Catch boost exceptions thrown in FragmentGenerator getNext methods [LArIAT]
Our LArIAT collaborators have noticed that the system sometimes crashes when one of their FragmentGenerators throws a boost exception.
John found that we were only catching cet::exceptions in CommandableFragmentGenerator::getNext() when it called derived class getNext_() methods. He added catch blocks for boost::exception and std::exception. With these changes, the "processing fragments" thread will exit, but the process (and the whole MPI program) will not crash. And, we will get an Error message sent to the Message Facility, and this will help diagnose what happened.