[Zope] Re: RedHat blows up? (another post follow up)

[Dieter Maurer]

FuBuJo wrote at 2008-3-14 19:38 +0000:
> ...
>The behavior we found is that the python process running as the "Zeo Client"
>eventually takes up a large amount of resident memory (1.5 Gig or so), load
>average gets high (1.5 or so), and the end users start experiencing a very
>'slow' experience.

Does your system start swapping?

In this case, you need to take urgent counter measures:

  *  provide more RAM

  *  check your configuration that affect memory consumption.

     The "temporary storage" hosting the sessions is often
     misconfigured. If you put large amounts of data
     in your sessions, this may be a considerable memory hog.

     Maybe, you need to make your ZODB caches smaller or
     reduce the number of concurrent threads.

  *  check whether your application contains memory leaks.

     Unfortunately, this is not easy.

>Even when traffic is removed from the box - you still get a
>large response time (>10s).  This is Linux kernel 2.6.18-8.el5xen.

Python sits on top of the C runtime memory allocation -- and
this allocation does not support compaction. This means that
the memory used in your program is likely to be scattered
all over the process address space. Therefore, even with small
load, you may face large response times when your system is unable
to hold the (usally large) working set in memory.



-- 
Dieter