Add "extra info" field to the records
I did this a while back on intel-hpdd's repo, where it seems to have been forgotten.
I have sometimes needed to annotate log fields with extra information. for example, in ROMIO, it was helpful to know which round of two-phase collective I/O an operation happened in.
I suspect EXTRA_INFO would be used rarely, so adding 64 bytes to a log entry all the time seems wasteful. Can switch to a more dynamic approach where EXTRA_INFO allocated only if environment variable set if that seems better