INFORMIX SERVER / 5725A3900 / C10 - IDS 12.10

It's possible for onstat -z to report a bad mutex and hang the
server...

When the problem occurs, you will see an assertion like this:

    18:10:01  Assert Warning: Bad mutex encountered
    18:10:01   Who: Session(858, informix@u363, 0,
700000fb4b79d50)
                    Thread(1051, onmode_mon, 700000fb4b47a28, 1)
                    File: mt_info.c Line: 1306
    18:10:01   Results: Couldn't reset all the spin locks
    18:10:01   Action: Please notify IBM Informix Technical
Support.
    18:10:01  Raw hex dump of stack located in
/crash/af.8037119.rawstk
    18:10:01  Stack for thread: 1051 onmode_mon
     base: 0x0700000fb6e21000
      len:   69632
       pc: 0x00000001000948b0
      tos: 0x0700000fb6e2fda0
    state: running
       vp: 1

    (oninit)afstack
    (oninit)afhandler
    (oninit)afwarn_interface
    (oninit)dospinlock
    (oninit)zero_profile
    (oninit)onmode_monitor
    (oninit)th_init_initgls
    (oninit)startup

Just because this assertion occurs, that does not mean the hang
will occur.

When the hang occurs, you will see a thread spinning, constantly
running in mt_init_mutex with a stack something like:

    state: running
       vp: 1

    (oninit)poll
    (oninit)mt_spin_lock_wait
    (oninit)mt_init_mutex
    (oninit)ptalloc
    (oninit)ptbld
    (oninit)ptbuild
    (oninit)rspnbuild_sz
    (oninit)sqispnbuild
    (oninit)bldpartn
    (oninit)bldtmpfile
    (oninit)filltemp
    (oninit)scan_open
    (oninit)IPRA.$materialize_viewtmp
    (oninit)IPRA.$materialize_viewtmp
    (oninit)IPRA.$materialize_viewtmp
    (oninit)materialize_viewtmp
    (oninit)prepselect
    (oninit)open_cursor
    (oninit)sql_open
    (oninit)sq_open
    (oninit)sqmain
    (oninit)listen_verify

And the onmode_mon thread will be ready to run with a stack
comparable to:

    state: ready
       vp: 1

    (oninit)yield_processor_mvp
    (oninit)mt_yield
    (oninit)mt_exec
    (oninit)invoke_alarmf
    (oninit)afhandler
    (oninit)afwarn_interface
    (oninit)dospinlock
    (oninit)zero_profile
    (oninit)onmode_monitor
    (oninit)th_init_initgls
    (oninit)startup

In this case, the thread that was running was holding a mutex
and there is a user in the waitlist
waiting for a very long time:

    12507    700000fb3c1c6b8  dbs_partn_6        89185644 0
89185652 3742

89185673 3731

522      3368

4553222  3013

89110462 903

89086555 608

89086494 91

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* USERS AFFECTED:                                              *
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* PROBLEM DESCRIPTION:                                         *
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* RECOMMENDATION:                                              *
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Fixed in IDS 11.70.xC9W2.

not known / see Local fix

Date  - problem reported    :
Date  - problem closed      :
Date  - last modified       :

21.12.2018
08.10.2019
31.08.2020

12.10.xC11