celluloid/celluloid — pull request #175 by chuckremes (2013-03-04 23:02:56+00:00)
Title: Better printing of stackdumps in multithreaded environments.

When running multithreaded, several actors might be printing dump messages simultaneously. To prevent the messages from getting comingled to the point of unreadability, build a single string and use #print to print it. A quirk of IO#print is that it is not interruptible so each message printed is completed before another string can be processed.