Monitoring memory usage for a C DLL called with Java via JNI?

Question

How can I monitor the memory being used by a native C DLL that is being called from Java via JNI? Using standard Java monitoring tools and options I can see the Java memory space, but I cannot view any memory used by the C DLL. Java is using ~70MB, but the task in the Task Manager shows 200Mb+, and I'd like to see what's in that 130MB extra if possible.

Answer 1

You can monitor the native heap with counters in the performance montitor. (perfmon32) however it wont break it down for you on a per DLL basis, even jvm.dll will be included here.

Most profiling tools out there can attach to a process and capture and track memory allocations and deallocations. This allows them to speculate where leaks are. One pretty good one i found when recently trying to track down memory leaks in native code which was called from Java is Memory Validator

Answer 2

Have you tried using Process Viewer to dig deeper.

If you have the source to the DLL you could rebuild with debug libraries and possibly a mem allocation tracker - and debug using visual C++ debugger (you'll need to tell it to use the java application).

If you haven't got the source - then the options are limited.