Hello Michal,

2012/3/5 Michal Trojnara <Michal.Trojnara@mirt.net>

I am using fork mode because of leaks with pthread. In 4.33+pthread,
stunnel virt size (per top) went up to 216m after 40k transactions. In
fork mode, stunnel size after the same test was 20744 (kilobytes). In
4.45, I have 187m and 20676k respectively.

I observed the same symptoms. Stunnel grows to ~200MB of virtual memory after some time of usage. Then it stops growing further. I guess this issue is caused by heap fragmentation rather than a memory leak. Otherwise the growth would not be limited to ~200MB.
https://en.wikipedia.org/wiki/C_dynamic_memory_allocation

I ran a test overnight that confirmed your point. I generated 480k+ stunnel transactions. This morning, stunnel memory usage is virt=187m and res=42m. My result after 40k transactions was exactly the same (in both cases with pthread+zlib).

I understand that virt includes shared libs, and that any issue with a
shared lib will impact virt size. I did not have the opportunity to test
without zlib support in openssl. Since we are not using compression, I
wonder how much avoiding zlib would help.

zlib only uses lots of memory when it's enabled.

I ran another test to clarify this. zlib appears to be adding around 3 megabytes at most. This is at least what I see under my setup and type of usage.

pthread+zlib, 40k transactions
before: virt=20680, res=792
after: virt=187m, res=42m

pthread+nozlib, 40k transactions
before: virt=20688, res=896
after: virt=185m, res=39m

I have seen no benefit of compiling without zlib in fork mode. I guess it only makes forking a bit lighter.