Hans Karlsen (talk | contribs) No edit summary |
Hans Karlsen (talk | contribs) No edit summary |
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But this expression is very (extremly) slow. | But this expression is very (extremly) slow. | ||
The main reason for the slowliness is that collect actually build a result of all the results of the inner expression. In our case this is a List of 1 detail,List of 2 details,List of 3 details...List of 6990 details etc. And this is a heavy operation as 7000 thousand lists must be created and filled with 7000*7000/2 objects - and I am not even interested in that result - I only used the Collect operator as a convenient way to act on each. | The main reason for the slowliness is that collect actually build a result of all the results of the inner expression. In our case this is a List of Lists; List of 1 detail,List of 2 details,List of 3 details...List of 6990 details etc. And this is a heavy operation as 7000 thousand lists must be created and filled with 7000*7000/2 objects - and I am not even interested in that result - I only used the Collect operator as a convenient way to act on each. | ||
If I avoid to return the list - and instead return something simple like this: | If I avoid to return the list - and instead return something simple like this: | ||
Sequence{0..7000}->collect(a| vCollectionDetails.add(Detail.Create);0) | Sequence{0..7000}->collect(a| vCollectionDetails.add(Detail.Create);0) | ||
In this case the collect operator returns 1 list with 7000 zeros - very much faster than 24 million references to Detail objects. | In this case the collect operator returns 1 list with 7000 zeros - very much faster than 24 million references to 7000 Detail objects. | ||
Revision as of 12:17, 18 September 2018
I have at occasions been struck by extremely bad performance when it comes to the ocl Collect operator.
After debugging I have concluded that the expression used was wrong compared to my intended usage and need.
Consider this expression:
Sequence{0..7000}->collect(a| vCollectionDetails.add(Detail.Create))
My intention is to create 7000 Detail-objects and put them in the variable vCollectionDetails that has type Collection(Detail)
But this expression is very (extremly) slow.
The main reason for the slowliness is that collect actually build a result of all the results of the inner expression. In our case this is a List of Lists; List of 1 detail,List of 2 details,List of 3 details...List of 6990 details etc. And this is a heavy operation as 7000 thousand lists must be created and filled with 7000*7000/2 objects - and I am not even interested in that result - I only used the Collect operator as a convenient way to act on each.
If I avoid to return the list - and instead return something simple like this:
Sequence{0..7000}->collect(a| vCollectionDetails.add(Detail.Create);0)
In this case the collect operator returns 1 list with 7000 zeros - very much faster than 24 million references to 7000 Detail objects.