dovecot/config processes open, and consuming all memory

[filipe at digirati.com.br]

I'm having strange behavior in dovecot 2.3.16.
It's opening dozens of dovecot/config process and consuming all server 
memory. Normally each process consumes between 700Mb and 1Gb of ram.

Would anyone have an idea about this?

service config {
   vsz_limit = 2048M
   idle_kill = 60s
   service_count = 1024
}

pstree
systemd─┬─ModemManager───2*[{ModemManager}]
         ├─agetty
         ├─cron
         ├─dbus-daemon
         ├─dovecot─┬─anvil
         │         ├─6*[auth]
         │         ├─46*[config]
         │         ├─1212*[imap]
         │         ├─155*[imap-login]
         │         ├─12*[lmtp]
         │         ├─38*[log]
         │         ├─10*[managesieve]
         │         ├─19*[pop3]
         │         ├─3*[pop3-login]
         │         └─18*[stats]


root       45831  0.0  1.1 774688 752732 ?       S    09:31 0:31 
dovecot/config
root      388792  0.0  1.1 775060 753276 ?       S    14:00   0:15 
dovecot/config
root      510685  0.0  1.1 775384 753604 ?       S    15:06   0:20 
dovecot/config
root      675638  0.0  1.1 775348 753620 ?       S    16:56   0:15 
dovecot/config
root      795375  0.0  1.1 775460 753516 ?       S    18:03   0:07 
dovecot/config
root      798754  0.2  1.1 775592 753712 ?       S    18:05   0:30 
dovecot/config
root     1082696  0.2  1.1 774892 753216 ?       S    21:10   0:07 
dovecot/config
root     1098433  0.4  1.1 774924 753244 ?       S    21:33   0:07 
dovecot/config
root     1109255  0.9  1.1 774924 753344 ?       S    21:50   0:07 
dovecot/config
root     1112976  2.0  1.1 774956 753528 ?       S    21:57   0:07 
dovecot/config
root     1114137  3.0  1.1 775028 753308 ?       S    21:59   0:07 
dovecot/config
root     1115382  5.4  1.1 774924 753496 ?       S    22:01   0:06 
dovecot/config
root     1883627  0.0  1.1 759120 728832 ?       S    Aug11   0:07 
dovecot/config
root     1889705  0.0  1.8 1251460 1221872 ?     S    Aug11   0:11 
dovecot/config
root     1895022  0.0  1.8 1253280 1224284 ?     S    Aug11   0:11 
dovecot/config
root     1900690  0.0  1.8 1255684 1227528 ?     S    Aug11   0:12 
dovecot/config
root     1905648  0.0  1.8 1257880 1229912 ?     S    Aug11   0:12 
dovecot/config
root     1910857  0.0  1.8 1259156 1231552 ?     S    Aug11   0:12 
dovecot/config
root     1914332  0.0  1.1 764328 736552 ?       S    Aug11   0:20 
dovecot/config
root     2343896  0.0  1.8 1259472 1231516 ?     S    Aug11   0:12 
dovecot/config
root     2346351  0.0  1.8 1259472 1231836 ?     S    Aug11   0:13 
dovecot/config
root     2348559  0.0  1.1 764704 736440 ?       S    Aug11   0:14 
dovecot/config
root     2445701  0.0  1.1 764276 736540 ?       S    Aug11   0:19 
dovecot/config
root     2572525  0.0  1.1 764640 736880 ?       S    Aug11   0:18 
dovecot/config
root     2734251  0.0  1.1 764776 737696 ?       S    Aug11   0:08 
dovecot/config
root     2740980  0.0  1.1 764768 737244 ?       S    Aug11   0:17 
dovecot/config
root     2899925  0.0  1.1 764624 737760 ?       S    Aug11   0:43 
dovecot/config
root     3517063  0.0  1.1 764984 738004 ?       S    Aug11   0:09 
dovecot/config
root     3541465  0.0  1.1 765224 738756 ?       S    Aug11   0:07 
dovecot/config
root     3545589  0.0  1.1 766452 740408 ?       S    Aug11   0:06 
dovecot/config
root     3549259  0.0  1.1 766796 741048 ?       S    Aug11   0:07 
dovecot/config
root     3553902  0.0  1.1 767812 742284 ?       S    Aug11   0:07 
dovecot/config
root     3558080  0.0  1.1 768440 743524 ?       S    Aug11   0:08 
dovecot/config
root     3562091  0.0  1.1 769224 744424 ?       S    Aug11   0:07 
dovecot/config
root     3568721  0.0  1.1 769388 744888 ?       S    Aug11   0:07 
dovecot/config
root     3573024  0.0  1.1 770048 745904 ?       S    Aug11   0:08 
dovecot/config
root     3578416  0.0  1.1 770836 746736 ?       S    Aug11   0:06 
dovecot/config
root     3581765  0.0  1.1 771948 748492 ?       S    Aug11   0:06 
dovecot/config
root     3585837  0.0  1.1 772828 749860 ?       S    Aug11   0:07 
dovecot/config
root     3590276  0.0  1.1 773560 750520 ?       S    Aug11   0:07 
dovecot/config
root     3594640  0.0  1.1 774612 752552 ?       S    Aug11   0:08 
dovecot/config
root     3597417  0.0  1.1 774968 753076 ?       S    Aug11   0:35 
dovecot/config
root     4116314  0.0  1.9 1280496 1258580 ?     S    05:31   0:13 
dovecot/config
root     4118115  0.0  1.1 774688 752556 ?       S    05:33   0:16 
dovecot/config