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<TITLE>RE: [Beowulf] Concurrently open sockets limit on Linux system</TITLE>
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<P><FONT SIZE=2>Mark -- more good thoughts!</FONT>
</P>
<P><FONT SIZE=2>Ulimit doesn't seem to be an issue here, and the darn thing is definitely only holding open one connection per client (according to lsof, that is).</FONT></P>
<P><FONT SIZE=2>Interestingly, /proc/sys/fs/file-nr reports something odd:</FONT>
<BR> <FONT SIZE=2>cat /proc/sys/fs/file-nr</FONT>
<BR> <FONT SIZE=2>1605 0 65535</FONT>
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<P><FONT SIZE=2>This suggests that there are 0 free allocated file descriptors. I'm not clear on the implications here. I can certainly continue to open files on this box, and make new remote connections via ssh...</FONT></P>
<P><FONT SIZE=2>Simon</FONT>
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<P><FONT SIZE=2>-----Original Message-----</FONT>
<BR><FONT SIZE=2>From: Mark Hahn [<A HREF="mailto:hahn@mcmaster.ca">mailto:hahn@mcmaster.ca</A>]</FONT>
<BR><FONT SIZE=2>Sent: 2007 Jun 17 3:20 PM</FONT>
<BR><FONT SIZE=2>To: Galton, Simon</FONT>
<BR><FONT SIZE=2>Cc: 'beowulf@beowulf.org'</FONT>
<BR><FONT SIZE=2>Subject: Re: [Beowulf] Concurrently open sockets limit on Linux system</FONT>
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<P><FONT SIZE=2>> The vendor feels that they have not coded a specific limit; I'm wondering if</FONT>
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<P><FONT SIZE=2>in cases like this, I tend to do things like replace the license</FONT>
<BR><FONT SIZE=2>manager by a script that first does "ulimit -a" before execing </FONT>
<BR><FONT SIZE=2>the actual program. if the license manager is being execed through</FONT>
<BR><FONT SIZE=2>su to run unprivileged, for instance, it's not always obvious whether</FONT>
<BR><FONT SIZE=2>some ulimit is in effect. similarly, I often cut to the chase and </FONT>
<BR><FONT SIZE=2>run such a daemon under strace, to see what it's doing that fails.</FONT>
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<P><FONT SIZE=2>128-clients is such a low number that it doesn't sound like something</FONT>
<BR><FONT SIZE=2>more exotic like an ephemeral-port-range limit. 128 is remarkably low,</FONT>
<BR><FONT SIZE=2>though - you'd expect a multi-connection daemon might burn one fd </FONT>
<BR><FONT SIZE=2>per connection, but even a very desktop-y setting of NOFILE to 1024</FONT>
<BR><FONT SIZE=2>would imply that the daemon is keeping ~8 fd's open per connection.</FONT>
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<P><FONT SIZE=2>> it's file descriptors or somesuch. I raised the limit of FDs on the system</FONT>
<BR><FONT SIZE=2>> to 65000+ and verified that the change took effect; no change to the</FONT>
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<P><FONT SIZE=2>the system-wide (/proc/sys) setting is not likely to be the issue.</FONT>
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<P><FONT SIZE=2>> CONFIDENTIAL AND PRIVILEGED INFORMATION NOTICE</FONT>
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<P><FONT SIZE=2>are you aware that this nonsense has _no_ legal standing?</FONT>
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<P><FONT SIZE=2>regards, mark hahn.</FONT>
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