On Tue, 24 May 2005, Doug Hardie wrote:
On May 24, 2005, at 13:21, Stephen Gran wrote:
On Tue, May 24, 2005 at 12:54:47PM -0700, Doug Hardie said:
http://www.lafn.org/clamav/ktrace.html
http://www.lafn.org/clamav/clamd.html
clamav-milter is only one process. It has multiple threads but those are not
visible to the kernel. The problem does not occur immediately with a
database reload. It takes 10 or so minutes before it hangs/quits. I suspect
that the problem occurs when there are active messages that do not complete
before some timeout value. clamav-milter is waiting for everything to go
quiet, but on my receive mail server that never happens. There are always
30-40 active sendmail children. As a result it never goes quiet. I suspect
that clamav-milter eventually gives up and thats when the problem occurs. On
my outgoing mail server which handles considerably less mail, most of the
database updates do not cause a problem. On my test server which handles 3
email daily it never causes a problem.
Just to bring you (and anyone else joining us) up to speed, here's a
description of how it's supposed to work:
When there's a database update, the milter wants everything to be quiet.
So it stops accepting new connections. It then waits for the
currently-running children to finish. Once n_children drops to 0, it
reloads the database and resumes accepting connections.
At least, that's the theory. In practice, n_children isn't ever hitting
0, so it stays in the !accepting state forever. For example, in the
ktrace you posted, n_children dropped from 7 down to 2. The fact that
it never reached 0 is the entire problem. Of course, nobody knows *why*
it isn't reaching 0. It might be from a hung scanner thread, or from a
pthreads race condition, or even a locking issue.
The hope was that getting an strace of each thread of a hung milter
would provide information on which of those causes was at fault, and
perhaps enable us to actually locate the bug.
Damian Menscher
--
-=#| Physics Grad Student & SysAdmin @ U Illinois Urbana-Champaign |#=-
-=#| 488 LLP, 1110 W. Green St, Urbana, IL 61801 Ofc:(217)333-0038 |#=-
-=#| 4602 Beckman, VMIL/MS, Imaging Technology Group:(217)244-3074 |#=-
-=#| <[EMAIL PROTECTED]> www.uiuc.edu/~menscher/ Fax:(217)333-9819 |#=-
-=#| The above opinions are not necessarily those of my employers. |#=-
_______________________________________________
http://lurker.clamav.net/list/clamav-users.html
