rsync - Oct 2010 - DO NOT REPLY [Bug 7749] New: socket listen queue fills, rejects further connections

https://bugzilla.samba.org/show_bug.cgi?id=7749

           Summary: socket listen queue fills, rejects further connections
           Product: rsync
           Version: 2.6.9
          Platform: x86
        OS/Version: Linux
            Status: NEW
          Severity: normal
          Priority: P3
         Component: core
        AssignedTo: wayned at samba.org
        ReportedBy: rhalsell at wikimedia.org
         QAContact: rsync-qa at samba.org


We have run into an issue where the rsync daemon socket listen queue (accept
queue) is filling before it is able to accept() the incoming connection
requests.  It appears that the rsync source code currently hard codes this
limit to 5.

On our deployment, we push our changes via dsh and sync to hundreds of servers
for Wikipedia in as fast a manner as possible.  This is causing the systems to
back up in the listen backlog and failing multiple servers as they eventually
time out, being ignored by the rsync server in question.  The socket.c source
shows this hard limit (presently set to 5).  We were able to fix the bottleneck
by raising the hard-coded value to 255.  We would propose that this be changed
to a configuration variable, which can default to the old value of 5.


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https://bugzilla.samba.org/show_bug.cgi?id=7749


wayned at samba.org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|ASSIGNED                    |RESOLVED
         Resolution|                            |FIXED
            Version|2.6.9                       |3.1.0




------- Comment #1 from wayned at samba.org  2011-01-03 21:44 CST -------
I have added the "listen backlog" global daemon parameter to the
rsyncd.conf
file (defaults to 5).

Something else you can try is to use xinetd as the listener that spawns rsyncd
instances instead of having rsync --daemon do that.


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