strange behaviour of dovecot

[Masaharu Kawada]

Dear dovecot-list,

Dovecot gives the below error messages and those errors go away after
running 'systemctl restart dovecot'(Restarting dovecot service)', however,
 the same happens after a while later(like after 300 mails delivered).

---
master : Error : service(anvil) : Initial Status notification no received
in 30 seconds, killing the process
master : Error : service(log) : Initial Status notification no received in
30 seconds, killing the process
master : Error : service(ssl-params) : Initial Status notification no
received in 30 seconds, killing the process
master : Error : service(log) :  child 3703 killed with signal 9
---

then the log process is not there so that no mail log gets captured in
maillog:

---
root     28036  0.0  0.0  19864  1604 ?        Ss   11:45   0:00
/usr/sbin/dovecot -F
dovecot  28074  0.0  0.0   9312  1000 ?        S    11:46   0:00
dovecot/anvil
root     28075  0.0  0.0  12324  2084 ?        S    11:46   0:00
dovecot/config
---

Does this have something to do with any limitation in dovecot
configuration?

If anyone in the list ever has similar or same experience, please give me a
clue that shows where to look at from here.

Thanks,

-- 

Masaharu Kawada