Norman,

   Thanks for this, and also thanks to Cedric for the "unofficial" guide. Related to my original inquiry, I read that the log function "relies on a fair bit of framework infrastructure such as synchronization primitives," and I became curious if calling "log" as a debugging message from within an IO signal handler is possibly the source of my problem? This is supported by my having given up on the warning message and disabled the debug messages, only to see the warning message disappear. I am still doubtful that it is the true cause - I think that it's more likely that the shorter signal handler with no logging simply doesn't have time to trigger the bad behavior very often - but I became concerned that if indeed "log" is a problem if called during a signal handler, then my entire debugging strategy needs to be revisited. So it is worth asking someone who understands the signaling and IPC better than I do if log is OK during an IO signal handler (i.e. that log will not allow any other signal handlers to run)?

Regards,