If you have a down temp smartblob space and choose to drop it
using onspaces, this will cleanly remove the temporary sbspace.
However, if you try to re-create the temporary sbspace then the
onspaces command will hang indefinitely waiting on a mutex,
which results in a blocked checkpoint.
$ onstat -g ath
IBM Informix Dynamic Server Version 12.10.FC3 -- On-Line (CKPT
REQ) -- Up 00:05:59 -- 42096 Kbytes
Blocked:CKPT
Threads:
tid tcb rstcb prty status
vp-class name
...
51 45c876b8 44bf6668 1 sleeping
forever 9cpu dbWorker1
52 45ca7610 44bf5da8 1 sleeping
forever 8cpu dbWorker2
54 45d866b8 44bf77e8 1 cond wait
bp_cond 1cpu bf_priosweep()
55 45d869f8 44bf4368 1 mutex wait
SBSP000002 1cpu onspace
$ onstat -g wmx
Mutexes with waiters:
mid addr name holder lkcnt
waiter waittime
5098 45be9c98 SBSP000002 0 -1 55
584
37
544
...
The issue is that the holder of the mutex has disappeared, and
thus the mutex can never be freed. The stack of the hung thread:
$ onstat -g stk 55
Stack for thread: 55 onspace
base: 0x0000000045d93000
len: 69632
pc: 0x000000000133dbcf
tos: 0x0000000045da1c40
state: mutex wait
vp: 1
(oninit) yield_processor_mvp
(oninit) mt_lock_wait
(oninit) mt_lock_relmutex
(oninit) sba_sbspace_new_dummy_put
(oninit) rsdbsbuild
(oninit) aud_isdbsbuild
(oninit) crspace
(oninit) onspace
(oninit) spawn_thread
(oninit) th_init_initgls
(oninit) startup
The workaround here is to re-start Informix between dropping and
re-creating the temp sbspace. If the instance is hung, you will
have to kill it.
Attempts to drop the temp sbspace in a later version of Informix
12.10 causes a fatal assertion failure:
12:55:53 IBM Informix Dynamic Server Version 12.10.FC6
Software Serial Number AAA#B000000
12:55:53 Assert Failed: Trying to unlock a mutex held by some
other thread
12:55:53 Who: Session(33, informix@server, 25297, 0x44c7efd8)
Thread(61, onspace, 44c3d368, 1)
File: mt.c Line: 9474
12:55:53 SHM Globals and Master Pool/Master Block Adresses:
base: 0x0000000045dc1000
len: 69632
pc: 0x00000000013f4c97
tos: 0x0000000045dcf550
state: running
vp: 1
(oninit) afstack
(oninit) afhandler
(oninit) afcrash_interface
(oninit) mt_unlock_relmutex
(oninit) sba_sbspace_unlock_ent
(oninit) sb_drop_sbspace
(oninit) onspace
(oninit) spawn_thread
(oninit) th_init_initgls
(oninit) startup
All seems to work as expected with non temp sbspaces. |
