It is indeed the case that there was a segmentation fault, reported in
apache error log.
Perhaps, it's not clear, but this problem occurs under posgres under
debian lenny, not sqlite. I am not running web2py as a CGI script. I
am using the web2py deployment script (for setting up apache and
web2py):
<VirtualHost *:80>
WSGIDaemonProcess web2py user=myusername group=myusername \
display-name=%{GROUP}
WSGIProcessGroup web2py
WSGIScriptAlias / /home/myusername/web2py/wsgihandler.py
....
On Jan 8, 9:59 pm, Graham Dumpleton <[email protected]>
wrote:
> You were possibly using a an old version of sqlite which isn't safe to use
> in a multithreaded configuration.
>
> The MPM settings are not going to help in this case as that error could only
> come about because you are using mod_wsgi daemon mode and so application is
> running in distinct process and not those affected by the MPM or its
> settings.
>
> The only other way you could get that error is that you are actually running
> web2py as a CGI script.
>
> Overall, that specific error message means your daemon mode process that is
> running web2py crashed. You would likely find that there is a segmentation
> fault messages in main Apache error log as well at that time.
>
> Crashing could be because of sqlite thread problems, but could also be
> because you are forcing web2py to run in main interpreter of daemon
> processes and at the same time are using a third party C extension module
> for Python that is not safe for use in sub interpreters.
>
> So, ensure sqlite is up to date. And ensure that you have:
>
> WSGIApplicationGroup %{GLOBAL}
>
> in configuration to force use of main interpreter.
>
> Graham
>
> On Sunday, January 9, 2011 6:44:14 AM UTC+11, VP wrote:
>
> > We occasionally got an Apache error so the page didn't get displayed.
> > So I decided to stress test using Apache Bench (ab). It seems the
> > site suffered failure up to 50-100 concurrent connection.
>
> > Apache error log showed this error:
>
> > >>>>>>Premature end of script headers: wsgihandler.py
>
> > After digging around, I found similar discussions and change
> > apache2.conf like this:
>
> > # prefork MPM
> > StartServers 5
> > MinSpareServers 5
> > MaxSpareServers 10
> > MaxClients 256
> > MaxRequestsPerChild 500
> > ServerLimit 256
>
> > Didn't seem to help.
>
> > ====
>
> > A few notes:
>
> > + It appears when I switched to sqlite instead of posgres, I didn't
> > have the problem. (Sqlite had other problems, such as occasional
> > database locking, which is more serious)
>
> > + I am on a VPS with 768MB with 1GB burstable. While I'm doing the
> > stress test with Apache Bench (ab), using free on the server revealed
> > memory usage was about 450MB. (Which is a lot, but is still under
> > limit).
>
> > =====
>
> > In summary, memory was available. But we got this wsgi error in
> > Apache with multiple requests.
>
> > Any idea please?
>
> > Thanks.
>
>
