[Zope] Pages Half Rendering :(

Dieter Maurer dieter@handshake.de
Sat, 19 Aug 2000 20:38:34 +0200 (CEST)


Hi Chris,

SentChris Withers writes:
 > I experienced the same weird intermittent problem yesterday that I have
 > had on odd ocassions over the last eight months.
 > 
 > Basically, Zope 2.1.6 returns only half a page. By that I mean if I view
 > source, the HTML just stops at some point through the page. The point
 > depends on the actual time, it varies... clicking reload means you get
 > more or less of the page than last time.
 > 
 > All very odd... what makes it worse is that it happens intermittently
 > under certain cirumstances that I can't pin down.
Months ago, I met a similar problem with Zope 2.1.6:

  A non-deterministic amount of image data was returned
  rather than the complete image.

  The analysis revealed a missing thread synchronization
  between the Zope thread producing the image data
  and the ZServer thread delivering this data.

  However, I saw this problem only together with the
  HTTPResponse.write (i.e. streaming output),
  and never when a page or image was delivered traditionally.


When I reported the problem, DC immediatedly answered that
the problem was already fixed in CVS: the threads
were now synchronized.

Maybe, you should take a 2.2 ZServer and use it with your Zope 2.1.6.
I do not know, however, whether this will bring up other problems.


You may also look at my ZServer patch for the above problem.
It definitely is not optimal, because it does not synchronize
the threads but simply prevents ZServer to store large results
in a temporary file. It was this concurrent access to
the temporary file that led to the data loss.
With the patch, I never again had problems with ZServer 2.1.6.

	URL:http://www.dieter.handshake.de/pyprojects/zope/ZServer.pat


Dieter