Use MessageSvc to handle ROOT messages

The default ROOT error handler (the equivalent of Gaudi MessageSvc) prints messages to stderr, which is problematic with Gaudi based workflows that expect all messages to go through stdout and be filtered according to MessageSvc output level.

This MR replaces the ROOT error handler with an adapter function that redirects to MessageSvc.

There are a couple of drawbacks which the changes proposed here:

• it works only if ROOT (gROOT) has been initialized before ApplicationMgr::configure, but my tests suggest this is always the case
• every message sent by ROOT makes a call to IMessageSvc::outputLevel( source ) to decide if the message has to be printed or not, while MsgStream instances cache the thresholds; we can optimize the adapter caching internally the thresholds (e.g. with a static std::unordered_map<std::string, int> thresholds) or by using a global threshold for ROOT messages.

changed milestone to %v36r10

added lhcb-gaudi-head lhcb-head-2 labels

@sponce, this is what we were discussing this morning.

added 1 commit

• d1fec076 - Update test reference files

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how does this interact with when root tries to do a stack trace during a core dump?

It's an excellent question. ROOT does not use the error handler to print the stack trace, so it works as usual.

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• c32e889b - Update test reference files

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• [2023-01-21 00:03] Validation started with lhcb-gaudi-head#3452
• [2023-01-21 00:23] Validation started with lhcb-run2-gaudi-head#442
• [2023-01-23 00:03] Validation started with lhcb-gaudi-head#3453

mentioned in merge request lhcb/LHCb!3938 (closed)

mentioned in merge request lhcb/LHCb!3939 (closed)

added 2 commits

• 16582dfb - Allow disabling use of MessageSvc for ROOT
• 0768b104 - Restore original ROOT error handler at terminate

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resolved all threads

added 2 commits

• 5cd6a7df - Allow disabling use of MessageSvc for ROOT
• aad0e7e5 - Restore original ROOT error handler at terminate

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added 1 commit

• 2d7f3471 - Restore original ROOT error handler at terminate

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resolved all threads

added 2 commits

• 22723973 - Allow disabling use of MessageSvc for ROOT
• 003faa12 - Restore original ROOT error handler at terminate

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• [2023-01-24 00:04] Validation started with lhcb-gaudi-head#3454
• [2023-01-24 00:13] Validation started with lhcb-run2-gaudi-head#443
• [2023-01-25 00:03] Validation started with lhcb-gaudi-head#3455
• [2023-01-25 00:11] Validation started with lhcb-run2-gaudi-head#444
• [2023-01-26 00:04] Validation started with lhcb-gaudi-head#3456
• [2023-01-26 00:16] Validation started with lhcb-run2-gaudi-head#445

There is definitely some fallout from this on the ATLAS side. We are now starting to see warning messages from TClass that were previously suppressed. Likely that's related to our use of gErrorIgnoreLevel that is now being ignored. But I need to look more closely to be sure.

added 1 commit

• be086a4c - Take into account ROOT message suppression in ROOTErrorHandlerAdapter

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resolved all threads

resolved all threads

About the default setting, the main reason why I started this exercise is that ROOT prints all messages to stderr, and in 6.26 we are getting a new Info message that we cannot avoid and it's causing our tests to fail in a way that is a bit tricky to hide. Redirecting the messages to stdout is a good workaround for us and the easiest way was to override the ROOT error handler.

I'd like to keep the default to go to MessageSvc, but we can discuss.

mentioned in merge request atlas/athena!60061 (merged)

approved this merge request

Looks good from the ATLAS side now.

merged

mentioned in commit 0069c7e8

mentioned in merge request atlas/athena!60753 (merged)