Re: [Pywebsvcs-talk] Is ZSI thread safe?

[Joshua B. <jrb...@lb...>]

In our last conversation about Apache, Graham roasted me for  
erroneously claiming global variables are of no concern because of  
the python GIL.  It seems I can't get this right, but if you're using  
Apache I recommend looking at previous posts by Graham :)


-josh


On Aug 14, 2007, at 3:53 PM, Graham Dumpleton wrote:

> On Aug 15, 5:23 am, Joshua Boverhof <jrbover...@lbl.gov> wrote:
>> Probably, it has a class attribute "location".  So unless you're
>> writing over this there there is nothing else to worry about.
>>
>> Make sure to look up what the python GIL is in case you haven't come
>> across it yet, however, if you're using Apache mod_python there are
>> real concurrency issues you need to be concerned with.
>
> This claim that there are real concurrency issues with mod_python
> because of the GIL is over inflated and is a common claim used to
> discredit mod_python that doesn't seem to want to go away. :-(
>
> First off, if prefork MPM is used by Apache, it is a total non issue
> as each Apache child process is single threaded.
>
> Second, in worker MPM, because there are multiple Apache child
> processes running concurrently, one can still take advantage of
> multiple cores in a CPU or multiple CPUs.
>
> Third, because all the connection handling, URL mapping, request and
> response content reading/writing is all handled by C code in Apache's
> core, where the GIL is not even held, there are still huge
> opportunities for overlapping processing.
>
> Finally, because all static serving of files, or execution of other
> Apache modules and languages is nothing to do with Python, again no
> GIL is held, so again there are still huge opportunities for
> overlapping processing.
>
> In other words, there is a huge amount of other stuff happening at the
> same time. You would only incur noticeable problems if your Python
> handlers were doing very intensive processing that takes some time in
> pure Python code. Even this would have less impact than using a single
> distinct multithreaded Python process because of the fact that Apache
> spreads requests across multiple processes and is doing all this other
> stuff at the same time allowing it to still use the available CPUs
> effectively. So, Apache is going to handle all this a lot better than
> trying to host a web service in a single Python process using Apache
> as only a proxy.
>
> Graham
>
>> On Aug 9, 2007, at 3:13 PM, Denis Laroche wrote:
>>
>>
>>
>>> Sorry if the question has already been asked. I tried to search in
>>> the archives but got a "timed out" message from the search server.
>>
>>> I'd like to know if it's ok to use an instance of a services
>>> locator (class generated by wsdl2py) in multiple threads.
>>
>>> Thanks in advance.
>>
>>> --
>>> D. Laroche
>>
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