[Twisted-web] Different behavior of twistd with and without -n

Terry Jones terry at jon.es
Thu May 24 19:52:51 EDT 2007

Hi Glyph

| The fork does some other things though, and it's hard to say which one is
| affecting the execution of your program, especially since PyLucene is doing
| a bunch of things at the machine-code level which are highly surprising to
| Python programmers.

I'm too old to be highly surprised any more, and I'm barely a Python
programmer... :-)

| Have you tried running 'strace' on this process yet?

No, I hadn't, thanks. Running ktrace sheds a little light on things. The
final output before it writes the core file is:

  7826 Python   CALL  write(0x2,0xbfff971f,0x18)
  7826 Python   GIO   fd 2 wrote 24 bytes
       "thread_get_state failed
  7826 Python   RET   write 24/0x18
  7826 Python   CALL  sigprocmask(0x3,0xbfff9b08,0)
  7826 Python   RET   sigprocmask 0
  7826 Python   CALL  kill(0x1e92,0x6)
  7826 Python   RET   kill 0
  7826 Python   PSIG  SIGABRT SIG_DFL
  7826 Python   NAMI  "/cores/core.7826"

Nothing fails before that.  The "thread_get_state failed\n" message does
not appear in the twisted server log. The kill is an abort to this process
(0x1e92 = 7826). So something (but not a system call) has gone wrong and
the code has called abort. That at least explains why the server abruptly

Running gdb python /cores/core.7826 and using where/bt provides no useful

  (gdb) where
  #0  0x00000000 in _mh_dylib_header ()

>From the kdump output, the process is clearly in the middle of doing
PyLucene things (there are a bunch of access calls to files that are in my
PyLucene index directories).

Grepping for 'thread_get_state failed' in Python, Twisted, and PyLucene
gets me just one hit:

  $ grep -i 'thread_get_state failed'  /usr/local/lib/*
  Binary file /usr/local/lib/libgcj.6.dylib matches

Which is a GCJ library file distributed with the Mac OS X binary version of
PyLucene. Google thread_get_state failed gives some leads.

I'll go bug the PyLucene folks now... :-)

Thanks again for the trace suggestion.


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