When upgrading from 2.1.9 to 2.1.13, we are witnessing an issue where the machine load increases to very high levels (> 120 on an 8 core machine) and native transport requests get blocked in tpstats.
I was able to reproduce this in both CMS and G1GC as well as on JVM 7 and 8.
The issue does not seem to affect the nodes running 2.1.9.
The issue seems to coincide with the number of connections OR the number of total requests being processed at a given time (as the latter increases with the former in our system)
Currently there is between 600 and 800 client connections on each machine and each machine is handling roughly 2000-3000 client requests per second.
Disabling the binary protocol fixes the issue for this node but isn't a viable option cluster-wide.
Here is the output from tpstats:
Attached is the jstack output for both CMS and G1GC.
It is interesting to note that while the flight recording was taking place, the load on the machine went back to healthy, and when the flight recording finished the load went back to > 100.