[Dovecot] dovecot-auth file descriptor usage

[Steven F Siirila]

On Wed, Jan 17, 2007 at 12:48:53AM +0200, Timo Sirainen wrote:
> On Tue, 2007-01-16 at 16:33 -0600, Steven F Siirila wrote:
> > > I'm now just wondering if it's only dovecot-auth that doesn't notice the
> > > socket closing for some reason, or if the imap-login processes proxying
> > > SSL didn't really close the socket after all.
> > 
> > I have attached our dovecot.conf and a "pfiles" (like lsof) output of
> > dovecot-auth, showing all of its open file descriptors.  I hope this helps.
> > If there is anything else I can provide to shed more light, let me know.
> 
> login_processes_count = 32
> 
> This means that Dovecot always keeps extra 32 login processes that don't
> do anything else than wait for new connections. That's not at least
> helping :)

I realize that, but in an environment where there are thousands of IMAP
connections (our UW-IMAP servers) we expect to need more login processes
standing by.

> Anyway, I'd like to get lsof of an imap-login process that is doing SSL
> proxying. Unfortunately I don't think there's any simple way to know
> what processes are doing that and what aren't. Setting
> login_process_count=1 at least makes it more likely that you'll hit the
> right process. If trussing the process shows that it's writing some
> garbage to file descriptor 1, it's probably proxying SSL..

I was able to get one by doing the following:

 1. set login_process_count = 1 and restart dovecot
 2. Determine pid of the one imap-login above (pid 25814)
 3. Truss -f that process, waiting for the first child process to start,
    and extract the pid of that process, and run "pfiles" on that pid:

	( truss -f -p 25814 | & fgrep -v 25814: | head -1 | sed -e 's/:.*//' -e 's/^/pfiles /' > x ) ; sh -x x > pfiles.out

The contents of the pfiles.out file is:

26738:	imap
  Current rlimit: unlimited file descriptors
   0: S_IFSOCK mode:0666 dev:293,0 ino:39965 uid:0 gid:0 size:0
      O_RDWR|O_NONBLOCK
	SOCK_STREAM
	SO_SNDBUF(16384),SO_RCVBUF(5120)
	sockname: AF_UNIX 
   1: S_IFSOCK mode:0666 dev:293,0 ino:39965 uid:0 gid:0 size:0
      O_RDWR|O_NONBLOCK
	SOCK_STREAM
	SO_SNDBUF(16384),SO_RCVBUF(5120)
	sockname: AF_UNIX 
   2: S_IFIFO mode:0000 dev:295,0 ino:2453883 uid:0 gid:1 size:0
      O_RDWR
   3: S_IFCHR mode:0644 dev:287,0 ino:99614726 uid:0 gid:3 rdev:190,1
      O_RDONLY|O_LARGEFILE FD_CLOEXEC
      /devices/pseudo/random at 0:urandom
   4: S_IFIFO mode:0000 dev:295,0 ino:2453884 uid:133702 gid:1000 size:0
      O_RDWR FD_CLOEXEC
   5: S_IFIFO mode:0000 dev:295,0 ino:2453884 uid:133702 gid:1000 size:0
      O_RDWR FD_CLOEXEC
   6: S_IFREG mode:0600 dev:85,53 ino:17665 uid:133702 gid:1000 size:3176
      O_RDWR|O_LARGEFILE
      /home/xxxxxxxx/.imap/INBOX/dovecot.index
   7: S_IFREG mode:0600 dev:85,53 ino:17798 uid:133702 gid:1000 size:89704
      O_RDWR|O_LARGEFILE
      /home/xxxxxxxx/.imap/INBOX/dovecot.index.log

If an lsof is required, I'll have to look into compiling one for Solaris 10.

-- 

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