Many imapd Threads Stuck in nslogv - logging bottleneck (Doc ID 1410158.1)

Last updated on SEPTEMBER 14, 2016

Applies to:

Oracle Communications Messaging Server - Version 5.2.0 and later
Information in this document applies to any platform.

Symptoms

IMAP not responding.  Using pstack on imapd processes shows many threads in nslogv like:

-----------------  lwp# 1780 / thread# 1780  --------------------
 ffffffff7b1d82f4 lwp_park (0, 0, 0)
 ffffffff7da9afb4 nslogv (0, 25, ffffffff7e017470, fffffffe91713888, ffffffff7b349020, 0) + 4e4
 ffffffff7da9aa50 nslog (0, 25, ffffffff7e017470, 10c2e82dc, 10c2e7c78, 7dc) + 40
 ffffffff7e0108c4 proc_cleanup (2, 9, f, 2d, 1b, 0) + 174
 0000000100019b14 __1cOunauthenticate6FpnIimap_ctx__v_ (1, ...
 0000000100019f2c __1cJshut_down6FpnIimap_ctx__v_ (...
 ffffffff7d80faf8 GDispCx_Dispatch (1002d7e18, 1098d3198, 10b4bdfe8, 0, 0, 0) + 208
 ffffffff7d810470 GDispCx_InternalWork (10b4bdfe8, 14000, 0, 0, ffffffff7d8100e8, 1) + 388
 ffffffff7b1d8254 _lwp_start (0, 0, 0, 0, 0, 0)

It seems like the act of logging messages to the log files has become a bottleneck causing the performance problem.

Exactly which IMAP commands are indicated by the thread stacks is irrelevant.  The problem is to do with anything which generates log messages.

Changes

Possibly increase in overall system usage or number of users; or reduced free disk space.
Possibly change in loglevel config options.

Cause

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