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Let IMT influence TThreadedObject #1019

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xvallspl wants to merge 1 commit into from
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Let IMT influence TThreadedObject #1019

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8 changes: 7 additions & 1 deletion core/thread/inc/ROOT/TThreadedObject.hxx
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Original file line number Diff line number Diff line change
Expand Up @@ -153,12 +153,18 @@ namespace ROOT {
/// objects.
/// \tparam ARGS Arguments of the constructor of T
template<class ...ARGS>
TThreadedObject(ARGS&&... args): fObjPointers(fgMaxSlots, nullptr)
TThreadedObject(ARGS&&... args)
{
fDirectories = Internal::TThreadedObjectUtils::DirCreator<T>::Create(fgMaxSlots);

TDirectory::TContext ctxt(fDirectories[0]);
fModel.reset(Internal::TThreadedObjectUtils::Detacher<T>::Detach(new T(std::forward<ARGS>(args)...)));

if(ROOT::IsImplicitMTEnabled()) {
TThreadedObject<T>::fgMaxSlots = ROOT::GetImplicitMTPoolSize();
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@pcanal pcanal Sep 19, 2017

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Why change the value for each TThreadObject creation?

Also, in order for this line (and the next) to be thread safe fgMaxSlots needs to be an std::atomic. [Otherwise, per the standard, the behavior when the reading (line 167) and the writing (line 164) happen at the 'same time' is undefined]

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@xvallspl xvallspl Sep 19, 2017

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Good point. Will look into it 🤔

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@eguiraud eguiraud Sep 20, 2017 •
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@pcanal doesn't everything go bonkers anyway if users call EnableImplicitMT in a thread while they are using implicit-mt-aware features in other threads concurrently?

In other words, shouldn't EnableImplicitMT be called strictly before doing anything that checks whether implicit-mt is enabled or not?

}

fObjPointers.resize(fgMaxSlots, nullptr);
}

/// Access a particular processing slot. This
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