PROOF Lite drop in performance

Hello out there,

I am processing a tree with PROOF-lite and I keep running into an intermittent drop in performance. This tends to happen more frequently when processing larger files with larger individual events but I don’t know if that is cause of the problem. See plot below:

When this occurs and I look at top I have many instance of proofserv that aren’t using any CPU.

I have tried changing around the tree cache size with
TProof * p =TProof::Open();
p->SetParameter(“PROOF_CacheSize”,Larger Number here);

But that doesn’t seem to help consistently.

I am using ROOT 5.34.09 and I am on a:
uname -a
Linux pike 3.2.0-4-amd64 #1 SMP Debian 3.2.63-2 x86_64 GNU/Linux



How many workers do you have?

Could you produce the performance tree (see for one run and make it available some how?

G. Ganis

Thanks, for getting back to me,
I have tried it with a variety of different number of workers. Typically between 10-32. I made a performance tree for a run with 20 workers. You can get it from the link below hopefully. … .root?dl=0

Thanks for the file and sorry if it took so long.

The file corresponds to a run which looks rather ‘normal’ I would say. The initial measurement of the performance is not realistic and it stabilise after a few packets.

In this run, all 20 workers are working until the end as show in the plot (perf.png; the finishing time has a spread of < 1 s) and each worker gets reasonably the same events and packets (evtdist.png).

It is true that a couple of files get fragmented in more packets that the others.
Can you try again by setting

proof->SetParameter("PROOF_Packetizer", "TPacketizer")
proof->SetParameter("PROOF_MaxSlavesPerNode", (Long_t)20)

This packetizer maybe more appropriate for these runs (it is the default in current PROOF).

G. Ganis