Re: Heapdump Interpretation

Hi,

A heap consists of memory areas named extent. Each extent consists of memory areas named chunks.

Interpretation:

EXTENT 437

   Chunk 925dfe4 sz=     1836    perm      "perm           "  alo=1836
   Chunk  925e710 sz=     1156    recreate  "session heap   "  latch=0


EXTENT 437 ---> extent number
925dfe4          ----> chunk address
sz=                 -----> size of chunk
perm              ------> permanent memory class
"perm           " ------> chunk comment

Memory classes can be the followings:

• Recreatable (can be removed and then recreated when requested. i.e: shared SQL statements)
• Free (free, no object in it)
• Freeable(used in session/call duration. I guess event10046 data is located here)
• Permanent(for permament objects)

Each chunk in same extent is contiguous. For your case, First chunk address(0x925dfe4) + its size(1836) = second chunk address (0x925e710)

You can not identfy the heap as UGA heap yet. Because, there is no heap header in your email.

I had developed a tool named iOraDumpReader at http://www.ubTools.com/products/ioradumpreader/ioradumpreader.html. I'm mentioning here since it is free. But, I stopped developing it since there was no interest in this product.

For your problem:

Shared memory segments such as SGA are included in process address space. So, You may be encoutering this problem. Search metalink for 'pmap' command.

best regards...

Bill Buchan wrote:

> Hi all,
>
> I have a process which is taking up way more memory than I'd expected. The
> process runs a PL/SQL that does some nested loop joins on a PL/SQL table.
>
> The background process is using > 200Mb of private memory and this number
> goes up if we tweak the WHERE clause in the join to return more data.
>
> I did a heapdump of the process and the trace file looks like this (lots of
> stuff trimmed):
>
> ...
> EXTENT 437
> Chunk 925dfe4 sz= 1836 perm "perm " alo=1836
> Chunk 925e710 sz= 1156 recreate "session heap " latch=0
> ds 92693fc sz= 30315156 ct= 440
> b7aa56c sz= 3980
> 92f30a0 sz= 1072
> afb6e34 sz= 16472
> afb2dcc sz= 16472
> afaed64 sz= 16472
> ...
>
> I presume that "session heap" is the UGA for this process'
> session. Basically it goes on like this for several pages with sz anywhere
> between 16k and 1Mb. How can I interpret this? I presume the memory is to
> do with cursor information. This is a sort but the sort area size is only
> 10Mb and cannot account for all the private memory in use.
>
> I'm just trying to decide if this is a reasonable amount of memory to be
> using (i.e. explain what it is using it *for*) and just put up with it, or
> if something has gone wrong. I'm on 8.1.5 on Linux 2.2 (I know, I know...)
>
> Thanks for any insight!
>
> - Bill.
>
> --
> Please see the official ORACLE-L FAQ: http://www.orafaq.com
> --
> Author: Bill Buchan
> INET: wbuchan_at_uk.intasys.com
>
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--
Danisment Gazi Unal

http://www.ubTools.com
Web based Oracle database products



-- 
Please see the official ORACLE-L FAQ: http://www.orafaq.com
-- 
Author: Danisment Gazi Unal (ubTools)
  INET: dunal_at_ubTools.com

Fat City Network Services    -- (858) 538-5051  FAX: (858) 538-5051
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