[Dovecot] More efficient Deleting of a whole folder (or Purging Trash)

[Daniel Watts]

Hi Timo,
> On Jan 29, 2008, at 6:03 PM, Daniel Watts wrote:
>
>> Is there not a more efficient way to do this? If Dovecot knows the 
>> whole folder is being deleted (ie a Trash purge), could it do 
>> something clever with the filesystem to just remove the whole folder?
>
> If you use IMAP DELETE command, it renames the directory to 
> ..DOVECOT-TRASH (or something like it) and only after that it starts 
> unlinking the files. It wouldn't be too difficult to have this return 
> success immediately and then keep deleting the files on the 
> background. I'm not sure if this is worth the trouble though. It would 
> also be possible to do this as a plugin.
Something like that would be great. Would this actually then avoid the 
locking problem described below?
>> Incidently, the command that initially deleted those 35k messages to 
>> Trash took about 1 hour to complete on my server and effectively 
>> locked my account out for all that time. There were also an awlful 
>> lot of these output from my strace:
>>
>> nanosleep({0, 131475000}, NULL)         = 0
>> lstat("/home/virtual/xxx.com/home/admin/Maildir/.Folders.Porter/dovecot-uidlist.lock", 
>> {st_mode=S_IFREG|0600, st_size=0, ...}) = 0
>
> You mean this was in the deleting process, or the other processes? The 
> deleting process should have kept the maildir locked while it was 
> deleting the files, so other processes were locked out. This is by 
> design and can't be changed, at least until I some day add inotify 
> support for maildir synchronization.
You're probably right - another process is probably trying to access the 
folder that is currently being deleted and being prevented from doing 
so. There was an awlful lot of polling going on though - probably man 
tens per second. Not sure if this causes the system to thrash a bit and 
raise load unnecessarily.

If you renamed the folder to *.DOVECOT-DELETED or something you won't 
have another process trying to access the same folder and locking the 
account up.

IMHO this benefit is worth the effort. =)

Daniel