TRandom3::SetSeed() with PROOF

Hi Rooters,

I am using PROOF-lite with root 5.27.06. In my analysis I use TRandom3 to smear according to a random distribution. I am running my program with PROOF-lite and there is an issue with setting the seed appropriately. Theoretically each time you run an analysis without PROOF and set the seed at the beginning of the run, each request will always correspond to the same random number. Using PROOF this will not be the case, each event will correspond to a different random number for every run.

Every time I run the code, I want to have the same random number for the same event. Does anyone have know of a solution that achieve that?

Note: For these events there is no unique identifying number to set the seed to.




There was some discussion in the past about this problem but I do not think that a solution was designed except re-initializing the seed for each event with a list which could have been saved from a first run.

The way I would do it is to create a THashList of seeds keyed on the event number, e.g. “9845”, for non-data driven runs, or on file+event_number, e.g. “root://”, for data-driven runs . I would add the list to the input list and set the seed wth TRandom3::SetSeed at the beginning of Process .
You could create the list during a first run.

Gerri Ganis