apache & mod_python

[m.banaouas]

Hi,
bonjour,

witch versions are suitable to use for apache & mod_python ?

Can i install and use "Apache 2.2.3" & "mod_python 3.2.10" (most recent
versions) without facing any known major issue ?

thanks for any help.

[Maxim Sloyko]

Re: apache & mod_python

m.banaouas wrote:

Can i install and use "Apache 2.2.3" & "mod_python 3.2.10" (most recent
versions) without facing any known major issue ?

Works fine for me.
The only "known major issue" you can face is general non-threadsafety
of Python interpreter. So, if you are using Apache MPM, you have to
allow for it, or use framework that does it for you.

[Graham Dumpleton]

Re: apache & mod_python


Maxim Sloyko wrote:

m.banaouas wrote:
>

Can i install and use "Apache 2.2.3" & "mod_python 3.2.10" (most recent
versions) without facing any known major issue ?

Only that to use Apache 2.2 you must have mod_python 3.2.10 or later,
older versions of mod_python do not work with the more recent version
of Apache.

Works fine for me.
The only "known major issue" you can face is general non-threadsafety
of Python interpreter. So, if you are using Apache MPM, you have to
allow for it, or use framework that does it for you.

You answer here is a bit misleading. There are no issues with the
thread safety of the Python interpreter per-se. However, as with any
Python application, whether mod_python is used or not, if multiple
threads are being used your application code may have to be written so
as to cope with access to code/data from multiple threads at the same
time. This is not anything unique to mod_python.

Whether this will be an issue or not is dependent on which Apache MPM
is used, not that the Apache MPM is used as one will always be used.
The specific Apache MPMs where multithreading has to be taken into
consideration are "winnt" on Windows platforms and "worker" on UNIX
platforms. What this all means is that when these MPMs are used there
can be concurrent request handlers executing in distinct threads within
the same Apache processes. Thus, where common data is accessed, it has
to be adequately protected.

For further details on the Apache/mod_python process/interpreter/thread
model, see:

http://www.dscpl.com.au/wiki/ModPython/Articles/TheProcessInterpreterModel

That said, there are sometimes threading issues with mod_python but it
is more to do with the fact that mod_python can use multiple
interpreter instances within a single process. Also, the problems are
not a problem in mod_python, but result from third party C modules for
Python being used which take the simple path of using the simplified
thread API for working with the GIL. Such modules often will not work
properly when used from secondary Python interpreter instances. In
these cases it is a simple matter of telling mod_python to handle
requests which are dependent on those modules within the main Python
interpreter, ie., the very first one which gets created. Where third
party C modules use the full thread API for Python properly, it doesn't
matter which interpreter instance they are used from.

Graham

[m.banaouas]

Re: apache & mod_python

thanks for your answers
The plateform I target is Windows XP (no body is perferct ...).

Concerning multithread , is simultaneous multi http client calls can
present any problem ? I don't think because usually http server fires a
different process for each client call, while Threading is discussed
within the same process, isn't it?

I'm still looking for mod_python 3.2.10 to install it with apache 2.2.3
It seems like I must "build" it before use it.
If there is no other mean I will do it but usually I retrieve "ready to
use" kits.

Graham Dumpleton a écrit :

Maxim Sloyko wrote:

>m.banaouas wrote:
>>

>>Can i install and use "Apache 2.2.3" & "mod_python 3.2.10" (most recent
>>versions) without facing any known major issue ?

>
Only that to use Apache 2.2 you must have mod_python 3.2.10 or later,
older versions of mod_python do not work with the more recent version
of Apache.
>

>Works fine for me.
>The only "known major issue" you can face is general non-threadsafety
>of Python interpreter. So, if you are using Apache MPM, you have to
>allow for it, or use framework that does it for you.

>
You answer here is a bit misleading. There are no issues with the
thread safety of the Python interpreter per-se. However, as with any
Python application, whether mod_python is used or not, if multiple
threads are being used your application code may have to be written so
as to cope with access to code/data from multiple threads at the same
time. This is not anything unique to mod_python.
>
Whether this will be an issue or not is dependent on which Apache MPM
is used, not that the Apache MPM is used as one will always be used.
The specific Apache MPMs where multithreading has to be taken into
consideration are "winnt" on Windows platforms and "worker" on UNIX
platforms. What this all means is that when these MPMs are used there
can be concurrent request handlers executing in distinct threads within
the same Apache processes. Thus, where common data is accessed, it has
to be adequately protected.
>
For further details on the Apache/mod_python process/interpreter/thread
model, see:
>
>

http://www.dscpl.com.au/wiki/ModPython/Articles/TheProcessInterpreterModel

>
That said, there are sometimes threading issues with mod_python but it
is more to do with the fact that mod_python can use multiple
interpreter instances within a single process. Also, the problems are
not a problem in mod_python, but result from third party C modules for
Python being used which take the simple path of using the simplified
thread API for working with the GIL. Such modules often will not work
properly when used from secondary Python interpreter instances. In
these cases it is a simple matter of telling mod_python to handle
requests which are dependent on those modules within the main Python
interpreter, ie., the very first one which gets created. Where third
party C modules use the full thread API for Python properly, it doesn't
matter which interpreter instance they are used from.
>
Graham
>

[Graham Dumpleton]

Re: apache & mod_python


m.banaouas wrote:

thanks for your answers
The plateform I target is Windows XP (no body is perferct ...).
>
Concerning multithread , is simultaneous multi http client calls can
present any problem ? I don't think because usually http server fires a
different process for each client call, while Threading is discussed
within the same process, isn't it?

