Help with memory issue - abap memory vs roll area

Question

Hi experts,
with our customer we are using TRM and WebDynpro technology to process Tax forms. We have portal integration. Recently due to performance reasons we were forced to analyze memory consumption and actually we are unable to understand what is happening. In memory inspector we can see much higher total memory than for ABAP total.
For Example, running simple application for form bundle search will produce following memory consumptions:
We do not understand why the Total section is + 12 MB when all ABAP code is just 7 MB?
Another example - opening of a form bundle (FB) leads to cca 32 MB consumption (no matter what type of FB we are opening). Visiting all pages of FB leads to 52 MBs (specific FB, this depends on FB type). Again, when we invoke memory inspector a lot of memory is in Roll Area.
This look like roll area is almost always twice as big as the actual ABAP Application.
Please any suggestions what is happening?
May be just the misunderstanding of roll area. To our knowledge roll area is the area of the internal session managed by memory manager (usually mostly created by extended memory). But why is this area so large when the actual application needs half of the space?
Some discussion suggests that this is due many dead objects released when memory inspector is started. But why is this space still available to the application and not put back to the extended pool? Is there any way how to identify those dead objects?
Thanks a lot

Answer 1

Hi, ORA-4031 in this case can be caused by unrestricted growth of the PGA, thus forcefully reducing the SGA.
We've had this in the past also.
The solution is in older versions to increase the shared_pool_size as you mentioned but with ASMM, this is no longer an option. You can however retrict the growth of the PGA by setting SGA_TARGET.
On our system this now looks like:
SQL> show parameter _target
NAME                                 TYPE                 VALUE
db_flashback_retention_target        integer              1440
memory_max_target                    big integer          10G
memory_target                        big integer          10G
pga_aggregate_target                 big integer          0
sga_target                           big integer          8GSee how we in fact set the max growth of the PGA to 2Gb ( 10Gb - 8Gb)
Try this and see if ot works for you also
Success!!
FJFranken