As part of LU-2827 patch intensive testing, J.Simmons encountered a new issue when running with patch on top of latest/current 2.5.59/master version.
Having a look to the infos provided (ftp.whamcloud.com/uploads/LU-4584/20140609-run1.tbz and 20140609-run2.tbz), it appears that at some point of time, Client's RPCs are not sent anymore. This mainly causes Client's locks cancel answers to Server's/OSTs blocking ASTs requests not to be sent and further evictions.
The reason why Client's RPCs are not sent anymore can not be found using only the Lustre debug log level (dlmtrace) on Client, but I can see during Client's eviction process/handling these RPCs were on the delayed queue.