Does the size of the core file reflects the memory usage when the application crashed?

Question

My application(C++ on Sol 10 - 32 bit) crashed, and the size of the core generated by the application is 4 GB. Can I assume the application may use memory up to 4 GB (same as the size of the core file) when it is about to crash? PS. My application is standalone and doesn't depend on any other processes.

Is there any way to check the total memory the application used, with the core file?

Answer 1

Yes, the core file represent a dump of the whole virtual memory area used by the process when the crash happened. You can't have more than a 4 GB core file with 32 bit processes.

Under Solaris, you can use several commands located in /usr/proc/bin to get information from the core file. In particular:

• file core : will confirm the core file is from your process
• pstack core : will tell you where the process crashed
• pmap core : will show you memory usage per address

You can limit the set of data saved in a core file, among other things, by using the coreadm command. By default everything is saved:
stack + heap + shm + ism + dism + text + data + rodata + anon + shanon + ctf

Answer 2

From the manpage (http://linux.die.net/man/5/core):

The default action of certain signals is to cause a process to terminate and produce a core dump file, a disk file containing an image of the process's memory at the time of termination.

Possibly your code is using a multi-threaded environment and shared data.

Also:

Since kernel 2.6.23, the Linux-specific /proc/PID/coredump_filter file can be used to control which memory segments are written to the core dump file in the event that a core dump is performed for the process with the corresponding process ID.

Possibly through this you can get to know the memory used by the application.