Limiting Native transport request queue

To limit the max queue size of Native transport requests in Cassandra set below parameter in jvm.options file.

$ cat jvm.options | grep -i native_transport_requests

-Dcassandra.max_queued_native_transport_requests=4096

-Dcassandra.max_queued_native_transport_requests only helps limit the number of blocked threads and in fact will not change active threads at all. In fact it increases the size of the pending queue.

There is another setting that can increase the number of active threads but I have had very limited success it in reducing the number of pending threads: native_transport_max_threads. The default for it is 128.

Reference:

https://issues.apache.org/jira/browse/CASSANDRA-11363

https://support.datastax.com/hc/en-us/articles/360031470531-High-blocked-NTR-count-during-increased-workload-on-Cassandra-node

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