Question: What is the Difference Between Core Dump and Heap Dump?
Answer: Heap dump – Collection of objects that are in memory (JVM)
Thread dump – Shows what each thread in a process is doing at a given point in time along with the stack trace.
Core dump – O/S level dump file which has O/S level info in addition to the heap dump.
Heap dump – is useful to analyze OOM situations.
Thread dump – To troubleshoot the slow running of your application. (E learning Portal)
Core dump – When your JVM has crashed abruptly. To find details about native calls and so on.
Core dump will be generated automatically if a program crashed due to segmentation fault or some other reason. But core dump will not be generated if an application halt and been terminate by control+c or conventional way of kill or kill.
To force a core dump generation, you could run kill -6
You should also make sure that you have enabled it and have provided enough space and permissions for it to get generated.
For Linux, the core-dump is turned off by default on all systems. For RedHat Advanced Server 2.1, it should be under /etc/security. There should be a self-explanatory file called limits.conf and look for the word “core”. If set to “0”, then the core-dump is disabled.
For Solaris, you can also make sure core files are enabled with the cream command.
Check ulimit -a to see whether your environment allows core files to be produced.
ulimit -c (This is the size limit of the core file. Fix it with ulimit -c unlimited).
Kernel limitation (the hard limit for ulimit -c).
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