1. Kristjan Gulbrandsen March 25, 2004 Collaboration Meeting
PROOF and AnT in PHOBOS
Kristjan Gulbrandsen
March 25, 2004
Collaboration Meeting

2. What is PROOF?
A system integrated into ROOT which allows for interactive analysis of large data sets using parallel processing and I/O
Transparent – difference between running a local session and over multiple computers is minimal
Adaptable – can react network conditions, system performance and multiple architectures
Scalable – no manifest limitations on size

3. PROOF Architecture Client connects to a master server local to cluster
Slave
Client connects to a master server local to cluster
Master server talks to slaves on nodes where (ideally) data is located
Slaves run in parallel
Master server collects results minimizing slow interaction with client
Slave
Master
Slave
Slave
Internet
User

4. } TSelector Interface class TSelector{ (n) Slaves: Begin()
SlaveBegin()
Process()
SlaveTerminate()
Terminate() }
(n) Slaves:
SlaveBegin()
Process() …
SlaveTerminate()
Client:
Begin()
Terminate()
Create
histograms }
code
normally
in for
loops
If a tree exists, tree->MakeSelector()
creates a skeleton class
deriving from TSelector
A copy of each object exists in each slave

5. Using PROOF
Call gROOT->Proof(“proof://<cluster>”) to begin a proof session
A set of file names must be added to a TDSet similar to adding files to a TChain
Call TDSet->Process(<selector file>) where <selector file> contain TSelector code
Additional supporting files/libraries can be used by creating PAR files

6. PROOF Execution Local PC Remote PROOF Cluster proof root proof proof
#proof.conf
slave node1
slave node2
slave node3
slave node4
Local PC
Remote PROOF Cluster
proof
proof = master server
root
stdout/obj
proof
proof = slave server
ana.C
proof
proof
proof
*.root
TFile
node1
ana.C
TNetFile
*.root
$ root
root [0] .x ana.C
$ root
root [0] tree->Process(“ana.C”)
root [1] gROOT->Proof(“remote”)
root [2] dset->Process(“ana.C”)
$ root
root [0] .x ana.C
root [1] gROOT->Proof(“remote”)
$ root
node2
TFile
*.root
node3
TFile
*.root
node4

7. PROOF in PHOBOS PROOF is installed on the Pharm cluster
Newest ROOT version (4.00/03) is needed and exists in /usr/local/root
Proofserver is compiled with libnew (for now to allow PhatII classes to be used without modification
PhatII structure is ideal for transferring individual libraries among slave nodes

8. AnT Trees
A tree format has been created to hold summary information for analyses
Trees are designed to have basic summary information used for analyses and allow pieces of data to be ignored (not read) decreasing I/O
TRefs allowing partial information to be read in while maintaining the ability to cross reference information (i.e. tracks referring to their hits)

9. AnT Structure TriggerInfo: IsCol Tracks[]: L0 Vertex[]: EventInfo: PID
EOct
ERing
TrgT_Extra[]
TrgE_Extra[]
Tracks[]:
PID
Charge
MeandE
SigmadE
Prob
Chi^2
Xprod[3]
Mom[3]
HitArray[]->
EventInfo:
Run
Seq
Ev_No
Date
Time
Polarity
Prim_vtx->
Vertex[]:
Status ID
Prob
Pos[3]
Sigma[3]
Hits[]:
Layer
SensorLabel dE
Pos[3]
Pad[2]
Paddle:
TruncMeanP
TruncMeanN
SumP
SumN
TDiff
ZDC:
SumP
SumN
TZDCP
TZDCN
TOF Info?
PCAL Info?
HitArrays are
being developed

10. Current AnT Trees
Prototype AnT trees currently exist on Pharm (10 runs, 56 Seqs) and can be used
Analysis personnel needed to use the trees and provide information about necessary additions making them useful for many analyses

11. Analysis using AnT/PROOF
AnT/PROOF has been used to generate pt distributions from current data
Using AnT/PROOF speeds up analysis from an hour to a minute
Disabling hit read in
speeds up processing by
more than factor of 10

12. Summary PROOF is ready for use on Pharm.
Simple example macros exist explaining how to use PROOF
AnT trees have been created for quick analysis of large data sets in conjunction with PROOF
Users are needed to test/try both PROOF and AnT to provide information on data format and stress PROOF architecture