[Zope-dev] Re: Zope 2.4 crashes -- possible fix identified, other solutions also suggested

[Matthew T. Kromer]

Jeremy Hylton wrote:

>>>>>>"MTK" == Matthew T Kromer <matt@zope.com> writes:
>>>>>>
>
>  MTK> A side effect of shutting off the garbage collector is that you
>  MTK> can have some storage leaks.  We're working on being able to
>  MTK> re-enable the garbage collector so that you don't exhaust
>  MTK> memory over time.
>
>Do you have any more idea about what shutting the garbage collector
>off achieves?  In practice, the garbage collector's most common effect
>is to turn latent bugs into manifest bugs; a bug has trashed part of
>memory and the garbage collector just happens to find it first.  If
>you turn GC off in these cases, you run a little longer, but you're
>running with corrupted memory.
>
>Jeremy
>


Well, one suspicion I have is that (aside from memory corruption caused 
by the compiler sack size bugs and the frame setup bug in 2.1 when 
handling exceptions) ExtensionClasses are providing bogus data to 
modules which aren't checking the flags to see if the GC fields are 
populated.

Some of the people who have tried the modified extensionclass.h which 
pads out the type object to align it with the 2.1 type object THINK they 
have seen a reduction in crashes, but these same folks also have not 
applied fixes for the two known bugs.

Soo... if shutting off GC extends time between crashes for some folks 
from every 15 minutes to 3 times a day, my advise is to shut off GC.