From: Cedric Maion <cedric@maion.com>
To: Eric Wong <normalperson@yhbt.net>
Cc: unicorn list <mongrel-unicorn@rubyforge.org>
Subject: Re: [PATCH] `kill -SIGTRAP <worker pid>`
Date: Sun, 24 Jun 2012 13:05:53 +0200 [thread overview]
Message-ID: <4FE6F491.6070108@maion.com> (raw)
In-Reply-To: <20120623185534.GA17517@dcvr.yhbt.net>
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Hi,
> Please keep Subject lines a reasonable length (git recommends the commit
> message subject wrap at ~50 columns or so) and wrap code at <= 80
> columns
ok
> SIGKILL timeout is only a last line of defense when the Ruby VM itself
> is completely broken. Handling SIGTRAP implies the worker can still
> respond (and /can/ be rescued), so your SIGTRAP handler is worthless if
> SIGKILL is required to kill a process.
Sure. But if the VM is responding, being able to get a backtrace is nice.
And if it's stuck, you won't get anything indeed, but that's still an
information (in that case, one may eventually want to get a gdb
backtrace too). No?
> See http://unicorn.bogomips.org/Application_Timeouts.html
Yes, I'm well aware of this. However, when you still get rare unicorn
timeouts, debugging them is not obvious.
In my case, a server in a loadbalanced farm sometimes sees all it's
unicorn workers timeout in the same minute (approx once a day at what
seems a random time) -- other servers are fine. Couldn't correlate this
with any specific network/disk/misc system/user activity yet.
> Sleeping here is also unacceptable since it blocks the main loop,
> making masters signal handlers non-responsive for too long.
ok.
>
> Using the Logger class inside a signal handler can deadlock. Logger
> attempts to acquire a non-reentrant lock when called. Unicorn doesn't
> use threads itself, but the Rack app may use threads internally.
ok, can be replaced with a $stdout.write then.
> Thanks for your interest in unicorn!
Thanks for your feedback,
Kind regards,
Cedric
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next prev parent reply other threads:[~2012-06-24 11:07 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-06-23 16:12 `kill -SIGTRAP <worker pid>` to get a live ruby backtrace + generate backtrace when murdering worker due to timeout Cedric Maion
2012-06-23 16:12 ` [PATCH] `kill -SIGTRAP <worker pid>` to get a live ruby backtrace + generate backtrace when murdered " Cedric Maion
2012-06-23 18:55 ` [PATCH] `kill -SIGTRAP <worker pid>` Eric Wong
2012-06-24 11:05 ` Cedric Maion [this message]
2012-06-25 3:59 ` Eric Wong
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