[Zope] ZEO hogging too much memory

[Wankyu Choi]

Hi all,

I had a nightmare with my ZEO setup last night. Had to drive to the data
center to clean up the mess... in wee hours. (3AM)=20

The ZEO server has 4G RAM and running on RedHat Linux 8 with 2.4.0 =
custom
kernel. Thought it was plenty. I have one ZEO client with 2G RAM

ZEO server: 4G RAM, P4 Xeon Dual (RH Linux with 2.4.0 kernel)
ZEO client:  2G RAM, P3 tualatin Dual (RH Linux with 2.4.0 kernel)

It seems that the server never stops caching the objects  it serves into
memory until kswapd chimes in and starts paging away. kswapd was hogging =
all
resources left and I had to reboot. I wasn't able to type a single =
keystroke
remotely. argh.. a remote reboot  attempt failed miserably...=20

I did some research and found many reported problems with kswapd and =
kernel
2.4.0.

What I'm worried about though is why ZEO let this happen. I did some
experimentation after a clean reboot: adding and reading objects to the =
ZEO
storage with the top utility running on a console.

After an hour, ZEO was using more than 2G of RAM. The objects are just
simple CMF/Plone stuff: documents and small sized images with no
heavy-weight files. The traffic? Minimal. As I was the only one adding =
and
reading stuff.

And this might be a real stupid question but, when I flush cached =
objects
using a ZEO client's management screen, what am I flushing? Objects from =
the
ZEO server's memory or client's? Flushing objects didn't free up any =
memory
on the ZEO server.

Anybody ever had similar problems with ZEO (or Zope per se) hogging
resources?=20

How can I limit the number of objects the ZEO server itself is caching?

Just hope it's not leaking memory.=20

---------------------------------------------------------------
  Wankyu Choi
  CEO/President
  NeoQuest Communications, Inc.
  http://www.zoper.net
  http://www.neoboard.net
---------------------------------------------------------------  =20