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Date:      Tue, 5 Feb 2008 20:17:54 +0900 (JST)
From:      "Lachlan Michael" <lachlan@lkla.org>
To:        freebsd-questions@freebsd.org
Subject:   Memory Error using Mailman on FreeBSD. How to debug?
Message-ID:  <1153.137.153.0.37.1202210274.squirrel@sm.lkla.org>

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I have a question about debugging a memory error on FreeBSD.

When a user sends an e-mail with an attachment above about 500kB to a very
small mailing list (4 members), Mailman on my server aborts processing
with the error
 MemoryError :  out of memory

After talking on the Mailman list, the advice was that python and Mailman
are just returning the fact that enough memory can't be allocated, and it
could be a FreeBSD problem. Specifically,

> MemoryError is beyond the control of both Mailman and Python. Python is
> requesting additional memory form the OS for the process and is being
> denied. This is some kind of hardware or OS limitation. It could be
> that the OS itself is running out of real or virtual memory or the
> process is running into some process limit. This is a FreeBSD question.

and some sympathy in that

> 500KB is not a big message. This should not be happening. I am only
> guessing, but I think there must be some per-process memory limitation
> in your OS that is set way too low.

I have run memtest previously and found no problems, also no problems when
upgrading ports or world, so I believe the RAM is ok. The machine is
otherwise lightly loaded.

Although I believe I have a very vanilla flavored FreeBSD machine, I
probably have some setting or parameter incorrectly set. Any hints on how
to debug this problem and where to look at?

Machine Details (i386, 1G RAM)
==========================
# sysctl -a | grep version
kern.version: FreeBSD 6.3-PRERELEASE #0: Wed Jan  2 18:46:42 JST 2008
# sysctl -a | grep mem
      memdesc     1     4K       -        1  4096
vm.kmem_size: 335544320
vm.kmem_size_max: 335544320
vm.kmem_size_scale: 3

hw.physmem: 1052151808
hw.usermem: 881700864
hw.realmem: 1065287680

# limits
Resource limits (current):
  cputime          infinity secs
  filesize         infinity kB
  datasize           524288 kB
  stacksize           65536 kB
  coredumpsize     infinity kB
  memoryuse        infinity kB
  memorylocked     infinity kB
  maxprocesses         5547
  openfiles           11095
  sbsize           infinity bytes
  vmemoryuse       infinity kB

For memory problems it seems that vmstat is used, so I'll include output
when the problem occurs (i.e. sending a large attachment) and also when
sending a normal mail to exactly the same list. As far as I can see, there
seems to be plenty of physical memory  available in both cases.

vmstat when problem occurs* (receiving large attachment in mail)
========================================================
procs      memory      page                    disks     faults      cpu
 r b w     avm    fre  flt  re  pi  po  fr  sr ad4 cd0   in   sy  cs us sy id
 1 3 0  355056 225104    0   0   0   0   0   0   0   0  137  275 344  0  1 99
 0 3 0  355056 225104  127   0   0   0 103   0   0   0  154  444 379  0  3 97
 0 3 0  355056 225104   93   0   0   0  69   0   0   0  157  419 387  0  2 98
 0 3 0  355056 225104  127   0   0   0 103   0   0   0  165  459 404  1  1 99
 0 3 0  355056 225100  186   0   0   0 138   0   3   0  185  543 451  0  1 99
 0 3 0  355056 225100  127   0   0   0 103   0   0   0  196  465 467  0  3 97
 0 3 0  356044 224556  341   0   0   0 138   0   0   0  203  980 482  0  3 97
 0 3 0  356068 224332  141   0   0   0 103   0   1   0  643 1775 1356  0 
1 99
 0 3 0  356068 224080    0   0   0   0   0   0   2   0  714 1673 1504  1 
1 97
 0 3 0  356068 223872  127   0   0   0 103   0   1   0  729 1854 1527  1 
4 95
 0 3 0  356068 223664    0   0   0   0   0   0   2   0  735 1675 1545  0 
2 98
 0 3 0  355060 223340 2850   0   0   0 2898   0  38   0  307 5751 1055 13 
6 81
 *1 3 0  355140 223168 11192   0   0   0 10850   0   6   0  244 17322 821
63 17 20
 0 3 0  354688 223524  917   0   0   0 981   0   3   0  196  668 473  1  4 95
 0 3 0  354688 223524   93   0   0   0  69   0   0   0  162  407 399  0  1 99
 0 3 1  354688 223524   34   0   0   0  34   0   0   0  166  312 415  0  1 99
 1 3 0  354688 223524   93   0   0   0  69   0   0   0  163  423 400  0  2 98
 0 3 0  354688 223524   34   0   0   0  34   0   0   0  149  324 372  0  1 99
 0 3 0  354688 223524    0   0   0   0   4   0   7   0  166  271 411  0  1 99
 0 3 0  354688 223524   34   0   0   0  34   0   0   0  170  305 410  1  1 98

