On 09/27/2016 07:08 PM, ellie timoney via Info-cyrus wrote:
I wonder if we can see what the old processes are actually doing...
Is there any chance you're able to obtain a backtrace of these?
You can use a command something like:
gdb -p pid /path/to/imapd
where pid is the one of the imapd process ids (which is the last column
in that ls output from /run/cyrus/proc/) and where the correct path to
wherever your imapd executable actually lives (I think this might be
"/usr/lib/cyrus/bin/imapd" on Debian). You should run this command as
the same user that your cyrus server runs as (probably "cyrus").
Once you're in gdb, look for output like "Reading symbols from
/path/to/imapd...". If this line also contains "no debugging symbols
found", then we can't get anything useful like this, just "quit" -> "y"
to exit gdb. But if it does find debugging symbols, great: run "bt" to
obtain a backtrace, then "quit" -> "y" to exit, and send through the
output from the session (probably best to paste the output into a text
file and then attach that to your email).
Another possibility is to trace the system calls. You can use a command
something like this (also as the "cyrus" user):
strace -p pid
Do not blindly email the output from this command, it may contain
sensitive/private content!
Let this run for 10 minutes or so, then press ctrl-c to stop it, and
then I guess kind of try to describe the output, and we can go from
there. If it's very noisy, you've caught it in the middle of doing
something. Wait a little while and try again, or try a different imapd
pid: we're trying to see what the inactive ones are waiting for.
Cheers,
ellie
Ellie, thanks for doing the above "extended debug" version of a reply.
While not a total "nube" to debugging compiled processes, I have not
done it for a long time and never with Linux, so I am unfamiliar with
the tools. Your words are a great help.
I installed and ran gdb on one of our "problem" servers against an
"idled" pid, 16168, and as you suspected, I found this.
Reading symbols from /usr/lib/cyrus/bin/imapd...(no debugging symbols
found)...done.
FYI, I confirmed this pid is indeed Idle according to this line in
/run/cyrus/proc/16168
imap gertrude.ironicdesign.com [192.168.0.16] donations@xxxxxxxxx
cogift.co!user.donations Idle
So I have installed and started strace against idled pid 16168 and am
collecting the output to a file.
sudo -u cyrus strace -p 16168 -t -o cyrusIdled
16168 is a process that was started about two hours ago (before I saw
your email) after I restarted cyrus to clear the old processes before we
reached the max. I added -t to get a time stamp on each line in case I
need to correlate anything weird with what is going on with the
Blackberry (like perhaps it is unable to connect as the owner drives
around?)
I am tailing the log and so far I am seeing a 60-second cycle with
opening three files (donations.lock, cyrus.index, and cyrus.header) and
then ending with closing all three.
Below is the strace output of a typical cycle I am seeing.
Please note the first and last lines in this output snippet. As you can
see by the time stamps, the first line is written at the end of the
previous 1 minute cycle, but what you can't see here is that it is
written without the "= 0 (Timeout)". The next 1 min cycle begins by
adding the "= 0 (Timeout)" to the end of that line and finishes with the
same line again without the "= 0 (Timeout)".
So it looks like the pselect call is timing out after 60 seconds and the
cycle starts over. I have no idea if this is normal. I may install
strace on our dev server and see what the strace output looks like with
a normal IMAP client like Thunderbird.
