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Bryan Mongeau
bryan at eevolved.com
Fri Sep 13 17:11:22 EST 2002
Greetings,
I've been playing around with mod_python and have noticed a peculiar behaviour
that perhaps someone could explain to me. As the mod_python documentation
explains, a sub-interpreter is created for each virtual host (default). I
therefore expected global variables within this sub-interpreter to be able to
maintain state between hits. I created a simple script ( included below ) to
observe this behaviour by counting hits in a global variable and printing the
interpreter name.
To my surprise, it seems as if different apache child processes run their
python code in different sub-interpreters even though the interpreter name
remains the same ( virtualhost ). I produced this behaviour by loading the
script in my browser and refreshing (very) rapidly. What happens is the hit
counter eventually returns to zero, meaning that the global variable is no
longer in the namespace. Repeated refreshing causes the hit counter to jump
all over the place as I presume it jumps from one apache child process to
another, each having their own sub-interpreters and global variables.
It seems as if each child process has its own sub-interpreter? Or am I
confused? Was this documented? Enlightenment is greatly appreciated.
Unfortunately the behaviour I am observing is undesired.
Here is the code to demonstrate:
from mod_python import apache
def handler(req):
try:
globals()['hits']+=1
except KeyError:
globals()['hits'] = 0
req.write("interpreter_name=" + req.interpreter )
req.write(" - hits: " + str(globals()['hits']))
return apache.OK
--
Bryan Mongeau
eEvolved Inc. - IT Consulting & Custom Software
http://eevolved.com/
--
"The true function of life, that which is being maximized in the natural
world, is DNA survival. But DNA is not floating free; it is locked up in
living bodies and it has made the most of the levers of power at its
disposal." -- Richard Dawkins
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