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@xxxxxxxxxxxxx] Sent: Thursday, March 11, 2004 4:53 AM To: 'oracle-l@xxxxxxxxxxxxx' Subject: RE: ora-04031
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.
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 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 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 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@xxxxxxxxxxxxx] Sent: Thursday, March 11, 2004 10:23 AM To: oracle-l@xxxxxxxxxxxxx Subject: RE: ora-04031
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
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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@xxxxxxxxxxxxx Web: http://www.didata.co.za
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-----Original Message----- From: oracle-l-bounce@xxxxxxxxxxxxx [mailto:oracle-l-bounce@xxxxxxxxxxxxx] On Behalf Of George Leonard Sent: 11 March 2004 10:54 AM To: oracle-l@xxxxxxxxxxxxx Subject: RE: ora-04031
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@xxxxxxxxxxxxx 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@xxxxxxxxxxxxx [mailto:oracle-l-bounce@xxxxxxxxxxxxx] On Behalf Of chris@xxxxxxxxxxxxxxxxxxxxx Sent: 11 March 2004 10:47 AM To: oracle-l@xxxxxxxxxxxxx Subject: Re: ora-04031
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 queriesvia
java. Sometimes on some of the queries they get this error, if theytake
the SQL and execute it via sqlplus immediate it works no errors.Activity!
java.sql.SQLException: ORA-04031: 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@xxxxxxxxxxxxx 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
Once Informed & Totally Aware of the Risk, Every Fool Has the Right to Kill or Injure Themselves as They See Fit!
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