My PyLucene app freezes when run as a daemon

[David Daney]

Ofer Nave wrote:
> Sorry, I should stated this explicitly:
> 
> I am running on linux 2.6.9.
> 

The version does not really matter.  You cannot call fork from within a 
libgcj based application and use it for much of anything other than exec.

If you want to daemonize, you should do it before calling Jv_RunMain.

David Daney

> -ofer 
> 
>> -----Original Message-----
>> From: java-owner@gcc.gnu.org [mailto:java-owner@gcc.gnu.org] 
>> On Behalf Of Ofer Nave
>> Sent: Friday, March 23, 2007 2:24 PM
>> To: java@gcc.gnu.org
>> Subject: My PyLucene app freezes when run as a daemon
>>
>> This might be a bit off the usual topic range here, but I was 
>> pointed to this list.
>>
>> Background:
>>
>> PyLucene is a GCJ-compiled version of Java Lucene integrated 
>> with Python.
>> http://pylucene.osafoundation.org/
>>
>> Context:
>>
>> I have a PyLucene searcher application running under a 
>> multithreaded python web server called Paste 
>> (http://pythonpaste.org).  I've added a command-line argument 
>> to my script to run the script as a daemon based on the code 
>> in this article: 
>> http://aspn.activestate.com/ASPN/Cookbook/Python/Recipe/278731
>>
>> Problem:
>>
>> When the script is run as a normal process, it works fine.  
>> When it is run as a daemon, it freezes after about a dozen 
>> requests.  The point it's freezing at is in a call to a class 
>> that is known to not be thread-safe, so that might be the 
>> problem - but on the other hand, the only difference between 
>> the good and bad scenarios is whether it's running as a 
>> daemon, so I tend to lean towards that as my top clue.
>>
>> How I Got Here:
>>
>> I posted this to the PyLucene list, and was told: "You might 
>> want to ask java@gcc.gnu.org about daemonizing a process 
>> using libgcj and boehm-gc."  So I'm giving it a shot.  Does 
>> anyone have wisdom on the care and feeding of daemonized 
>> processes built with GCJ?  Is there anything special I need 
>> to know about?
>>
>> Appendix 1 - My daemonize() Function:
>>
>> # call to detach yourself from a terminal def daemonize(logfile=None):
>>     # fork twice to sever any ties
>>     _fork()
>>     os.setsid()
>>     _fork()
>>     os.chdir(WORKDIR)
>>     os.umask(UMASK)
>>
>>     # close standard I/O channels
>>     os.close(0)  # stdin
>>     os.close(1)  # stdout
>>     os.close(2)  # stderr
>>
>>     # redirect standard output channels to logfile
>>     if logfile:
>>         sys.stdout = sys.stderr = logfile
>>
>>     # set up SIGTERM handler for cleanup
>>     signal(SIGTERM, _sigterm_handler)
>>
>> -ofer
>>
>