How to take a heap dump in windows with minimum downtime?
After you've taken the coredump by WinDbg, you need to extract the heap dump from it by running
jmap -heap:format=b "C:\Program Files\Java\...\bin\java.exe" core.mdmpThis could be done offline; no interaction with running Java process needed. Then you will be able to open the generated heap.bin in VisualVM.
Alternatively you may take the class histogram. It is produced a way faster than full heap dump.
jmap -histo <PID>It shows you the list of classes whose instances occupy the most space in the heap. This information is often enough to get the idea of where's the memory lost.