[siliataider]

This Pull request:

Changes or fixes:

The RDataLoader does not work when ROOT's ImplicitMT is enabled, in both eager and lazy loading modes. A runtime error is now raised to tell the user.

Caution

This is not possible:

ROOT.EnableImplicitMT(2)

df = RDataFrame(...)
dl = RDataLoader(...)
dl.save(...)

Traceback (most recent call last):
  File "example.py", line 6, in <module>
    dl.save(...)
  ...
RuntimeError: The RDataLoader does not support ImplicitMT, call ROOT.DisableImplicitMT().

Users can still enable ImplicitMT for other parts of their script and disable it for the ML part, as long as:

• It is not enabled when the RDataFrames given to the RDataLoader are created, even if it is disabled just before creating the RDataLoader itself. An RDataFrame requires the same number of slots when starting its event loop as when it was constructed.

Caution

ROOT.EnableImplicitMT(2)
df = RDataFrame(...)

ROOT.DisableImplicitMT()
dl = RDataLoader(...)
dl.save(...)  # RuntimeError

• It is not enabled between the creation of the RDataLoader and the use of its other functionality.

Caution

df = RDataFrame(...)
dl = RDataLoader(...)

ROOT.EnableImplicitMT(2)
dl.save(...)  # RuntimeError

Tip

This scenario is possible:

ROOT.EnableImplicitMT(2)
rdf = RDataFrame(...).Snapshot("t", "f.root")

ROOT.DisableImplicitMT()
df = RDataFrame("t", "f.root")
dl = RDataLoader(df, ...)
dl.save(...)

Checklist:

• tested changes locally

[github-actions]

Test Results

    24 files      24 suites   4d 0h 12m 22s ⏱️
 3 895 tests  3 892 ✅ 0 💤 3 ❌
83 393 runs  83 390 ✅ 0 💤 3 ❌

For more details on these failures, see this check.

Results for commit 4e59624.

♻️ This comment has been updated with latest results.

[vepadulano]

Thanks, this was needed! Let's make sure the CI is not impacted, and see a minor suggestion.