vmstat output when no problem** doing the same task
==============================================
 procs      memory      page                    disks     faults      cpu
 r b w     avm    fre  flt  re  pi  po  fr  sr ad4 cd0   in   sy  cs us sy id
 1 3 0  354688 224360  211   0   0   0 181   1   0   0  126  544 335  2  1 98
 0 3 0  354688 224360   96   0   0   0  69   0   0   0  147  412 365  1  1 98
 0 3 0  354688 224360  127   0   0   0 103   0   0   0  146  447 367  0  1 99
 0 3 0  354688 224360  186   0   0   0 138   0   0   0  154  598 383  0  1 99
 0 3 0  354688 224360  127   0   0   0 103   0   2   0  162  462 400  1  4 96
 0 3 0  354688 224360    0   0   0   0   4   0   6   0  159  281 397  0  1 99
 0 2 1  354688 224360  318   0   0   0 247   0   0   0  171  688 425  0  1 99
 0 2 1  354688 224360   93   0   0   0  69   0   0   0  169  409 411  1  1 98
 0 3 0  354688 224360  127   0   0   0 103   0   0   0  170  464 427  0  2 98
 0 3 0  354688 224360  186   0   0   0 138   0   0   0  151  548 374  1  1 98
 0 3 0  354688 224360  127   0   0   0 103   0   0   0  150  445 375  0  2 98
 0 3 0  354688 224360   93   0   0   0  69   0   0   0  144  403 356  0  1 99
 0 3 0  354688 224360   34   0   0   0  34   0   4   0  156  323 401  0  2 98
 0 3 0  354688 224360  186   0   0   0 138   0   0   0  178  555 425  0  2 98
 0 3 0  354688 224360  127   0   0   0 103   0   0   0  171  456 417  1  1 97
 0 3 0  354688 224360   93   0   0   0  69   0   0   0  175  406 417  1  1 98
 0 3 0  354688 224344 1775   0   0   0 1614   0  18   0  246 5384 649  6 
5 89
 1 4 0  366760 214072 2959   0   0   0 293   0  22   0  260 8265 698 35  4 61
 **1 4 0  396320 186384 7154   0   0   0 203   0   8   0  248 13599 615 87
13  0
 0 4 0  398500 184404  683   0   0   0 148   0   8   0  181 1634 439 53  3 44
 0 4 0  398500 184396   37   0   0   0  35   0   0   0  170  347 407  0  2 98
 0 4 0  398536 184376   98   0   0   0  69   0   0   0  168  537 411  0  1 99
 0 4 0  398536 184376  128   0   0   0 104   0   0   0  156  520 393  0  1 99
 0 4 0  398536 184376  186   0   0   0 138   0   0   0  159  536 389  1  1 98
 1 4 0  398536 184376  128   0   0   0 104   0   3   0  166  448 411  0  1 99
 0 4 0  398536 184376   93   0   0   0  69   0   0   0  151  414 372  0  1 99
 0 4 0  398536 184376  128   0   0   0 104   0   0   0  153  437 373  1  1 98
 0 4 0  398536 184376  186   0   0   0 138   0   0   0  157  550 393  0  3 97
 0 4 0  398544 184368  130   0   0   0 104   0   0   0  178  545 428  1  1 97
 0 4 0  399100 184184   61   0   0   0   0   0   0   0  163  379 397  0  1 99

Regards,

Lachlan





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