Is it possible to instantiate a jvm from a heap dump?

Question

Everyone knows that a heap dump can be obtained from a running JVM. Is the other way possible? Can we start a JVM using a heap dump?

I have been having this question in mind for a long time now. If this is possible it would solve a lot of time and make thinks easy for a support engineer. It helps big time in cases where if we have to recreate some the rare problems our customer face. [Just imagine that the underlying hardware and Java runtime are the same and also all the supporting files are also present in the respective location in file system].

Added note: The intention of doing this is not when OOM occurs but at any given point after JVM starts.

Answer 1

No you can't. You would need things like the current position in each open file. That affects what data is returned on a simple sequential read. The restorer would need to open each file and get it to the correct position. That may not be possible for non-seekable streams.

Program specific serialization is a much more feasible path, then setup the program from there.

Also, as Heap Dumps are usually from OutOfMemory situtaions, recreating JVM from same would again throw OutOfMemoryException. If you are taking heap dump in between, then serialize your objects and restore them when you bring up jvm.

(contents copied from comments of this question, Authors almas-shaikh and patricia-shanahan)

Answer 2

To create a heap dump from a running JVM you can also use jhat, or jcmd (with the GC.heap_dump command), both exist in the JDK/bin folder. MAT is one way of analyzing the contents of the dump. Java Mission Control has a tool called JOverflow that analyzes heap dumps, but only to look at memory waste patterns.

I have never heard of any way to restart a JVM from sort of image, a heap dump would not be enough at all, since it only contains the Java objects, and not the compiled code and other things.