I would like to get many files from the grid (alien) and I’m trying to make it so:
Connection works fine:
root  TGrid::Connect("alien://"); //.... root  gGrid->Pwd() (const char *) "/alice/cern.ch/user/b/brumyant/"
Then I made a query and it shows me correct number of files, because I know that Query method it’s just a wrap for find command and I made it directly. Number of files the same.
root  auto res = gGrid->Query("/alice/data/2015/LHC15o/000245145/pass2_UD_CCUP/", "AliESDs.root") (TGridResult *) @0x7fffd5c10f40 root  res->GetEntries() (int) 16608
But here problems occurred: I can’t get name of files:
root  res->GetFileName(0) (const char *) nullptr
How can I fix it?
And one more question: this is correct way to get many files from the grid?
I have more than 20 000 files, and if I’ll run alien_cp that it will take forever. So my idea is to run it
via few parallel processes, so I’ve done it with python, but then I find out that I can work with grid directly from the root, so probably it will help me to avoid python multiprocessing.
root-config --arch --platform --version linuxx8664gcc linux 6.18/04