I have a big problem with a customers Zope instanse - almost every day it "falls asleep": When you try to access their site it's like no requests get's to the site. I try to stop the instance - and when I start it again I'm told that another process has already locked the database file.
Is it spinning or not responding? There's a great HOWTO on debugging a spinning Zope on zope.org. You may have a race condition or unending recusrsion that only happens on high load. Does the event log tell you anything? Does the request log (z2.log) record requests while the Zope seems to be "asleep"?
Running $ps -ax reveals that their is some stale python processes mathing the PID of the recently stopped Zope instanse ...
This is probably Zope not responding to the kill sent by the stop script. (This suggests that it's stalled somehow.) You'll have to kill it harder. (Think kill -9 in Linux.) This will probably unlock the database file. Otherwise, you should get rid of the Data.fs.lock file. --jcc