[Zope] Re: Zope or Python blocking on select()

[dswift at apmindsf.com]

Hi Tres,

Thanks for the reply.  I have provided a couple of notes below, and I am copying
to the list:

Quoting Tres Seaver <tseaver at zope.com>:

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> David Swift wrote:
>
> | Running Zwiki 0.36 on Zope 2.7.4-0 on Python 2.4, glibc-2.3.4-3, kernel
> | 2.4.22-nptl (fedora core 1).
>
> Python 2.3.4 is the recommended, supported version of Python.

Understood - we were running on Python 2.3.3, using Zope 2.7.0 on a 2.4.18
kernel previously.  I had hoped to take advantage of bugfixes in threading on
Python 2.4.  Nevertheless, since I also see this delay using Python 2.3.3 on the
new machine, I am pretty certain it is not a problem with Python.  I am also
pretty certain it is not Zope 2.7.4 per se, as I see the same behavior when
using 2.7.3 on the new machine.  I really suspect I have left out some critical
piece of configuration, but I am lost as to what that may be.

>
> | Whenever we hit a ZWiki page, there is a delay of 8 seconds before the
> | first page is sent.  Subsequent objects for that request are sent in
> | reasonable (i.e. sub-second) times.  Every individual page request seems
> | to cause this delay.  I have tried all 3 ways of setting the
> | LD_ASSUME_KERNEL variable, tried recompiling Python using the
> | '--with-lib=' option for the different thread libraries, tried Python
> | 2.3.3, and all this still gives the same result - a nasty 8 seconds delay.
>
> It looks as though your delay is in communicating with a ZEO server --
> the speedup after first load would be explained by the presence of the
> object in the ZEO client cache.
>

We are not using a ZEO server, we are still on filestorage.  I wish I could use
ZEO, but when I first set it up, I think I hit this problem as well, and I went
back to filestorage.

I am also pretty certain that the pages are not being cached.  Every time I
click on a ZWiki link, or click the 'FrontPage' link at the top of a ZWiki
page, we experience the delay.  As I said, every individual page request has
this delay, no matter how many times the pages have been loaded previously. 
Looking into the detailed cache debug info for the instance, I never see a
ZWiki page with a count higher than 1.

> | Has anyone else run into a delay like this?  Is anyone using a similar
> | kernel/Python/Zope combination successfully?
>
> I run Zope 2.7.4 with ZEO (on the same machine) on FC1 without seeing
> such issues, using a Python built for the purpose (I don't reuse
> /usr/bin/python).  I don't see such issues there.
>

Good information, thanks!  I was thinking I had setup a really strange and
unique configuration :-)

I am wondering which version of glibc you have, or if you are using the
LD_ASSUME_KERNEL variable in any way?  Can you also tell me what your
./configure command line looked like when you compiled Python?  I have compiled
both 2.4 and 2.3.3 on the FC1 machine, but perhaps I left something critical
out of the configuration.

> Tres.
> - --
> ===============================================================
> Tres Seaver                                tseaver at zope.com
> Zope Corporation      "Zope Dealers"       http://www.zope.com
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Thanks again,
David

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