 | | | ora-04031 | ora-04031 2004-03-11 - By Tim Johnston
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Hi George...
You mention that the shared pool is "huge" and "most of it is
unused"... Do you have any measurements of this? As Chris mentioned,
what's the size of your largest free chunk? It doesn't matter if you
have 2 GB of free space if the largest free chunk is only 1M and you
need 1.5 M then you're in trouble... The classic swiss cheese memory
issue... Here's a simple example...
Here is your free memory... X means it's free and Y means used... You
start your instance and it's all free space... My imaginary example
contains 36 chunks...
XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX
Now... You start performing work... Memory chunks are allocated and
deallocated as time goes by... You end up with a memory area that looks
something like...
XXXAXXXAXXAXXXAXXXAXXXAXXAXAXXXAXXAX
Now... I look at total space and see that 26 out of the 36 chunks are
free... That means you're over 70% free space... But, can you
allocated a contiguous chunk of XXXX? No...
So, you have to start looking at how big your chunks are and why you're
so fragmented... Are you using bind variables? I'm guessing no between
the fragmentation problem and the "huge" SGA statement... The one thing
that throws me for a loop is the TOAD vs OAS thing... I'm guessing the
experiment is impure... How did you perform it? Does the same thing
happen in SQL*Plus? Do you have the same level of activity on the
database? Is it repeatable? etc...
Tim
Michael Milligan wrote:
>The error means an object is trying to load in shared memory and can not
>find contiguous space to do so.
>
>Set your sga_max_size higher, so it allows you to dynamically alter sga size
>with the DB running. Also, set your values for shared_memory and
>shared_memory_reserved_space higher. The shared_memory_reserved_space should
>be 10% of your shared_memory space. This reserves space for large
>objects(not talking about LOBs here, just large packages, etc.) that would
>not ordinarily fit.
>
>HTH
>
>Mike
>
>-- --Original Message-- --
>From: Feighery Raymond [mailto:Raymond.Feighery@(protected)]
>Sent: Thursday, March 11, 2004 4:53 AM
>To: 'oracle-l@(protected)'
>Subject: RE: ora-04031 (See http://ora-04031.ora-code.com)
>
>
>I had a similar problem with 9iAS, MTS and the Large Pool. As Apache was
>indefinitely reusing each HTTP child server process for multiple requests
>the memory the child process required in the Large Pool constantly increased
>until ORA-4031 (See http://ORA-4031.ora-code.com).
>
>The solution was to set MaxRequestsPerChild to > 0 (e.g. 50). It defaults to
>0 (unlimited). Setting it to non-zero may incur a small performance hit.
>
>Here's a script I copied from somewhere (sorry unknown author) which may
>help diagnose your problem.
>
>It may also help to set an event e.g. event = "4031 trace name errorstack
>level 4" to generate a trace when the error occurs.
>
>By the way, what version of iAS, RDBMS and OS are you on?
>
>Ray
>
>
>prompt ***********************************
>prompt ***********************************
>prompt Diagnosing ORA-4031 (See http://ORA-4031.ora-code.com)
>prompt ***********************************
>prompt ***********************************
>prompt THE SGA
>select * from v$sgastat;
>PROMPT SHARED_POOL_RESERVED_MIN_ALLOC
>select val.ksppstvl VALUE
>from x$ksppi nam,
>x$ksppsv val
>where nam.indx = val.indx
>and nam.ksppinm = '_shared_pool_reserved_min_alloc'
>order by 1
>/
>SELECT free_space, avg_free_size, used_space,
>avg_used_size, request_failures, last_failure_size
>FROM v$shared_pool_reserved;
>prompt The ORA-04031 (See http://ORA-04031.ora-code.com) is a result of lack of contiguous space in the shared
>pool
>prompt reserved space if:
>prompt REQUEST_FAILURES is > 0 and LAST_FAILURE_SIZE is >
>prompt SHARED_POOL_RESERVED_MIN_ALLOC.
>prompt To resolve this consider increasing SHARED_POOL_RESERVED_MIN_ALLOC to
>lower
>prompt the number of objects being cached into the shared pool reserved
>space and
>prompt increase SHARED_POOL_RESERVED_SIZE and SHARED_POOL_SIZE to increase
>the
>prompt available memory in the shared pool reserved space.
>prompt The ORA-04031 (See http://ORA-04031.ora-code.com) is a result of lack of contiguous space in the library
>cache if:
>prompt REQUEST_FAILURES is > 0 and LAST_FAILURE_SIZE is <
>prompt SHARED_POOL_RESERVED_MIN_ALLOC
>prompt or
>prompt REQUEST_FAILURES is 0 and LAST_FAILURE_SIZE is <
>SHARED_POOL_RESERVED_MIN_ALLOC
>
>
>-- --Original Message-- --
>From: George Leonard [mailto:leonarge@(protected)]
>Sent: Thursday, March 11, 2004 10:23 AM
>To: oracle-l@(protected)
>Subject: RE: ora-04031 (See http://ora-04031.ora-code.com)
>
>
>Hi there
>
>It seems this did not help. (problem was not on the application server
>infrastructure database)
>
>And as for the production database the shared pool is huge and most of it is
>unused and free.
