Wednesday, July 31, 2013

CALCPARALLEL in Essbase - Things worth of knowing...

I am having hard time in writing introduction of this post, thought of writing "Parallelism is one of the most important...." , "Essbase BSO calculation engine can use multiple threads" etc....

But, we all know essbase can use multiple processors for calculating data and that can be enabled by SET CALCPARALLEL command. Let's see how to use it wisely.

Essbase admin guide suggests using parallel calculation to improve the performance. Yes, it is, but this is not true in all cases.

If you do not have any backward dependencies and dynamic calcs in your formula, Essbase will decide a calculation into tasks so that it can run these tasks in different threads.CALCTASKDIMS setting will specifies how many of the sparse dimensions in an outline are used to identify potential tasks that can be run in parallel. If CALCTASKDIMS is set to 3, Essbase takes last 3 sparse dimensions into consideration, and determines number of parallel tasks which can run on parallel. The number of parallel tasks is equal to (or apprx equal to) product of all stored members to be calculated in these 3 dimensions( takes only FIX'ed members in calc). Essbase will divide these tasks to run on number of threads equally based CALCPARALLEL setting.

** Essbase v11.1.2.2 is designed to determine number of CALCTASKDIMS itself. So, we don't need to worry about this at this point.

As usual , we can try best CALCPARALLEL setting with trial and error method. Let's see when to use and not use CALCPARALLEL.

For example, I have a BSO application with 13 dimensions (3 Dense+12 Sparse). I ran a calculation script with CALCPARALLEL 6. This is what i found in logs.

Maximum Number of Lock Blocks: [100] Blocks
Completion Notice Messages: [Disabled]
Calculations On Updated Blocks Only: [Disabled]
Clear Update Status After Full Calculations: [Enabled]
Calculator Cache: [Disabled].
OK/INFO - 1012678 - Calculating in parallel with [6] threads.
OK/INFO - 1012679 - Calculation task schedule [3016,71,1].
OK/INFO - 1012680 - Parallelizing using [2] task dimensions. .
OK/INFO - 1012681 - Empty tasks [2797,71,1].
OK/INFO - 1012672 - Calculator Information Message:

From above logs, Essbase automatically decided to use 2 dimensions to identify parallel tasks ( Essbase decided to use 2 dimensions  because i am using Essbase will use 1 task dimension by default in earlier versions). Because of sparsity in my cube, essbase found 2797 Empty tasks out of 3016 identified tasks. 92% of my tasks are empty in this calculation which is bad. So, in this case, using parallelism is not adding up anything for performance even though it reserved 6 processors, it's not even using 10 % of them.

But one interesting observation i made is, above calculation ran faster in serial mode rather than parallel mode. Along with the processors,Essbase is also using some other resources on server to run calc parallel mode. I used only 6 processors (out of 32 processors in the server) only for this calc, But, Essbase  had hard time in managing 6 processors for the calculation where 92% of tasks are empty.

So, when to use calcparellel?

I will recommend parallel calculation if Empty tasks are at least 40% of identified tasks. We can play around with order of dimensions in the outline and CALCTASKDIMS settings to reduce number of parallel tasks and empty tasks. We decide number processors based on the resource available and other things running on the server etc... Better start with 2 processors.

We recently upgraded from to A guy from Oracle development team told me that they enhanced parallelism in new version. Instead of improving the performance, it has deprived after up gradation. We have tuned parallelism in calcs which are now running better than previous ones. is doing better job in analyzing parallel tasks than previous version. So, tune your calcparallel if calcs are running longer in compared to previous versions.


  1. Thank you for the very helpful post. Minor clarification question: Did you by any chance mean at most 40% of tasks should be empty? So, if it's is greater than 40% CALCPARALLEL should not be used?

    1. Yes, CALCPARELLEL is not recommended if empty tasks are greater than 40%.

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