question about py2/py3

[belforte]

Hi
what is it the release number from which it is safe to switch from py2 to py3 for using FWCore ?

CRABClient imports and run the PSet.py, so that defines the python version for CRAB as well.

We currently use python3 for CMSSW_12 and up and python2 for CMSSW up tp 11. But I noticed
that python3 is part of CMSSW since 10_x. So I felt like asking.

CRABClient code is compatible with both py2 and py3, but when it runs inside python3 we can also mix with Rucio python client, which will be convenient.

FYI @mapellidario @novicecpp

[cmsbuild]

A new Issue was created by @belforte Stefano Belforte.

@Dr15Jones, @perrotta, @dpiparo, @rappoccio, @makortel, @smuzaffar can you please review it and eventually sign/assign? Thanks.

cms-bot commands are listed here

[makortel]

assign core

[cmsbuild]

New categories assigned: core

@Dr15Jones,@smuzaffar,@makortel you have been requested to review this Pull request/Issue and eventually sign? Thanks

[makortel]

@belforte Did I understand you correctly that you're asking for the earliest CMSSW release where FWCore.ParameterSet became safe to use from python3?

Adding @davidlange6

[belforte]

that, and FWCore.PythonUtilities.LumiList
and of course dependencies from them which I am not aware of.

[belforte]

hmm.. seems like FWCore.PythonUtilities.LumiList breaks on python3 up to CMSSW_11 as it requires urllib2 . That settles it. Sorry that I asked.

[makortel]

Right, as far as I can tell FWCore.PythonUtilities.LumiList became python3-friendly with cms-sw/cmssw#28439 in CMSSW_11_0_0.

(and asking is always fine!)

[belforte]

ah.. so maybe we can use py3 also for CMSW_11 ? @davidlange6