Re: Ever Increasing memory but not freed

UÄŸur ATA wrote:

> 1) I have tried getrusage() command and it didn't work for slackware
> 12.2 (Linux 2.6.27.7 kernel). It was returning zero no matter what and
> I read somewhere on the internet that it doesn't work for linux to get
> memory usage. That's why I wrote my own function.

Sorry, my mistake; on Linux, it only records CPU usage and page
faults, not memory. You can get equivalent information from
/proc/<pid>/{stat,statm,status}.

> 2) Yes, it is up to the kernel to release unused memory blocks on
> demand but what I am wondering is why the program crashes every time
> RSS reaches exactly the same amount which is almost 65MBs.

Coincidence? On an unloaded system, RSS will correlate closely with
virtual memory usage.

Is there an RSS limit (ulimit -m) in effect? If there is, the process
may start to swap when the limit is reached. If there are any
timing-related bugs, this could cause them to manifest.

> 3) My system has 1GB of free RAM and free memory exists every time a
> lot more than needed.
> 4) For some method calls RSS usage doesn't increase for subsequent
> calls but for some it increases every time. Otherwise it wouldn't be a
> problem if the memory usage stabilized on some level but it doesn't.

That tends to suggest a memory leak. Examining virtual memory usage
may help to confirm or deny this.

> 5) What is interesting is that in every method call RSS increases by
> 4K segments if it does. That made me think it is something related to
> the newly created stack in each method call.

4K is the x86 page size; any memory allocated by the kernel will be in
multiples of 4K.

-- 
Glynn Clements <[email protected]>
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