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    <p>Check the <code>ulimit</code> and <code>quota</code> for the box and the user running the scripts. <code>/etc/security/limits.conf</code> may also contain resource restrictions that you might want to modify. </p> <p><code>ulimit -n</code> will show the max number of open file descriptors allowed.</p> <ul> <li>Might this have been exceeded with all of the open sockets?</li> <li>Is the script closing each sockets when it's done with it?</li> </ul> <p>You can also check the fd's with <code>ls -l /proc/[PID]/fd/</code> where <code>[PID]</code> is the process id of one of the scripts.</p> <p><em>Would need to see some code to tell what's really going on..</em></p> <hr> <p><strong>Edit</strong> (<em>Importing comments and more troubleshooting ideas</em>):</p> <p>Can you show the code where your <em>opening</em> and <em>closing</em> the connections?<br />When just run a few script processes are running, do they too start to go idle after a while? Or is it only when there are several hundred+ running at once that this happens?<br />Is there a single parent process that starts all of these scripts?</p> <p>If your using <code>s = urllib2.urlopen(someURL)</code>, make sure to <code>s.close()</code> when your done with it. Python can <em>often</em> close things down for you (like if your doing <code>x = urllib2.urlopen(someURL).read()</code>), but it will leave that to <strong>you</strong> if you if told to (such as assigning a variable to the return value of <code>.urlopen()</code>). Double check your opening and closing of urllib calls (or <em>all</em> I/O code to be safe). If each script is designed to only have 1 open socket at a time, and your <code>/proc/PID/fd</code> is showing multiple active/open sockets per script process, then there is definitely a <em>code</em> issue to fix.</p> <p><code>ulimit -n</code> showing <code>1024</code> is giving the <strong>limit</strong> of open <strong>socket/fd's</strong> that the <em>mysql</em> user can have, you can change this with <code>ulimit -S -n [LIMIT_#]</code> but check out this article first: <br /><a href="http://blogs.oracle.com/rainy/entry/changing_process_max_file_descriptor" rel="nofollow">Changing process.max-file-descriptor using 'ulimit -n' can cause MySQL to change table_open_cache value</a>.</p> <p>You may need to log out and shell back in after. And/Or add it to <code>/etc/bashrc</code> (don't forget to <code>source /etc/bashrc</code> if you change <code>bashrc</code> and don't want to log out/in).</p> <p><strong>Disk space</strong> is another thing that I have found out (the hard way) can cause very weird issues. I have had processes act like they are running (not zombied) but not doing what is expected because they had open handles to a log file on a partition with zero disk space left.</p> <p><code>netstat -anpTee | grep -i mysql</code> will also show if these sockets are connected/established/waiting to be closed/waiting on timeout/etc.</p> <p><strong><code>watch -n 0.1 'netstat -anpTee | grep -i mysql'</code></strong> to see the sockets open/close/change state/etc in <em>real time</em> in a nice table output (may need to <code>export GREP_OPTIONS=</code> first if you have it set to something like <code>--color=always</code>).</p> <p><code>lsof -u mysql</code> or <code>lsof -U</code> will also show you open FD's (the output is quite verbose).</p> <hr> <pre><code>import urllib2 import socket socket.settimeout(15) # or settimeout(0) for non-blocking: #In non-blocking mode (blocking is the default), if a recv() call # doesn’t find any data, or if a send() call can’t # immediately dispose of the data, # a error exception is raised. #...... try: s = urllib2.urlopen(some_url) # do stuff with s like s.read(), s.headers, etc.. except (HTTPError, etcError): # myLogger.exception("Error opening: %s!", some_url) finally: try: s.close() # del s - although, I don't know if deleting s will help things any. except: pass </code></pre> <hr> <p><strong>Some man pages and reference links:</strong></p> <blockquote> <ul> <li><a href="http://compute.cnr.berkeley.edu/cgi-bin/man-cgi?ulimit" rel="nofollow">ulimit</a></li> <li><a href="http://compute.cnr.berkeley.edu/cgi-bin/man-cgi?quota" rel="nofollow">quota</a></li> <li><a href="http://ss64.com/bash/limits.conf.html" rel="nofollow">limits.conf</a></li> <li><a href="http://en.wikipedia.org/wiki/Fork_bomb" rel="nofollow">fork bomb</a></li> <li><a href="http://blogs.oracle.com/rainy/entry/changing_process_max_file_descriptor" rel="nofollow">Changing process.max-file-descriptor using 'ulimit -n' can cause MySQL to change table_open_cache value</a></li> <li><a href="http://docs.python.org/library/socket.html" rel="nofollow">python <em>socket</em> module</a></li> <li><a href="http://linux.die.net/man/8/lsof" rel="nofollow">lsof</a></li> </ul> </blockquote>
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    1. COSorry should have mentioned - already when through this and allowed mysql user 16384 (soft and hard) connections via PAM - before I did this I could only start circa 1020 scripts as would be expected - now I can open '000s. However ulimit -n still does show 1024 - not sure if this makes a difference?
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    2. COAlso been googling Fork Bombs - but can't see that 1000 processes should have any issue especially as most of the time the scripts are spending time requesting data and with a 80MB (burst) connection would have thought this would be fine - will do some more investigation into quota - thanks.
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    3. COBoth quota -u mysql and quota -u root come back with nothing.
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