Re: cx_Oracle messes up signals

‎This is not cx_Oracle - it is the Oracle client libraries.


Gaius




From: CRV§ADER//KY
Sent: Wednesday, 6 August 2014 12:35
To: cx-oracle-users-5NWGOfrQmneRv+LV9MX5uipxlwaOVQ5f@public.gmane.org
Reply To: cx-oracle-users-5NWGOfrQmneRv+LV9MX5uipxlwaOVQ5f@public.gmane.org
Subject: [cx-oracle-users] cx_Oracle messes up signals


Hi all,
     I'm using cx_Oracle 5.1.2 on Python 2.6 on Linux.

I found out that cx_Oracles interferes heavily with signal handling.
This is BAD, because it causes mysterious failures later on in the
code. It personally took me A LOT of time to figure what the heck was
going on.

Expected behaviour would be for cx_Oracle to respect whatever signal
handling is used in the code invoking the library. If you _really_
need to touch signals, that should be done in a subprocess.

Thanks


proof-of-concept code:

#!/usr/bin/env python

import cx_Oracle
import subprocess
import signal
import time
import os
from threading import Thread

def signalme():
    time.sleep(2)
    os.kill(os.getpid(), signal.SIGWINCH)

# Completely ignore SIGWINCH
signal.signal(signal.SIGWINCH, signal.SIG_IGN)
signal.siginterrupt(signal.
SIGWINCH, False)

print "do a syscall"
Thread(target=signalme).start()
subprocess.check_call("sleep 5", shell=True)

print "run oracle"
connection = cx_Oracle.connect('myuser', 'mypass', 'mytns')
connection.close()

print "do a syscall"
Thread(target=signalme).start()
subprocess.check_call("sleep 5", shell=True)

print "all done!"



Output:
do a syscall
run oracle
do a syscall
Traceback (most recent call last):
  File "./oracle_test.py", line 30, in <module>
    subprocess.check_call("sleep 5", shell=True)
  File "/algo/algos2dev4/AlgoOne-EC/third-party-apps/python/lib/python2.6/subprocess.py",
line 457, in check_call
    retcode = call(*popenargs, **kwargs)
  File "/algo/algos2dev4/AlgoOne-EC/third-party-apps/python/lib/python2.6/subprocess.py",
line 444, in call
    return Popen(*popenargs, **kwargs).wait()
  File "/algo/algos2dev4/AlgoOne-EC/third-party-apps/python/lib/python2.6/subprocess.py",
line 1123, in wait
    pid, sts = os.waitpid(self.pid, 0)
OSError: [Errno 4] Interrupted system call

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