From the source code, it looks like the CommPort internal lock _R_BUSY is never unlocked for some reason. Most likely, a "background" read is started, followed by another before the first one had a chance to finish (read_done), leading to this message.

This said, I know nothing about serial port handling in Perl, in particular on Win32, so you should probably contact the GPS module author as it looks like a bug in his code.

In reply to Re: Errors in GPS::Serial by waba
in thread Errors in GPS::Serial by deadpickle

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