[mod_python] Using Twisted inside mod_python

On 5/6/05, Graham Dumpleton <grahamd at dscpl.com.au> wrote:
> 
> jarrod roberson wrote ..
> > On 5/5/05, Graham Dumpleton <grahamd at dscpl.com.au> wrote:
> > > Question to the original poster. Have you added sufficient debug into
> > each
> > > step of the internals of that call so as to know precisely when the 
> code
> > > seems to block?
> >
> >
> > that call basically walks a list filters out some items and builds 
> another
> > list to return
> > I have done alot of basic debugging and the problem is it just hangs 
> apache
> > and I have to kill it.
> > Thus it doesn't print anything out because it doesn't shut down 
> correctly.
> 
> Is your debug using "print" or "apache.log_error()" from mod_python. 


it is apache.log_error()

If the
> latter, it should be logged to Apache log straight away and adding 
> sufficient
> debugging should be able to identify place it stops if it reliably stops 
> in the
> same place. Is there any evidence it stops at the same place? 


yep same place req.write() 

Does Apache
> process go to idle, or does it look to be stuck in a tight loop and 
> hogging
> all the CPU? 


seems that only that req hangs, I enabled the apache server-status mod and 
it seems that
all the req threads go into a (W)ait mode when that call happens and never 
return :-(

Depending on what platform you are using, does use of ktrace,
> ptrace, strace or truss, indicate that Apache process is stuck within 
> certain
> system calls? These tools should be able to pointed at the process using 
> its
> pid. Tools on Mac OS X are good for this sort of debugging as can show 
> where
> different threads are and whether they are waiting on locks etc.


I am using OSX 10.4 so I will look into what it can do, I just got my 
PowerBook in March so that is still a learning curve.

> Do you know that a separate thread can't call into Twisted
> > > unless it uses appropriate mechanisms?
> >
> >
> > I do now, what I don't know is what "appropriate mechanisms" is 
> specifically
> 
> I don't use Twisted, but based on recent comp.lang.python post, there is a
> call "callFromThread". Example on the new group was:
> 
> import time
> from twisted.internet import reactor
> 
> def shutdown():
> 
> time.sleep(3)
> print "stopping"
> reactor.callFromThread(reactor .stop)
> 
> reactor.callInThread(shutdown)
> reactor.run()
> 
> Don't know much more than that.
> 
> Graham



Awesome, thanks for the advice I will go and try all that stuff!
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