LOG(fatal) is supposed to throw an exception but it never throws because of abort from fclose(stderr)

[YanzhaoW]

Describe the bug

FairRoot/fairtools/FairLogger.cxx

Lines 192 to 203 in fa7108b

	std::cerr << "For later analysis we write a stack trace to " << corefile << std::endl;
	if (freopen(corefile, "w", stderr)) {
	gSystem->StackTrace();
	fclose(stderr);
	}
	}
	throw fair::FatalException("Fatal error occured. Exiting...");
	}

Here the program somehow call the abort when calling fclose(stderr) in the if statement. Therefore, it never reaches to the throwing line.

To Reproduce
Add a printout just above the throw statement and the printout message never gets printed.

Expected behavior
Let it throw

[rbx]

A different idea:
a LOG call should never throw (unless it can't actually log) because of a severity level. It's job is just to make a log entry.
The way it is now is just historical, but it is not good - it is not loggers job to terminate your program. Deprecate/remove it.

If you really want to have a fatal call which throws, call it Fatal() or FATAL macro, which would internally first call LOG, and then throw.

[YanzhaoW]

Yeah, I agree. But would this be a huge breaking change? Many programs would not be terminated in the emergency, which could cause lots of segmentation fault.

[rbx]

I did a quick test with LOG(fatal) at (https://github.com/FairRootGroup/FairRoot/blob/dev/examples/MQ/serialization/data_generator/dataGenerator.cxx#L94) and it throws the exception as expected (which would itself lead to SIGABRT if uncaught).

Could you post a stacktrace to see a bit more detail? Also, what is the corefile filename and does it contain anything meaningful? Perhaps the failure happens there already.

I wonder why the close(stderr) is needed at all. Perhaps it is aborting because it is closed already at that point?