Problem: sometimes select() doesn't return. Context: I run a DB replication scenario, with cron, everything 5 mn. There is no change in the DB, so the scenario is always the same. Most of the time, it works. But eventually, after some time (may be some minutes or hours), a process A keeps waiting forever in select() for a response on a TCP socket. With gdb I can see that the other end B returned in its ReadCommand() function, meaning it has send its response and waits for a new command, so this side should be OK.
Here is the stack for A : (gdb) bt #0 0x77f682cb in ntdll!ZwWaitForMultipleObjects () from /cygdrive/c/WINNT/System32/NTDLL.DLL #1 0x77f1ce6b in WaitForMultipleObjectsEx () from /cygdrive/c/WINNT/system32/KERNEL32.DLL #2 0x77f1cd76 in WaitForMultipleObjects () from /cygdrive/c/WINNT/system32/KERNEL32.DLL #3 0x61073703 in sigpending () from /usr/bin/cygwin1.dll #4 0x61069de2 in select () from /usr/bin/cygwin1.dll #5 0x002145e0 in ?? () By adding many printf traces, the problem appears more quickly, so I can reproduce it very easily. Just one run of cron is enough. (file descriptors are more solicited...?) I know that I'm not providing much info to reproduce the problem. But my environment is not so simple: it involves: cron -> sh -> pgtclsh (TCL interpretor of Postgresql) -> a cnx is made with a Postgresql backend It seems that the last command executed by Postgresql in the replication scenario is a "copy <table> to <file>", which creates more file descriptors. May be a clue. I was initially in version 1.5.5-1. Searching the archives, I saw http://sources.redhat.com/ml/cygwin/2003-11/msg00137.html http://sources.redhat.com/ml/cygwin/2003-10/msg01812.html reporting some problems with select() in 1.5.5-1. My first reaction was to upgrade to 1.5.7-1, hoping the problem would be solved. :( no. These reports were more related to UDP or pipes, not TCP sockets. But the symptoms are similar. Is it possible that a correction of the same kind as the one for the pipes is applicable in this case? Feel free to ask me for more investigation, I'm willing to help. Just tell me how. Patrick __________________________________ Do you Yahoo!? Yahoo! Finance: Get your refund fast by filing online. http://taxes.yahoo.com/filing.html
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