Subsequent to upgrading to a later version of Gen there may be a sudden
decrease in the performance of the Access Gen (TSO) batch extract process.
What advice can be given to improve the performance of the batch extract?
Solution :
To understand how to take steps to improving the performance of the batch
extract, an explanation of how the utility works with the Access Gen (TSO)
cache is first required. There are two distinct parts of the batch extract
process.
Firstly, there is a Model Structure Cache containing the structure of models
stored in the TLIB library. In order to browse a model in Access Gen (TSO),
it’s structure must be stored in the Model Structure Cache. Initially, each
model to be browsed needs to be extracted in it’s entirety. Subsequently an
incremental process takes over for the changes since the last extract took
place. Unchanged models are skipped completely. In general this part of the
process is quick to execute after the first extract has taken place.
The second process extracts action diagrams into the ADLIB library. This
library is used to save extracting action diagrams from the encyclopedia on
demand during the day, which can take a few minutes depending on the size of
the diagram and the machine resources available. Note that whether an action
diagram is stored in the ADLIB or not, the developer is guaranteed to see an
up to date version of an action diagram since if the cached version of an
action diagram is out of date or no cached version exists, then the action
diagram is re-extracted from the encyclopedia.
From any empty ADLIB, the utility extracts a number of action diagrams up to
the limit specified by the batch extract ADLIM parameter. Once the library is
up to date, the utility only extracts those which have changed since the last
action diagram extract. At this point, the runtime is relatively short. The
ADLIM parameter is simply there to prevent excessively long run times when
starting with an empty TLIB. The default setting for this is 100.Subsequent to
an Gen / Advantage Gen upgrade if you started with an empty TLIB, then this
would explain why the utility has a great deal of processing to do in order to
‘catch up’.
Another point to note is that for the benefit of your developers it is
important to note that models are processed in the order in which they are
listed in the SYSIN data. Therefore, it makes sense to have the most
frequently referenced models (usually the development models) at the top of
the list.
If you have done an in-place upgrade of your encyclopedia then you can still
use the ADLIB data from the earlier Gen /Advantage Gen version. There is no
need to extract all the action diagrams again. Similarly, if a DB2
unload/reload or DSN1COPY was used to transfer the data from the old
encyclopedia to a new one, the object id’s internally would be the same, and
the library data can be re-used.