>
>I am looking at scripts to see if I can figure out what the problem is.
>
>
>
>George
>
>__ ____ ____ ____ ____ ____ ____ ____ ____ _____
>
>George Leonard
>Oracle Database Administrator
>Dimension Data (Pty) Ltd
>(Reg. No. 1987/006597/07)
>Tel: (+27 11) 575 0573
>Fax: (+27 11) 576 0573
>E-mail:george.leonard@(protected)
>Web: http://www.didata.co.za
>
>You Have The Obligation to Inform One Honestly of the risk, And As a Person
>You Are Committed to Educate Yourself to the Total Risk In Any Activity!
>Once Informed & Totally Aware of the Risk,
>Every Fool Has the Right to Kill or Injure Themselves as They See Fit!
>
>
>-- --Original Message-- --
>From: oracle-l-bounce@(protected) [mailto:oracle-l-bounce@(protected)]
>On Behalf Of George Leonard
>Sent: 11 March 2004 10:54 AM
>To: oracle-l@(protected)
>Subject: RE: ora-04031 (See http://ora-04031.ora-code.com)
>
>Hi there
>
>We found something interesting, it normally happens on a specific set of
>queries, big ones. What we found if execute via the front end (Oracle
>Application server involved) we get this error, if executed via toad
>directly on the back end we have no problems.
>
>What we are thinking is that the error is actually produced by the
>application servers infrastructure database. We are altering the shared
>pool and buffer cache parameters for this and restarting the environment
>to see if this resolves our problems.
>
>George
>
>__ ____ ____ ____ ____ ____ ____ ____ ____ _____
>
>George Leonard
>Oracle Database Administrator
>Dimension Data (Pty) Ltd
>(Reg. No. 1987/006597/07)
>Tel: (+27 11) 575 0573
>Fax: (+27 11) 576 0573
>E-mail:george.leonard@(protected)
>Web: http://www.didata.co.za
>
>You Have The Obligation to Inform One Honestly of the risk, And As a
>Person
>You Are Committed to Educate Yourself to the Total Risk In Any Activity!
>Once Informed & Totally Aware of the Risk,
>Every Fool Has the Right to Kill or Injure Themselves as They See Fit!
>
>
>
>-- --Original Message-- --
>From: oracle-l-bounce@(protected)
>[mailto:oracle-l-bounce@(protected)] On Behalf Of
>chris@(protected)
>Sent: 11 March 2004 10:47 AM
>To: oracle-l@(protected)
>Subject: Re: ora-04031 (See http://ora-04031.ora-code.com)
>
>George,
>
>Does this always happen even after a shutdown and restart of the
>database?
>It might help to look at the size of the free chunks in the SGA. Steve
>Adam's
>ixora site (www.ixora.com.au) has some excellent scripts for getting the
>size
>of each of the free chunks.
>
>HTH
>
>Chris
>
>
>Quoting George Leonard :
>
>
>
>>Hi all, weird thing, the developers is executing pretty big queries
>>
>>
>via
>
>
>>java. Sometimes on some of the queries they get this error, if they
>>
>>
>take
>
>
>>the SQL and execute it via sqlplus immediate it works no errors.
>>
>>java.sql.SQLException  : ORA-04031 (See http://ORA-04031.ora-code.com): unable to allocate 1553024 bytes of
>>shared memory ("shared pool","select (isoyear * 100) +
>>iso...","Typecheck heap","qry_text : qcpisqt")
>>
>>George
>>
>>__ ____ ____ ____ ____ ____ ____ ____ ____ _____
>>
>>George Leonard
>>Oracle Database Administrator
>>Dimension Data (Pty) Ltd
>>(Reg. No. 1987/006597/07)
>>Tel: (+27 11) 575 0573
>>Fax: (+27 11) 576 0573
>>E-mail:george.leonard@(protected)
>>Web: http://www.didata.co.za
>>
>>You Have The Obligation to Inform One Honestly of the risk, And As a
>>Person
>>You Are Committed to Educate Yourself to the Total Risk In Any
>>
>>
>Activity!
>
>
>>Once Informed & Totally Aware of the Risk,
>>Every Fool Has the Right to Kill or Injure Themselves as They See Fit!
>>
>>
>
>
>
>>
>>
>>"This e-mail is sent on the Terms and Conditions that can be accessed
>>
>>
>by
>
>
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>>
>>
>>
>
>
>Chris Dunscombe
>
>chris@(protected)
>
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--
Regards,
Tim Johnston
Tel: 978-322-4226
Fax: 978-322-4100
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