work in progress Philippe & Rene

Memory Pools when reading Currently we new/delete – zipped buffer (when no cache) – unzipped buffer – branches target objects The idea is to create a permanent pool for – the unzipped buffer – the target object in case the branch has ownership main point is to reduce memory fragmentatio n

Parallel buffer merge The main bottleneck in parallel applications is the merging of the IO (buffers or files). For example a system with 100 workers can produce 1 Gbyte of data in one minute, then it takes more than 1hour to merge the output files!! The idea is to accumulate per worker large buffers (TreeCache around 20 Mbytes) and send these zipped buffers to one or more IO servers receiving these buffers asynchronously. Once this is implemented, it could also be used to implement a fast file parallel merge on the network.

TTree::GetRestOfEntry In skimming applications, typically one reads one or a few branches to select events, then one wants to read the rest of the event (or a collection of branches). The idea is to sort the buffers for the remaining branches (like the TreeCache is doing) with a MergeRequest. This requires a change in TTree::GetEntry to preload the baskets and a new function like TTree::GetEntry(Long64_t entry, TList *branches)

TStreamerInfo::ReadBuffer Two possible optimisations are under discussion: TVirtualCollectionProxy::At is an expensive non- inlined virtual function called for each member of a collection. Virtuality should be at the level of the collection, not at the member level. The function is currently implemented as a gigantic switch/case within a loop. Explore replacement by pointers to functions and at the same time minimize the number of “ifs” within loops.

TClass::AddRule To simplify the interface for the auto schema evolution, we propose TClass::AddRule(classname,rule) The rules could also be specified in a new file $ROOTSYS/etc/class.rules. We have an immediate candidate for class.rules with the HepMC class HepEvent/GenVertex when calling TFile::MakeProject on Atlas, CMS and LHCb files. – HepEvent m_vertex options=“notOwner”

TMemStat revisited Anar working to get the new collection algorithm working on Linux and MAC (32 & 64 bits versions). Once this is available (Anar at CERN next week) Rene will work on the visualisation/query system (a la TTreePerfStats) to understand memory leaks, fragmentation and abuse of new/delete (hence pools).

GDML interface Andrei has agreed to support the GDML interface (ROOT side).

Graphics & GL Timur will be at CERN for 3 weeks to work on the integration of his 3D algorithms in padgl and the GL viewer.