This makes sense.  Thank you.

On Thursday, November 29, 2012 4:41:56 AM UTC-5, Graham Dumpleton wrote:
>
>
>
>
> On 29 November 2012 01:35, caelumvox <[email protected] <javascript:>>wrote:
>
>> Hello
>>
>> I am using apache2, mod_wsgi, and django.  In my Django code, I do lots 
>> of os.system() and subprocess.Popen() calls which may create background 
>> processes.  My question is, is it possible to configure mod_wsgi to close 
>> open file descriptors before doing an exec()?  Would apache have some sort 
>> of option like this?
>>
>
> No, there is not such ability in Apache or mod_wsgi.
>  
>
>> I would think that this capability could only be available in daemon 
>> mode.  Could daemon mode close all file descriptors except 0, 1, 2, and the 
>> domain socket to apache?
>>
>
> No. There is no way to know which file descriptors it is safe to close and 
> one even has to be careful about assuming 0, 1 and 2 will behave like a 
> normal stdin, stdout and stderr.
>  
>
>> I know of the subprocess.Popen(..., close_fds=True) argument in python, 
>> but I am trying to avoid having to pass this argument for each call.
>>
>
> Overall best practice is that you should do sub process creation from web 
> server processes. This isn't just because of potential for open file 
> descriptors for sockets, log files and shared memory, but also because you 
> can inherit signals in a blocked state that can interfere with the 
> execution of sub processes. This latter issue make it very hard to run 
> certain Java applications as sub processes which rely on signals for some 
> aspect of GC.
>
> The recommended approach is to have a backend service with a less 
> complicated inherited environment and communicate with it to perform the 
> task, including execution of sub processes as necessary.
>
> Graham
>

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