slapd instance hang during startup

Issue

• service dirsrv start hangs forever
• Last attempt to stop the directory server failed (it was on defunct state), then the process was killed. But then neither /usr/sbin/start-dirsrv nor service dirserv start commands worked.

[ldap5@test ~]$ ps -ef | grep slap
ldap5    72928     1  0 12:26 ?        00:00:04 ./ns-slapd -D /etc/dirsrv/slapd-rhds5 -i /var/run/dirsrv/slapd-rhds5.pid -w /var/run/dirsrv/slapd-rhds5.startpid
ldap5    81441 15840  0 14:42 pts/7    00:00:00 grep slap

• strace output during startup

[ldap5@test ~]$ strace -tt -f -p 72928
Process 72928 attached with 5 threads - interrupt to quit
[pid 73022] 14:43:21.886321 select(0, NULL, NULL, NULL, {0, 103301} <unfinished ...>
[pid 72928] 14:43:21.886487 futex(0x7f03eb65ac1c, FUTEX_WAIT, 69, NULL <unfinished ...>
[pid 73021] 14:43:21.886594 select(0, NULL, NULL, NULL, {0, 13855} <unfinished ...>
[pid 73023] 14:43:21.886638 select(0, NULL, NULL, NULL, {0, 820883} <unfinished ...>
[pid 73020] 14:43:21.886671 select(0, NULL, NULL, NULL, {0, 15211} <unfinished ...>
[pid 73021] 14:43:21.900773 <... select resumed> ) = 0 (Timeout)
[pid 73021] 14:43:21.900957 select(0, NULL, NULL, NULL, {0, 250000} <unfinished ...>
[pid 73020] 14:43:21.902276 <... select resumed> ) = 0 (Timeout)
[pid 73020] 14:43:21.902429 select(0, NULL, NULL, NULL, {0, 100000} <unfinished ...>
[pid 73022] 14:43:21.990000 <... select resumed> ) = 0 (Timeout)
[pid 73022] 14:43:21.990073 select(0, NULL, NULL, NULL, {0, 250000} <unfinished ...>