Reverting the Phase-2 HLT menu to not use Tasks

[mmusich]

In #42934 (comment) it was suggested to consider reverting the Phase-2 HLT menu to not use Tasks to avoid triggering undesired unscheduled execution of EDProducers.
The 14_0_X cycle was agreed to be a reasonable target to achieve this (see #42934 (comment)).

[mmusich]

assign hlt

[cmsbuild]

New categories assigned: hlt

@Martin-Grunewald,@mmusich,@missirol you have been requested to review this Pull request/Issue and eventually sign? Thanks

[cmsbuild]

A new Issue was created by @mmusich Marco Musich.

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

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[mmusich]

@rovere @SohamBhattacharya FYI

[makortel]

Just to bring up one option (now that I have some brain bandwidth again), following the discussion in #36938, a ConditionalTask was added in the configuration system. It is similar to Task that it is an unordered collection of EDProducers, but differs such that the ConditionalTask adds the modules in the ConditionalTask to the associated Path in the proper order based on consumes/produces calls of the modules in the Path and in the ConditionalTask. Those modules will then behave as if they were part of the scheduled system (well, in a sense they are), i.e. their execution is dictated only by the EDFilters preceding them in the Path.

There is one caveat though: the modules in ConditionalTask that are not consumed by any other module in the Path, or in the ConditionalTasks associated with the Path, are treated as unscheduled modules (i.e. any other module consuming their data products will cause them to run). Changing the behavior such that those modules would not get run (e.g. by removing them from the job, as is done for any non-consumed unscheduled module already) is in our radar, but we wanted to see first how the ConditionalTask gets used in the HLT (especially if it is still needed after moving from "SwitchProducer with CUDA+legacy modules" towards "module type resolver with Alpaka modules").

If organizing the modules in Task-like way would still be beneficial, maybe it would be worth of trying out ConditionalTask?

[makortel]

#43296 implements the printout of ConditionalTask modules that are not consumed by any module in any of the Paths the ConditionalTask (in question) is associated with, as discussed with some of the HLT folks.

[mmusich]

IIUC #44025 starts to implement things in this direction.

[mmusich]

#44604 completes the migration of the phase-2 HLT menu to use sequences.

[mmusich]

+hlt

• done via Sequence-based simplified HLT phase2 menu. #44025 + Move Muon Paths to use sequences in HLT Phase2 Menu. #44604
• tested in IBs wih no (visible) side effects.

[cmsbuild]

This issue is fully signed and ready to be closed.

[makortel]

@cmsbuild, please close