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Re: Oracle hangs...Oracle 8.1.7.3 and Solaris 2.7

From: Danisment Gazi Unal <dunal_at_unal-bilisim.com>
Date: Thu, 21 Mar 2002 14:43:34 -0800
Message-ID: <F001.00430597.20020321144334@fatcity.com>


Hello all,

I think problem solving is an art. No one can know every solutions for every problems. If we don't use a methodical way, in other words if we use TEST-AND-SEE way, we waste our time. We should not jump into problem immediately.

For your case:

A- Problem: session/db hangs
We don't know the problem yet. So, we can not talk about memory, IO, network etc. yet. We should not TEST the components one by one and SEE the results. If we don't know how to diagnose memory, what will happen ? or if problem is not related to memory what will happen ? wasting time.

B- Identifiying the problem:
Now, how will we identify the problem ? In your case, your session is hanging while connecting to db.
Which phase:
1- Before handhaking with listener,
Take sql*net client trace in level 16 and see 'err' postfix in the trace file. If there is no error message in trace, ignore this phase. 2- After handshaking is completed but before server process is created, Take listener trace in level 16. If there is no error ignore this phase. 3-after server process is created
Take sql*net server trace for server process. If there is no error here, ignore this phase.

sql*net trace files include OS specific errors too. So, They can give you some directions.
Note: Trace files may not include any errors. Check if trace file includes wait-calls from next layer. I mean client requested a server port, but listener may not have returned a server port to client.

If you don't see any problems in above steps, you should see that a server process is created. Now, debug this process by a debugger such as adb, dbx. You will see which Oracle's kernel functions are called. If debugger continues to write forever, that means process doesn't hang. If it repeats same kernel funcitons, most probably, it's endless loop. Also, you can dump process states. This can help what is happening there. According to Oracle's last kernel function, we can identify in which function Oracle hangs. You can also take truss,strace,trace output to see last OS call.

Of course we can not write the fix, but at least we have an opportunity to identify the problem.

regards...

"Sutton, Reed" wrote:

> Oracle supports response to my answers was to increase SHMMAX from 128M to
> 4G and SEMMNS to 2000. Upping the semaphores seems like a good idea, but
> when I questioned why we should increase SHMMAX to more than 2x the real
> memory on the machine, the answer was "I had my Unix Guru look at these and
> he recommended the parameters." A little less than what I was hoping for...
>
> At this point I am going to start launching my own investigation, from tips
> from you guys and research on Metalink, to try to find out what these
> processes are doing when the server is hung.
>
> Thanks again for all the help.
>
> Reed
>
> -----Original Message-----
> Sent: Thursday, March 21, 2002 12:51 PM
> To: Multiple recipients of list ORACLE-L
>
> Well, unfortunately we haven't solved the problem yet, so I don't have any
> solutions to share with everyone.
>
> We are using Sun hardware, and we have not run diagnostics on the memory. I
> don't want to dismiss that idea out of hand, but I don't understand how bad
> memory could be affecting only one of the three instances. There are two
> other 8.1.7.3 instances that run fine, never even a hiccup. The server has
> 2GB of memory.
>
> The application that uses this database (when its up) is connecting over the
> network, but when it hangs, you are unable to connect from a remote client
> or from on the server.
>
> I suggested to the support person handling our case that maybe we could try
> using some of the various oradebug options suggested by people on the list
> and suggested on Metalink, but he suggested looking at the following things
> first:
>
> This may be caused by a system resource problem. Was this DB relinked after
> the upgrade? It might help to get the init<sid>.ora's for all the instances
> What is the total size of each SGA? What is the value of the PROCESSES for
> each instance How much physical memory on the system? How much swap space?
> Type sysdef -i |grep SHMMAX Type sysdef -i |grep SEMMNS
>
> Still waiting for his reply to my answers...
>
> Thanks for all ideas you guys have shared.
>
> -----Original Message-----
> Sent: Wednesday, March 20, 2002 11:58 PM
> To: Multiple recipients of list ORACLE-L
>
> Please let us know how you fixed the problem.
>
> Are you using Sun Hardware? can you run diagnostics for the memory?
>
> Are you connecting using IPC(meaning direct) or through TCP(network)? Is it
> the network that is causing problem?
>
> --- "Grabowy, Chris" <cgrabowy_at_fcg.com> wrote:
> > We have a particular database that hangs on a regular basis. Here are
> > the stats and symptoms.
> >
> > Oracle stats
> > ------------------------------------------
> > 8.1.7.3 (highest patch level applied)
> > Solaris 2.7
> > UTF8 character set
> >
> > Symptoms
> > ------------------------------------------
> > Random hanging.
> > Hanging meaning SQL processing stops.
> > New connections "hang".
> > No traces files.
> > No messages in the alert log.
> > Killing the Oracle processes is the only way to recover from the
> > problem.
> >
> > This problem has been reported to Oracle Support, they are now
> > escalating it up.
> >
> > I just wanted to PING the list to see if anyone else has encountered
> > this.
> >
> > TIA!!!
> >
> > Chris
> > --
> > Please see the official ORACLE-L FAQ: http://www.orafaq.com
> > --
> > Author: Grabowy, Chris
> > INET: cgrabowy_at_fcg.com
> >
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> =====
> Mohammed Shakir
> CompuSoft, Inc.
> 11 Heather Way
> East Brunswick, NJ 08816-2825
> (732) 672-0464 (Cell)
> (732) 257-6001 (Home)
>
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> --
> Please see the official ORACLE-L FAQ: http://www.orafaq.com
> --
> Author: Mohammed Shakir
> INET: mshakir08816_at_yahoo.com
>
> Fat City Network Services -- (858) 538-5051 FAX: (858) 538-5051
> San Diego, California -- Public Internet access / Mailing Lists
> --------------------------------------------------------------------
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> to: ListGuru_at_fatcity.com (note EXACT spelling of 'ListGuru') and in the
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> --
> Please see the official ORACLE-L FAQ: http://www.orafaq.com
> --
> Author: Sutton, Reed
> INET: rsutton_at_fcg.com
>
> Fat City Network Services -- (858) 538-5051 FAX: (858) 538-5051
> San Diego, California -- Public Internet access / Mailing Lists
> --------------------------------------------------------------------
> To REMOVE yourself from this mailing list, send an E-Mail message
> to: ListGuru_at_fatcity.com (note EXACT spelling of 'ListGuru') and in
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> also send the HELP command for other information (like subscribing).
> --
> Please see the official ORACLE-L FAQ: http://www.orafaq.com
> --
> Author: Sutton, Reed
> INET: rsutton_at_fcg.com
>
> Fat City Network Services -- (858) 538-5051 FAX: (858) 538-5051
> San Diego, California -- Public Internet access / Mailing Lists
> --------------------------------------------------------------------
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> to: ListGuru_at_fatcity.com (note EXACT spelling of 'ListGuru') and in
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> also send the HELP command for other information (like subscribing).

--
Danisment Gazi Unal
http://www.unal-bilisim.com


-- 
Please see the official ORACLE-L FAQ: http://www.orafaq.com
-- 
Author: Danisment Gazi Unal
  INET: dunal_at_unal-bilisim.com

Fat City Network Services    -- (858) 538-5051  FAX: (858) 538-5051
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Received on Thu Mar 21 2002 - 16:43:34 CST

Original text of this message

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