JVM heap dump path documentation is incorrect

[bittusarkar]

Elasticsearch version (bin/elasticsearch --version): Does not matter

Plugins installed: Does not matter

JVM version (java -version): 1.8

OS version (uname -a if on a Unix-like system): Windows 10

Description of the problem including expected versus actual behavior:
The documentation in https://www.elastic.co/guide/en/elasticsearch/reference/master/heap-dump-path.html says

If you specify a fixed filename instead of a directory, the JVM will repeatedly use the same file; this is one mechanism for preventing heap dumps from accumulating in the heap dump path.

This is not true. JVM fails to overwrite the heap file with following error (if say the JVM option -XX:HeapDumpPath=.\heapdump.hprof was used):

java.lang.OutOfMemoryError: Java heap space
Dumping heap to .\heapdump.hprof ...
Unable to create .\heapdump.hprof: File exists

As a result, only the first heap dump file will be created. No heap dump file will be created subsequently as the file would already exist. Can you please fix the documentation?

[jasontedor]

The documentation is indeed incorrect. The relevant JDK source is when the heap dump writer is constructed, a flag is explicitly passed to not overwrite an existing file. Thanks for catching this @bittusarkar, we will get the documentation corrected!

[elasticmachine]

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