IMAP processes out of control

[Shaheen Bakhtiar]

2 x AMD quad Core 64bit 
4G RAM

This morning I woke up to a plethora of complaints that people were not able to access their emails. I remove the aforementioned maxchild from the configurations and restart to server. Once I did that people were able to re-connect with no problems.

I did not have these types of problems with the older version (I believe was 2.3.19). Just since I upgraded to the latest version of Cyrus. 

Current version is:
[root at postoffice ~]# dnf info cyrus-imapd
Last metadata expiration check performed 1:06:02 ago on Wed Sep 23 07:12:41 2015.
Installed Packages
Name        : cyrus-imapd
Arch        : x86_64
Epoch       : 0
Version     : 2.4.17
Release     : 9.fc22

Running on Fedora Core 22 64bit

> On Sep 23, 2015, at 7:44 AM, signaldeveloper at gmail.com wrote:
> 
> Again this is active sync devices that are connecting with a ton of pushed folders. The more you tell it to sync (folders) the more processes it's going to fork for each user folder. Is this affecting performance that bad? What's your hardware? 
> 
> - Paul
> 
>> On Sep 22, 2015, at 7:43 PM, Moby <moby at mobsternet.com> wrote:
>> 
>> 
>> 
>> On 9/22/2015 18:12, Shaheen Bakhtiar wrote:
>>>> On Sep 22, 2015, at 2:17 PM, Andrew Morgan <morgan at orst.edu> wrote:
>>>> 
>>>>> On Tue, 22 Sep 2015, Shaheen Bakhtiar wrote:
>>>>> 
>>>>> It happened again….. although it took longer for it to happen, this has been happening only since the upgrade in Jun.
>>>>> 
>>>>> The number of imap processes continues to increase until the server is completely OOM. the increase is drastic and all of a sudden.
>>>> You should probably set maxchild to a value that won't run your server out of memory.  :)
>>>> 
>>>> Have you looked at the processes to see what they have in common?  For example, sometimes an IMAP client will run amok and make hundreds or thousands of connections.  Or perhaps the processes are all stuck waiting on a lock, etc.
>>>> 
>>>> lsof, strace, netstat, and your Cyrus logs can help a lot.
>>>> 
>>>>   Andy
>>> 
>>> 
>>> [shawn at postoffice ~]$ ps aux | grep imapd | wc -l
>>> 255
>>> [shawn at postoffice ~]# ps aux | grep imapds | wc -l
>>> 1
>>> [shawn at postoffice ~]# ps aux | grep pop3d | wc -l
>>> 9
>>> [shawn at postoffice ~]# ps aux | grep timseived | wc -l
>>> 1
>>> [shawn at postoffice ~]# ps aux | grep lmtpunix | wc -l
>>> 1
>>> 
>>> Based on that output I changed the configuration file (below) adding maxchild. Most likely all my users have their clients open, and from previous monitoring I average about 200 instances of imapd:
>>> 
>>> # standard standalone server implementation
>>> 
>>> START {
>>>  # do not delete this entry!
>>>  recover       cmd="ctl_cyrusdb -r"
>>> 
>>>  # this is only necessary if using idled for IMAP IDLE
>>>  idled         cmd="idled"
>>> }
>>> 
>>> # UNIX sockets start with a slash and are put into /var/lib/imap/sockets
>>> SERVICES {
>>>  # add or remove based on preferences
>>>  imap          cmd="imapd" listen="imap" prefork=5 maxchild=300
>>>  imaps         cmd="imapd -s" listen="imaps" prefork=1 maxchild=100
>>>  pop3          cmd="pop3d" listen="pop3" prefork=3 maxchild=5
>>>  pop3s         cmd="pop3d -s" listen="pop3s" prefork=1 maxchild=5
>>>  sieve         cmd="timsieved" listen="sieve" prefork=0
>>> 
>>>  # these are only necessary if receiving/exporting usenet via NNTP
>>> #  nntp         cmd="nntpd" listen="nntp" prefork=3
>>> #  nntps                cmd="nntpd -s" listen="nntps" prefork=1
>>> 
>>>  # at least one LMTP is required for delivery
>>> #  lmtp         cmd="lmtpd" listen="lmtp" prefork=0
>>>  lmtpunix      cmd="lmtpd" listen="/var/lib/imap/socket/lmtp" prefork=1
>>> 
>>>  # this is only necessary if using notifications
>>> #  notify       cmd="notifyd" listen="/var/lib/imap/socket/notify" proto="udp" prefork=1
>>> }
>>> 
>>> EVENTS {
>>>  # this is required
>>>  checkpoint    cmd="ctl_cyrusdb -c" period=30
>>> 
>>>  # this is only necessary if using duplicate delivery suppression,
>>>  # Sieve or NNTP
>>>  delprune      cmd="cyr_expire -E 3" at=0400
>>> 
>>>  # this is only necessary if caching TLS sessions
>>>  tlsprune      cmd="tls_prune" at=0400
>>> }
>>> 
>>> 
>>> 
>>> Comments, concerns??? I’m going to keep observium open on a separate screen and watch when it starts going up, than do the lsof,netstat, and watch logs to see if I can tell why the sudden upticks.
>>> ----
>>> Cyrus Home Page: http://www.cyrusimap.org/
>>> List Archives/Info: http://lists.andrew.cmu.edu/pipermail/info-cyrus/
>>> To Unsubscribe:
>>> https://lists.andrew.cmu.edu/mailman/listinfo/info-cyrus
>> I have seen that when some of my users fiddle around on their iphone - 
>> usually the complaints start with "I cannot get mail on my phone" and 
>> around the same time the process count starts going up.  Very 
>> intermittent though, and has not occurred since all users upgraded to 
>> IOS 9.  Just my USD 0.02 worth...
>> 
>> -- 
>> --Moby
>> 
>> ----
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> ----
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