[RCU] Mass Deletions

chasd chasd at silveroaks.com
Fri Jan 25 15:22:39 CET 2008

> [25-Jan-2008 00:21:34] PHP Fatal error:  Allowed memory size of  
> 8388608
> bytes exhausted (tried to allocate 2049 bytes) in
> /a/boao/www/webmail/roundcubemail-0.1-rc2/program/lib/imap.inc on  
> line 133

> The HTTP response body was empty, status 200. Changing back all the
> values, deleting all messages with thunderbird (which worked very
> smoothly, btw)

A mailbox with a large number of messages takes a lot of memory to  
display and handle. Thunderbird can simply request more memory from  
your computer. RoundCube depends on the memory on the server, and how  
much of that the server admin has allowed PHP and the web server to  
get. Most admins keep a tight reign on the PHP memory allocation  
because of security issues and the possibility of a runaway process  
causing a type of Denial Of Service to other users. If you crash your  
computer because T-Bird demands too much memory, it only impacts you.  
If your requests on the server through RoundCube cause the server to  
crash, that impacts many more users.

> restarting the webserver; nothing mattered. It kept
> saying that in the logs. To eventually get it to work again I had to
> empty the trash with thunderbird and "compact" all the folders.

Using IMAP to mark messages as deleted doesn't actually delete the  
message. That allows the "undelete" to happen, and also take very  
little time to write just a few bytes of data to mark the message. It  
is a safeguard for click-happy users, and a performance comprimise.  
This isn't a RoundCube thing, it is an IMAP thing. When you "compact"  
or "expunge" a mailbox, that causes the IMAP server to pick through  
the entire mailbox a message at a time, transferring only the "good"  
messages to a temp file, and then overwriting the mailbox file with  
the temp file when it is done. This takes a long time. There is a  
setting in T-Bird to control when this happens - there is a data  
savings size threshold that when exceeded makes a delete trigger an  

> Anyway, not that this is a very likely situation.. It's still quite
> interesting to see that once it's too full, it's too full and you're
> doomed if you don't have other means to access your INBOX :)

Did you try my suggestion of deleting the entire folder from the  
"Folders" tab of "Personal Settings"  ? I don't keep that many  
messages in a mailbox for me to test.

Charles Dostale
System Admin - Silver Oaks Communications
824 17th Street, Moline  IL  61265

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