Thread pool and read/write latency statistics

Cassandra maintains distinct thread pools for different stages of execution. Each of the thread pools provide statistics on the number of tasks that are active, pending, and completed. Trends on these pools for increases in the pending tasks column indicate when to add additional capacity. After a baseline is established, configure alarms for any increases above normal in the pending tasks column. Use nodetool tpstats on the command line to view the thread pool details shown in the following table.

Table 1. Compaction Metrics

Thread Pool	Description
AE_SERVICE_STAGE	Shows anti-entropy tasks.
CONSISTENCY-MANAGER	Handles the background consistency checks if they were triggered from the client's consistency level.
FLUSH-SORTER-POOL	Sorts flushes that have been submitted.
FLUSH-WRITER-POOL	Writes the sorted flushes.
GOSSIP_STAGE	Activity of the Gossip protocol on the ring.
LB-OPERATIONS	The number of load balancing operations.
LB-TARGET	Used by nodes leaving the ring.
MEMTABLE-POST-FLUSHER	Memtable flushes that are waiting to be written to the commit log.
MESSAGE-STREAMING-POOL	Streaming operations. Usually triggered by bootstrapping or decommissioning nodes.
MIGRATION_STAGE	Tasks resulting from the call of system_* methods in the API that have modified the schema.
MISC_STAGE
MUTATION_STAGE	API calls that are modifying data.
READ_STAGE	API calls that have read data.
RESPONSE_STAGE	Response tasks from other nodes to message streaming from this node.
STREAM_STAGE	Stream tasks from this node.