[collectd] [PATCH 0/2] Memory leak in unixsocket plugin

[Peter Warasin]

Hi,

after upgrading to 4.9.1 i still see the collectd process growing.
We are heaviliy using the LISTVAL/GETVAL commands throught the unixsocket
plugin, which makes the process grow to about 180M a day.

After analyzing a bit, I found a more or less obvious memory leak, which
happens always when writing to the socket fails. In that case,
print_to_socket() returns(-1) without freeing the memory.

We have many failures writing to the socket, probably because it is
an ajax tool polling constantly.

I attached 2 patches against 4.9.1, which fixes this leak. The first patch
is an implementation of a simple garbage collector (seen in openvpn code)
and the second replaces the sfree()'s with the garbage collector cleanup and
triggers cleanup on return.

I will stress-test this now for a while. Probably also using dmalloc,
since I fear there's still another memory leak.

At least when I tried to constantly FLUSH, the process is still growing
fast. LISTVAL and GETVAL *seem* to be ok now, since under listval/getval
hammering the process size keeps constant for most of the time. After a while
it grows a little.. That's probably because of the flush leak.


Comments on this patchset are much appreciated.

BTW: changing the garbage collector in a manner like openvpn does (take a
look at it), would reduce the risk of a memory leak greatly. 
It's however necessary to wrap *all* memory allocations in order to make it
in a sane manner.


Ok,. working on flush now..

Kind regards,
peter

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