Shared objects initialization - DB_COMMIT?

Question

Hi,
this question may be somewhat special:
In our project we want to minimize database accesses to certain never-changed customizing.
We implemented a class with static method. In class constructor, we get the customizing from root object of shared memory area.
We followed the steps outlined in Rich Heilman and Thomas Jung ABAP u2013 Next Generation.
In the automatic 'constructor' build method of root object they use CALL FUNCTION 'DB_COMMIT'. Altghough this is processed in a separate task and thus should not harm the caller, I do not understand the use of this statement. 
Also, when reading data, they use a WAIT UP TO 1 SECONDS statement to allow the shared memory object to be in initialized. This causes an implicit database commit which is never wanted. I tried to avoid it by repeating the attach_for_read( ) call until I got the shared memory object. But here I don't know what happens if success never comes.
Where can I read more about shared memory objects? The online help does not provide too much.
Thanks in advance,
Clemens

Answer 1

The DB_COMMIT is needed for the Auto Build option. The Area Constructor was called automatically becuase of this option and the transactional area only be built until a database commit occurs.
As far as the wait, the initialization can take a fraction of a second to a few seconds and is done asychronously.  Therefore you need to halt the processing of your application while it takes place.  The ABAP wait statement puts your dialog work process to sleep and therefore is the most efficient way to pass this time.  You could also check within a loop, but you will be contstant consuming the work process and CPU time.  It might be theoretically processing the loop pass thousands of times instead of just one or twice with the WAIT statement.