From: Eric Wong <email@example.com> To: "Lin Jen-Shin (godfat)" <firstname.lastname@example.org> Cc: email@example.com, firstname.lastname@example.org Subject: Re: What would happen if a worker thread died? Date: Fri, 8 May 2015 17:03:11 +0000 [thread overview] Message-ID: <20150508170311.GA1260@dcvr.yhbt.net> (raw) In-Reply-To: <CAA2_N1umJO12XH9r+JHnA6r=z=Mwp_PqOrdnW65oqW2K2-iAoQ@mail.gmail.com> "Lin Jen-Shin (godfat)" <email@example.com> wrote: > During the experiments, we found that whenever a worker > thread died due to LoadError raised from the application, > which is not a StandardError therefore was not rescued at all, > crashing the worker thread (assumed, not verified). Ugh, I guess since it happened in a thread, the error message got swallowed unless you were running in $DEBUG. Loading code after the server is ready and serving requests is a bad idea. It leads to really nasty thread-safety problems as well as invalidating the method/constant caches. > When this happened, the client just hanged forever with yahns. > Is there something we can do about this? Would yahns respawn > a new worker thread? Can we close the socket when this happen? It's unfortunately difficult to detect thread death from ruby (no SIGCHLD handler unlike for processes) besides polling Thread#join We had this issue in ruby-core a few years back, but apparently it was forgotten/ignored by matz. Care to chime in? https://bugs.ruby-lang.org/issues/6647 > I am aware that yahns is *extremely sensitive to fatal bugs in the > applications it hosts*, so I am just curious. > > For reference, Puma would immediately close the socket without > sending anything, and Unicorn would log the error backtrace and > kill the worker (If I read it correctly). > > In this case, Unicorn helped me figure out what's happened. yahns can probably rescue Exception (or Object(!) like puma) and then log + abort the entire process.
next prev parent reply other threads:[~2015-05-08 17:03 UTC|newest] Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top 2015-05-08 12:20 Lin Jen-Shin (godfat) 2015-05-08 17:03 ` Eric Wong [this message] 2015-05-08 17:36 ` Lin Jen-Shin (godfat) 2015-05-09 1:03 ` Eric Wong 2015-05-09 7:26 ` Lin Jen-Shin (godfat) 2015-05-09 8:47 ` Eric Wong 2015-05-09 9:03 ` [PATCH] worker threads log LoadError and SyntaxError, too Eric Wong 2015-05-09 9:06 ` What would happen if a worker thread died? Lin Jen-Shin (godfat)
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