From: Charles Forsyth <charles.forsyth@gmail.com>
To: Fans of the OS Plan 9 from Bell Labs <9fans@9fans.net>
Subject: Re: [9fans] file descriptor leak
Date: Tue, 16 Feb 2016 22:24:08 +0000 [thread overview]
Message-ID: <CAOw7k5jtphVPgXd-ao=Dp6-TWoMC4mxxnTdY0upKJWq_ATxgrw@mail.gmail.com> (raw)
In-Reply-To: <8FB7CBFD-7334-4F9F-8C71-571DEF9FAD31@ar.aichi-u.ac.jp>
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On 16 February 2016 at 15:52, arisawa <arisawa@ar.aichi-u.ac.jp> wrote:
>
> I have observed warning messages from dns server:
> dns 30792: warning process exceeded 100 file descriptors
> dns 30888: warning process exceeded 200 file descriptors
>
It's worth noting that this message doesn't necessarily mean you've got a
file descriptor leak.
It might, but at the start it just means that a process (or process group
sharing a file descriptor group) has many file descriptors open.
That could happen if a server with many clients has a file descriptor per
client and then client requests open some more.
ndb/dns in particular will try user-level requests in parallel, and those
in turn can lead to several concurrent
queries to various name servers at a given level (root itself has 13). Web
browser clients will fetch page
elements concurrently. That's why it's useful to check the /proc/N/fd file
to try to see what they are.
(Not just for ndb/dns, but for other applications that provoke the message.)
Arguably, if you're using the system in a real, Internet-facing
application, the warning message might
be obsolete, compared to the time when even 100 clients was a big network.
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next prev parent reply other threads:[~2016-02-16 22:24 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-02-16 15:52 arisawa
2016-02-16 15:56 ` Jacob Todd
2016-02-16 16:42 ` lucio
2016-02-16 17:05 ` Jacob Todd
2016-02-16 17:17 ` Charles Forsyth
2016-02-16 18:01 ` cinap_lenrek
2016-02-16 21:05 ` erik quanstrom
2016-02-16 21:16 ` Charles Forsyth
2016-02-17 2:19 ` cinap_lenrek
2016-02-22 5:18 ` erik quanstrom
2016-02-16 22:24 ` Charles Forsyth [this message]
2016-02-17 1:13 ` arisawa
2016-02-17 1:22 ` cinap_lenrek
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