On Mon, 23 May 2022 07:28:41 GMT, Yi Yang <yy...@openjdk.org> wrote: > It seems that calculation of > MemoryMXBean.getNonHeapMemoryUsage(jmm_GetMemoryUsage) is wrong. > > Currently, > `NonHeapUsage=CodeCache+Metaspace(ClassTypeSpace+NonClassTypeSpace)+CompressedClassSpace(ClassTypeSpace)` > > ==> CodeHeap 'non-nmethods' 1532544 (Used) > ==> CodeHeap 'profiled nmethods' 0 > ==> CodeHeap 'non-profiled nmethods' 13952 > ==> Metaspace 506696 > ==> Compressed Class Space 43312 > init = 7667712(7488K) used = 2096504(2047K) committed = 8454144(8256K) max = > -1(-1K) > > In this way, getNonHeapMemoryUsage is larger than it ought to be, it should > be `NonHeapUsage = CodeCache + Metaspace`.
The basic problem is that we have two non-heap pools: - `MetaspacePool` - consists of `ClassType` and `NonClassType` parts - `CompressedKlassSpacePool` but the `CompressedKlassSpacePool` is actually the "ClassType" part of the `MetaspacePool`! I think the right fix is to just convert the `MetaspacePool` into `NonClassMetaspacePool` and only report the non-class values. AFAICS this will only be visible via the MXBean. ------------- PR: https://git.openjdk.java.net/jdk/pull/8831
