Memory leak/CPU load (Was: servername not honored in imapd.c?)

[Aleksandar Milivojevic]

Quoting Simon Matter <simon.matter at ch.sauter-bc.com>:

> Unfortunately I also found a server having problem with it. That's why I
> have removed the new package again.
> In my case one imapd process was in a loop consuming gigabytes of memory
> until it was killed by the kernel. This happened again and again.
> I attached an strace to the process but lost it's output for some stupid
> reason.
> Maybe I can reproduce it later and provide some more information, or Ken
> alreasy knows what the problem is.

Hi Simon,

I'm having similar problem with your 2.3.1-2 RPM package too.  The 
mupdate process starts consuming hundreds megabytes of memory after 
some time.  I restarted it yesterday afternoon, and found it fluctating 
between 180 and 370 megabytes this morning (according to top).  
Attaching with strace hasn't showed it doing anything (waiting in 
accept, more or less).  The load average on the system was sky high 
too.  This was part of my testing setup.  Three users (including cyrus 
admin), two backends, two frontends, completely idle.  No way it needed 
to grow that large.

Seems that CPU is spending most of time in system calls (according to 
top and vmstat):

$ vmstat 10
procs -----------memory---------- ---swap-- -----io---- --system-- ----cpu----
r  b   swpd   free   buff  cache   si   so    bi    bo   in    cs us sy id wa
1  0      0  48696  78436 282840    0    0     5     9  347   141  7 70 23  0
2  0      0  48680  78440 282844    0    0     0    16 1016  1336  7 66 27  0
1  0      0  48760  78440 282844    0    0     0     1 1012  1825  6 85  9  0
...

$ top -u cyrus
top - 08:11:56 up 17:58,  1 user,  load average: 10.51, 11.68, 12.17
Tasks:  64 total,   1 running,  63 sleeping,   0 stopped,   0 zombie
Cpu(s):  8.5% us, 84.3% sy,  0.0% ni,  6.7% id,  0.0% wa,  0.4% hi,  0.2% si
Mem:    515704k total,   468552k used,    47152k free,    78548k buffers
Swap:  2064376k total,        0k used,  2064376k free,   284128k cached

  PID USER      PR  NI  VIRT  RES  SHR S %CPU %MEM    TIME+  COMMAND
2007 cyrus     16   0 29860 1556 1276 S  0.3  0.3   0:11.70 idled
1983 cyrus     16   0  5280 1388 1084 S  0.0  0.3   0:03.55 cyrus-master
2033 cyrus     16   0  180m 2488 1856 S  0.0  0.5   0:00.29 mupdate
2035 cyrus     15   0 31140 2044 1660 S  0.0  0.4   0:00.07 imapd
2036 cyrus     15   0 30632 2016 1636 S  0.0  0.4   0:00.12 pop3d
...

Attaching with strace to mupdate process showed it was simply waiting 
in accept.  Nothing special:

# strace -p 2033
Process 2033 attached - interrupt to quit
accept(4,

I also attempted to attach to it with debugger, but got "ptrace: 
Operation not permitted.".

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