Tried it, found it could trigger NFS issue. The test is on one machine runs the script to lock the dovecot-uidlist, moving mail into cur/new, append one line to dovecot-uidlist, and unlock it. On another different machine, run one script to SELECT, another script to COPY. Found the similar issue in http://dovecot.org/pipermail/dovecot/2012-February/063539.html
Whether it means the dovecot LDA also needs to run on the same server with
the backend server?
Timo Sirainen
<[email protected]>
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ovecot.org <[email protected]>
cc
02/15/2012 12:25 Subject
PM Re: [Dovecot] index synchronization
during local delivery
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On 15.2.2012, at 6.13, Andy YB Hu wrote:
> I can generate the UID once I create the uidlist lock, and the UID is
> incremental globally.
>
> Some questions:
> 1, Whether I can write the mail to tmp/ after creating
> dovecot-uidlist.lock?
Yes, then you'll just keep the lock longer than necessary.
> 2, I did the 5 steps manually, found that new mail is set to OLD flag, so
> that when SELECT command, it told there was no NEW mail. Looks like need
> to change code in maildir_uidlist_sync_next_uid()?
I guess that means that the mail didn't get a \Recent flag. Wht Dovecot
version is this? Are you saving the mail to new/?
> 3, About the dovecot-uidlist.lock file creation and deletion, I checked
the
> code, there are functions in dovecot like maildir_uidlist_lock_timeout
and
> maildir_uidlist_unlock. If I did that via calling these functions, there
> are lots of extra codes need to call(like auth, mailbox open...).
Yes, way too much work to do that way.
> So the
> question is if I do that in my codes, how to handle the race condition
> correctly? (At least there would be other sessions want to lock the files
> also / already locked it while I want to create the dovecot-uidlist.lock)
It's a typical dotlock file. You can create it with either open(.., O_EXCL)
or creating a temp file and trying to link() it to the .lock file. Or you
can also directly call the file_dotlock_create() in src/lib/file-dotlock.h
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