|Message: Re: random num generator initialization||Not Logged In (login)|
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When submitting many parallel jobs, it is indeed essential to use different random number generator seeds. What I do is use the event number as the seed, at the beginning of each event. Then the problem reduces to making sure that each job uses different event numbers (e.g. via command-line arguments specifying first and last event numbers). This has several advantages:
* the seed is simply an integer * you don't need to keep track of the seeds used * usually you need to use different event numbers anyway * no dependence on non-portable initializers (such as your problem) * you can re-run the entire job * you can re-run INDIVIDUAL EVENTS
This last is the most important reason to do this: often when you run thousands or millions of events you get a few "outlier" events that are far outside the normal distribution of some histogram. All you need to do is determine their event numbers, and you can re-run them with visualization enabled and SEE what happened. I have a feature in the histogramming tool I use that makes this easy.
The default Geant4 pseudo random number generator (from CLHEP) guarantees independent streams for seeds in the range 0 to 900,000,000 -- that's more than enough events for my purposes.
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