I have some frequent full GC problems in production with Java, I suspect the memory was allocated by network library for buffering TCP request result.
I have dump the Java heap when the memory usage is high (about 8GB). I tried to analyze the .HPROF file with eclipse MAT, the file is about 8GB.
But in eclipse MAT, the total heap size is about 200 MB, so I could not find which objects are taking up to 8GB heap memory.
Since eclipse MAT is not showing the full heap dump content, I don't know how to find why the application is taking so much memory.
If you are using MAT memory analyzer to open the hprof dump, it may be that the rest of the heap are unreachable objects, which MAT hides by default, see https://stackoverflow.com/a/20405267/3484881