ctl_deliver hangs

[Dmitry Sergienko]

I use Cyrus 2.1.9. Sometimes ctl_deliver hangs until I restart cyrus.
Looks like it waits for unlocking of deliver.db. That's what ktrace shows:
  54735 ctl_deliver CALL  pread(0x5,0x282b47d4,0x2000,0,0x27e000,0)
  54735 ctl_deliver GIO   fd 5 read 8192 bytes
[....skip....] 
K38 at yahoo.com>\0user.atbmarket\0000\^D\0\^Argэ>a+\0\^A<618DCCJLLF3C6H57\
@translit.ru>\0user.servag\0da\^D\0\^A\^Srш>1H\0\^A<6186081.10545702618\
         07.JavaMail.root at agent3.ientrymail.com>\0user.loveme\0J"
  54735 ctl_deliver RET   pread 8192/0x2000
  54735 ctl_deliver CALL  select(0,0,0,0,0xbfbff854)
  54735 ctl_deliver RET   select 0
  54735 ctl_deliver CALL  select(0,0,0,0,0xbfbff854)
  54735 ctl_deliver RET   select 0
  54735 ctl_deliver CALL  select(0,0,0,0,0xbfbff854)
  54735 ctl_deliver RET   select 0
  54735 ctl_deliver CALL  select(0,0,0,0,0xbfbff854)
  54735 ctl_deliver RET   select 0
  54735 ctl_deliver CALL  select(0,0,0,0,0xbfbff854)
  54735 ctl_deliver RET   select 0
  54735 ctl_deliver CALL  select(0,0,0,0,0xbfbff854)
  54735 ctl_deliver RET   select 0


and select waits until kill of program.

I use db3_nosync as deliver backend.
Version:
Sleepycat Software: Berkeley DB 3.3.11: (July 12, 2001)

Can I avoid such hangs?

-- 
Best wishes,
Dmitry Sergienko