The use of a separate process to handle each request only applies to
the 'prefork' MPM on UNIX systems. Being on Windows, the 'winnt' MPM is
used and concurrent requests are always handled within different
threads within the same Apache process. The referenced article should
have made that clear.

I'm still looking for mod_python 3.2.10 to install it with apache 2.2.3
It seems like I must "build" it before use it.
If there is no other mean I will do it but usually I retrieve "ready to
use" kits.

See:

http://nicolas.lehuen.com/download/mod_python/

You will find Python 2.5 versions where whereas the official mod_python
download site only has Python 2.3 and 2.4 versions.

Make sure you grab the appropriate version for your combination of
Apache and Python.

Version 3.2.10 is the last stable version although 3.3.0b is in there
as well and has just been put together for final testing before release
for 3.3.

Graham

Graham Dumpleton a écrit :

Maxim Sloyko wrote:

m.banaouas wrote:
>
>Can i install and use "Apache 2.2.3" & "mod_python 3.2.10" (most recent
>versions) without facing any known major issue ?

Only that to use Apache 2.2 you must have mod_python 3.2.10 or later,
older versions of mod_python do not work with the more recent version
of Apache.

Works fine for me.
The only "known major issue" you can face is general non-threadsafety
of Python interpreter. So, if you are using Apache MPM, you have to
allow for it, or use framework that does it for you.

You answer here is a bit misleading. There are no issues with the
thread safety of the Python interpreter per-se. However, as with any
Python application, whether mod_python is used or not, if multiple
threads are being used your application code may have to be written so
as to cope with access to code/data from multiple threads at the same
time. This is not anything unique to mod_python.

Whether this will be an issue or not is dependent on which Apache MPM
is used, not that the Apache MPM is used as one will always be used.
The specific Apache MPMs where multithreading has to be taken into
consideration are "winnt" on Windows platforms and "worker" on UNIX
platforms. What this all means is that when these MPMs are used there
can be concurrent request handlers executing in distinct threads within
the same Apache processes. Thus, where common data is accessed, it has
to be adequately protected.

For further details on the Apache/mod_python process/interpreter/thread
model, see:

http://www.dscpl.com.au/wiki/ModPython/Articles/TheProcessInterpreterModel

That said, there are sometimes threading issues with mod_python but it
is more to do with the fact that mod_python can use multiple
interpreter instances within a single process. Also, the problems are
not a problem in mod_python, but result from third party C modules for
Python being used which take the simple path of using the simplified
thread API for working with the GIL. Such modules often will not work
properly when used from secondary Python interpreter instances. In
these cases it is a simple matter of telling mod_python to handle
requests which are dependent on those modules within the main Python
interpreter, ie., the very first one which gets created. Where third
party C modules use the full thread API for Python properly, it doesn't
matter which interpreter instance they are used from.

Graham

[m.banaouas]

Re: apache & mod_python

Graham Dumpleton a écrit :

m.banaouas wrote:

>thanks for your answers
>The plateform I target is Windows XP (no body is perferct ...).
>>
>Concerning multithread , is simultaneous multi http client calls can
>present any problem ? I don't think because usually http server fires a
>different process for each client call, while Threading is discussed
>within the same process, isn't it?

>
The use of a separate process to handle each request only applies to
the 'prefork' MPM on UNIX systems. Being on Windows, the 'winnt' MPM is
used and concurrent requests are always handled within different
threads within the same Apache process. The referenced article should
have made that clear.

Ok, obviously, i will be concerned by thread architecture under win32.

>I'm still looking for mod_python 3.2.10 to install it with apache 2.2.3
>It seems like I must "build" it before use it.
>If there is no other mean I will do it but usually I retrieve "ready to
>use" kits.

>
See:
>
http://nicolas.lehuen.com/download/mod_python/

I found it too on http://apache.fastorama.com/dist/httpd/modpython/win/

I would like to warn users about a trick while testing this code (widely
proposed):
#
# helloworld.py
#
from mod_python import apache
#
def handler(req):
req.content_typ e = ’text/plain’
req.write("Hell o World!")
return apache.OK

’text/plain’ don't use regular string delimiters (' and ").
so python interpretter is not happy at all ...