Date: Fri, 20 Feb 2015 09:04:55 -0600 From: Matthew Grooms <mgrooms@shrew.net> To: freebsd-stable@freebsd.org Subject: Re: pthread leaky with resources? Message-ID: <54E74D17.6020209@shrew.net> In-Reply-To: <20150220100446.GL34251@kib.kiev.ua> References: <54E65E05.2040101@shrew.net> <20150220100446.GL34251@kib.kiev.ua>
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On 2/20/2015 4:04 AM, Konstantin Belousov wrote: > On Thu, Feb 19, 2015 at 04:04:53PM -0600, Matthew Grooms wrote: >> All, >> >> I have a multi-threaded program that runs on 10.1-RELEASE-p5. It starts >> out with a reasonable footprint but there is obviously a resource leak >> as the program uses substantially more memory over time ... >> >> PID USERNAME THR PRI NICE SIZE RES STATE C TIME WCPU COMMAND >> 51560 rdj 3 20 0 46676K 7500K select 1 0:00 0.00% dialyd >> >> ... 24h later ... >> >> PID USERNAME THR PRI NICE SIZE RES STATE C TIME WCPU COMMAND >> 51560 rdj 3 20 0 131M 27064K select 3 1:45 0.00% dialyd >> >> After a bit of debugging, I determined that it only happens when threads >> are created and then later destroyed. Valgrind thinks that the resources >> are being leaked from libthr itself ... > Threading library caches thread structures and some related objects. > This is needed to correctly handle kernel notifications about threads > exit and to avoid thread id reuse, besides usual argument for using cache > to improve creation speed. > > Also, the thread stacks are cached, each stack being 2MB probably accounts > for most of the memory usage columns in the top output above. Konstantin, Thanks for the reply. That seems reasonable. But surely these resources need to be reclaimed at some point after a thread gracefully exits. Otherwise any software that creates short lived threads will eventually run out of system resources and periodically require a restart. The test program I included does nothing but create threads that gracefully exit. Do you have another explanation as to why a program would indefinitely grow in size that way? Thanks, -Matthew
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