PROOF and 2 trees


We are using PROOF to process files with 2 trees. We, of course, loop only over one tree (the big one), but for each event we need to look into the other one (the small one with a few hundred of entries). We have solved this issue by opening the files, retrieving the small tree and passing it to PROOF as an input. However when we process a large amount of data we are having problems during merging. The memory in the master (we are using PoD) explodes and ROOT gets stuck and finally crashes. We have the suspect that the problem might be the system trying to merge all the input trees from all the slaves, but we cannot confirm it. Any hint on how to debug this problem or, even better, on how to fix it would be very welcome.

Thank you very much!


Hi Isidro,

Objects in the input list are broadcast one-way to the workers and, in principle, should never get assigned to the output list, which contains the objects merged.
Perhaps you could try to see in the master log file which object is at the origin of the crash. The master is supposed to print out the memory consumption after each merge action (you have to get the raw log file to check that, the log box window is filtering out those service messages).

Cheers, Gerri