you can do. Remember that for any long running program, you will eventually have to do some GCing, and the more memory you need at a time, the more often it comes.