Process waiting after issuing OPEN CURSOR, onstat shows a thread in waiting condition await_MC1 
Author Message
 Process waiting after issuing OPEN CURSOR, onstat shows a thread in waiting condition await_MC1

Hello,

i need some help. We have some strange problems with waiting
conditions on our IDS 7.31FC4 server on Digital unix. The problem
seems to happen from C source with embedded SQL and also when client
applications access the database via ODBC.

What happens from within the C source:

The C source opens a cursor which is just a simple select on a table
with only some rows. The open statement "never" returns (never means
it needs a long time > 1 hour).

onstat shows

session
 id      user      tty    pid  hostname threads   total   used
532      invekos  ttyp8  9391  dg93240     2      327680 321368

tid    name      rstbc      flags       curstk   status
2132   sqlexec   xxxxxx     ----P----    600    
22a85ffb8sleeping(secs:1)
2133   scan_1.0  xxxxxx     Y--------    264      22a8590b8cond wait
(await_MC1)

The process stays here waiting for the condition to resolve for
typically about 20 minutes to some hours. Why this process is waiting,
i can call dbaccess and select from the table without a problem.

Ive no idea what the reason of the condition wait because i didnt
find any explanation of what await_MC1 means.

Greetings, Joerg



Wed, 18 Jun 1902 08:00:00 GMT
 Process waiting after issuing OPEN CURSOR, onstat shows a thread in waiting condition await_MC1

Unfortunately, the bottom on your onstat -g ses was not provided.

Example:
Sess  SQL            Current            Iso Lock       SQL  ISAM F.E.
Id    Stmt type      Database           Lvl Mode       ERR  ERR  Vers
13    -              stores7            CR  Not Wait   0    0    9.03

If the lock mode is set to WAIT or WAIT N (where N is seconds), then
you may be waiting on a lock.  Especially if the ISOLEVEL is not dirty
read.  Try Dirty read.

The other thing is that you are running with PDQ because the query has
2 threads.  You may be gated (waiting on a slot) from the memory grant
manager.  RUn onstat -g mgm and see if your session is active or gated.
Try running without PDQ or running with less than 100.  If you have 100,
you will always gate if someone else is in there.

Ray

Quote:

> Hello,

> i need some help. We have some strange problems with waiting
> conditions on our IDS 7.31FC4 server on Digital unix. The problem
> seems to happen from C source with embedded SQL and also when client
> applications access the database via ODBC.

> What happens from within the C source:

> The C source opens a cursor which is just a simple select on a table
> with only some rows. The open statement "never" returns (never means
> it needs a long time > 1 hour).

> onstat shows

> session
>  id      user      tty    pid  hostname threads   total   used
> 532      invekos  ttyp8  9391  dg93240     2      327680 321368

> tid    name      rstbc      flags       curstk   status
> 2132   sqlexec   xxxxxx     ----P----    600
> 22a85ffb8sleeping(secs:1)
> 2133   scan_1.0  xxxxxx     Y--------    264      22a8590b8cond wait
> (await_MC1)

> The process stays here waiting for the condition to resolve for
> typically about 20 minutes to some hours. Why this process is waiting,
> i can call dbaccess and select from the table without a problem.

> Ive no idea what the reason of the condition wait because i didnt
> find any explanation of what await_MC1 means.

> Greetings, Joerg



Wed, 18 Jun 1902 08:00:00 GMT
 
 [ 2 post ] 

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