From: Eric Wong <normalperson@yhbt.net>
To: unicorn list <mongrel-unicorn@rubyforge.org>
Subject: Re: pid file handling issue
Date: Thu, 24 Oct 2013 00:53:17 +0000 [thread overview]
Message-ID: <20131024005316.GA10239@dcvr.yhbt.net> (raw)
In-Reply-To: <CABHxtY4KFQ5SXSsWqxUVu5MfiGBELOxQa2fT2-hGidx8Zbyuow@mail.gmail.com>
Michael Fischer <mfischer@zendesk.com> wrote:
> Hi everyone,
>
> While writing a script to determine the success or failure of a
> Unicorn reload attempt (without having to parse a log), I noticed that
> Unicorn doesn't preserve the timestamp of its pid file. In other
> words, instead of renaming pidfile to pidfile.oldbin (and then back
> again if the reload failed), it creates a new pid file for each master
> phase change.
>
> This means we cannot simply compare the mtime of the current pidfile
> against the time the USR2 signal was given in order to make a
> reasonable conclusion.
>
> I tried another method, which was to look at the start time of the
> process as reported by ps(1), but on Linux, that time does not come
> from the wall clock: it's derived from the number of jiffies since
> system boot. So it's not guaranteed to be accurate, especially if the
> wall clock was incorrect at system boot.
>
> Are there any other methods anyone can suggest? Otherwise, a change
> to Unicorn's behavior with respect to pid file maintenance would be
> kindly appreciated.
I read and stash the value of the pid file before issuing any USR2.
Later, you can issue "kill -0 $old_pid" after sending SIGQUIT
to ensure it's dead.
Checking the mtime of the pidfile is really bizarre...
OTOH, there's times when users accidentally remove a pid
file and regenerate by hand it from ps(1), too...
_______________________________________________
Unicorn mailing list - mongrel-unicorn@rubyforge.org
http://rubyforge.org/mailman/listinfo/mongrel-unicorn
Do not quote signatures (like this one) or top post when replying
next prev parent reply other threads:[~2013-10-24 0:53 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-10-23 22:55 pid file handling issue Michael Fischer
2013-10-24 0:53 ` Eric Wong [this message]
2013-10-24 1:01 ` Michael Fischer
2013-10-24 2:03 ` Eric Wong
2013-10-24 17:51 ` Michael Fischer
2013-10-24 18:21 ` Eric Wong
2013-10-24 19:57 ` Michael Fischer
2013-10-24 20:27 ` Eric Wong
2013-10-24 22:58 ` Eric Wong
2013-10-25 7:33 ` Hongli Lai
2013-10-25 20:31 ` Eric Wong
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
List information: https://yhbt.net/unicorn/
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20131024005316.GA10239@dcvr.yhbt.net \
--to=normalperson@yhbt.net \
--cc=mongrel-unicorn@rubyforge.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
Code repositories for project(s) associated with this public inbox
https://yhbt.net/unicorn.git/
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for read-only IMAP folder(s) and NNTP newsgroup(s).