Okay, I didn't get any reply to my previous post (see below). The issue has now taken on a new element.
I have confirmed what appears to be a race condition with multiple IMAP connections to UW-IMAP that occurs when a user is logged in to rcmail and begins to download a large attachment. If the attachment doesn't complete its download sequence before the next scheduled check (1, 3, or 5 min) for new mail, the subsequent login to the IMAP Server causes UW-IMAP to kill the process that is downloading the attachment in favor of the new login connection. Here is a maillog example:
Sep 15 16:35:08 jwhatley imapd[70218]: Login user=jwhatley host=xxxxx.net [174.xxx.xxx.xxx] Sep 15 16:35:08 jwhatley imapd[70167]: Killed (lost mailbox lock) user=jwhatley host=xxxxx.net [174.xxx.xxx.xxx]
I understand that UW-IMAP is old and that we should consider replacing with Dovecot or Courier, but I would like to explore the issue before initiating such a recommendation.
I would really appreciate some feedback on this issue. Someone, perhaps Alec, could give me some guidance?
More specifically and in the interim, I need to know where in the code to change the option 1, 3, 5 minute(s) so that I can increase the maximum available time between checking for new mail. Or, in the alternative, is there any provision within the code for suspending checks while attachments are being downloaded?
Thank you all in advance for any assistance you can render.
Regards,
Jake Whatley
From: Jacob Whatley [mailto:jwhatley@rhyton.com] Sent: Thursday, September 09, 2010 11:34 AM To: 'dev@lists.roundcube.net' Subject: Revisiting ancient issue - Apache2 100% CPU when competing for UW-IMAP
I saw that this issue was identified and confirmed in 2008, but I was wondering if anyone had any further information on preventing 100% CPU processes in Apache2 when RCM loses the fight between competing connections to UW-IMAP (having RCM open while Outlook is also open and checking mail).
We have a system in place to kill these resource hogs, but I want to see if anyone has a better solution, aside from dumping UW-IMAP.
Thanks!
Jacob Whatley
List info: http://lists.roundcube.net/dev/ BT/aba52c80