09:39:08 pselect6(16, [0 15], NULL, NULL, {60, 0}, {[], 8}) = 0 (Timeout)
09:40:08 rt_sigprocmask(SIG_SETMASK, [], NULL, 8) = 0
09:40:08 gettimeofday({1475073608, 554369}, NULL) = 0
09:40:08
open("/run/cyrus/lock/domain/W/cogift.co/U/user/donations.lock",
O_RDWR|O_CREAT|O_TRUNC, 0666) = 19
09:40:08 fcntl(19, F_SETLKW, {l_type=F_RDLCK, l_whence=SEEK_SET,
l_start=0, l_len=0}) = 0
09:40:08 fcntl(12, F_SETLKW, {l_type=F_RDLCK, l_whence=SEEK_SET,
l_start=0, l_len=0}) = 0
09:40:08 fstat(12, {st_mode=S_IFREG|0600, st_size=218344, ...}) = 0
09:40:08 stat("/var/lib/cyrus/mailboxes.db", {st_mode=S_IFREG|0600,
st_size=218344, ...}) = 0
09:40:08 fcntl(12, F_SETLKW, {l_type=F_UNLCK, l_whence=SEEK_SET,
l_start=0, l_len=0}) = 0
09:40:08
open("/var/spool/cyrus/mail/domain/W/cogift.co/U/user/donations/cyrus.index",
O_RDWR) = 20
09:40:08 fstat(20, {st_mode=S_IFREG|0600, st_size=1688, ...}) = 0
09:40:08 mmap(NULL, 16384, PROT_READ, MAP_SHARED, 20, 0) = 0x7f05ab7a9000
09:40:08 fcntl(20, F_SETLKW, {l_type=F_WRLCK, l_whence=SEEK_SET,
l_start=0, l_len=0}) = 0
09:40:08 gettimeofday({1475073608, 555550}, NULL) = 0
09:40:08
stat("/var/spool/cyrus/mail/domain/W/cogift.co/U/user/donations/cyrus.index",
{st_mode=S_IFREG|0600, st_size=1688, ...}) = 0
09:40:08
open("/var/spool/cyrus/mail/domain/W/cogift.co/U/user/donations/cyrus.header",
O_RDONLY) = 21
09:40:08 fstat(21, {st_mode=S_IFREG|0600, st_size=207, ...}) = 0
09:40:08 mmap(NULL, 207, PROT_READ, MAP_SHARED, 21, 0) = 0x7f05ab7a8000
09:40:08 munmap(0x7f05ab7a8000, 207) = 0
09:40:08 fcntl(20, F_SETLKW, {l_type=F_UNLCK, l_whence=SEEK_SET,
l_start=0, l_len=0}) = 0
09:40:08 gettimeofday({1475073608, 556060}, NULL) = 0
09:40:08 open("/var/lib/cyrus/msg/shutdown", O_RDONLY) = -1 ENOENT (No
such file or directory)
09:40:08 fcntl(14, F_SETLKW, {l_type=F_RDLCK, l_whence=SEEK_SET,
l_start=0, l_len=0}) = 0
09:40:08 fstat(14, {st_mode=S_IFREG|0600, st_size=336, ...}) = 0
09:40:08 stat("/var/lib/cyrus/user_deny.db", {st_mode=S_IFREG|0600,
st_size=336, ...}) = 0
09:40:08 fcntl(14, F_SETLKW, {l_type=F_UNLCK, l_whence=SEEK_SET,
l_start=0, l_len=0}) = 0
09:40:08 fcntl(20, F_SETLKW, {l_type=F_RDLCK, l_whence=SEEK_SET,
l_start=0, l_len=0}) = 0
09:40:08 gettimeofday({1475073608, 556577}, NULL) = 0
09:40:08
stat("/var/spool/cyrus/mail/domain/W/cogift.co/U/user/donations/cyrus.index",
{st_mode=S_IFREG|0600, st_size=1688, ...}) = 0
09:40:08 close(21) = 0
09:40:08
open("/var/spool/cyrus/mail/domain/W/cogift.co/U/user/donations/cyrus.header",
O_RDONLY) = 21
09:40:08 fstat(21, {st_mode=S_IFREG|0600, st_size=207, ...}) = 0
09:40:08 mmap(NULL, 207, PROT_READ, MAP_SHARED, 21, 0) = 0x7f05ab7a8000
09:40:08 munmap(0x7f05ab7a8000, 207) = 0
09:40:08 fcntl(20, F_SETLKW, {l_type=F_UNLCK, l_whence=SEEK_SET,
l_start=0, l_len=0}) = 0
09:40:08 gettimeofday({1475073608, 557191}, NULL) = 0
09:40:08 close(21) = 0
09:40:08 close(20) = 0
09:40:08 munmap(0x7f05ab7a9000, 16384) = 0
09:40:08 close(19) = 0
09:40:08 rt_sigprocmask(SIG_BLOCK, [INT QUIT ALRM TERM CHLD], [], 8) = 0
09:40:08 pselect6(16, [0 15], NULL, NULL, {60, 0}, {[], 8}
I have no idea if the pselect timeout is important, but I wanted to
point out that behavior since it is not apparent from just looking at
the output after the fact.
I am going to let this run all day and will scan it for anything
different from this 60-second cycle and will post results back to the
list around this time tomorrow.
Thanks again for all your help.
--
Andy Dorman
Ironic Design, Inc.
AnteSpam.com
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