On 02/06/2017 01:51 PM, Yann Ylavic wrote: > On Mon, Feb 6, 2017 at 1:42 PM, Yann Ylavic <ylavic....@gmail.com> wrote: >> On Mon, Feb 6, 2017 at 1:29 PM, Ruediger Pluem <rpl...@apache.org> wrote: >>> >>> >>> On 02/06/2017 11:56 AM, Yann Ylavic wrote: >>>> Hi Stefan, >>>> >>>> On Mon, Feb 6, 2017 at 9:57 AM, Stefan Priebe - Profihost AG >>>> <s.pri...@profihost.ag> wrote: >>>>> >>>>> your last patch results in multiple crashes every second: >>>> >>>> Sorry about that, the changes in mpm_event were incorrect (the mutex >>>> was cleared with the pool when recycled, hence its pointer was >>>> dangling). >>>> >>>> New patch attached, this time tested with the httpd framework (where >>>> the previous patch segfaulted too). >>>> >>>> Thanks, >>>> Yann. >>>> >>> >>> Hmm, does it make sense performance wise to create the mutex over and over >>> again? >>> Or is this planned to be improved once it is known to fix the crash issue? >> >> Yes, I'm thinking of it, but it's not easy because we need a pool to >> create the mutex. >> Using ptrans makes it cleared on recycle (hence re-created), and using >> the parent pool (pconf) requires synchronization. >> >> Possibly we could recycle both the pool (or the allocator) and its >> mutex, but ap_push/pop_pool() wouldn't be lockless anymore... > > Not sure it's really worth it either because apr_thread_mutex_create() > should boil down to "*mutex = PTHREAD_MUTEXT_INIT" on *nix, and > probably something equivalent for InitializeCriticalSection() on > windows... > We probably not spend many cycles here (compared to more synchronization).
The question how much cycles this spends in GLIBC / kernel. I don't know. So maybe its not worth the effort. But if its not worth the effort it is worth documenting why :-) Regards Rüdiger
