This is a bit vague, and I wanted to get some feedback before I submit a ticket. We have a long-running twisted / nevow process that basically has: root \- RPC2 - a twisted.web.xmlrpc.XMLRPC sub-class \- ui - nevow pages The thing hung up over the weekend with "too many open file descriptors" and before I killed it I did an "lsof"; lots of the files were: python25 20163 nsg 31u REG 253,0 370 3276854 /tmp/tmp5QJivu (deleted) ...and "cat /proc/20163/fd/31" shows: <?xml version='1.0'?> <methodCall> <methodName>classify_maclist</methodName> <params> <param> <value><string>HORPROD</string></value> </param> <param> <value><array><data> <value><string>xxxx</string></value> </data></array></value> </param> <param> <value><int>-1</int></value> </param> <param> <value><int>5</int></value> </param> </params> </methodCall> ...which is an XMLRPC call from a Zope server on another machine to this process. I presume the t.w.http.Request content is getting written to a tempfile, but I can't understand why - the Content-Length is tiny (<400 bytes). I can't seem to reproduce this in a sample application though; does anyone have any ideas how I can narrow down the problem?