cassandra.metrics - Performance Metrics¶

class cassandra.metrics.Metrics¶

A collection of timers and counters for various performance metrics.

Timer metrics are represented as floating point seconds.

request_timer = None¶

A PmfStat timer for requests. This is a dict-like object with the following keys:

• count - number of requests that have been timed

• min - min latency

• max - max latency

• mean - mean latency

• stddev - standard deviation for latencies

• median - median latency

• 75percentile - 75th percentile latencies

• 95percentile - 95th percentile latencies

• 98percentile - 98th percentile latencies

• 99percentile - 99th percentile latencies

• 999percentile - 99.9th percentile latencies

connection_errors = None¶

A IntStat count of the number of times that a request to a Cassandra node has failed due to a connection problem.

write_timeouts = None¶

A IntStat count of write requests that resulted in a timeout.

read_timeouts = None¶

A IntStat count of read requests that resulted in a timeout.

unavailables = None¶

A IntStat count of write or read requests that failed due to an insufficient number of replicas being alive to meet the requested ConsistencyLevel.

other_errors = None¶

A IntStat count of all other request failures, including failures caused by invalid requests, bootstrapping nodes, overloaded nodes, etc.

retries = None¶

A IntStat count of the number of times a request was retried based on the RetryPolicy decision.

ignores = None¶

A IntStat count of the number of times a failed request was ignored based on the RetryPolicy decision.

known_hosts = None¶

A IntStat count of the number of nodes in the cluster that the driver is aware of, regardless of whether any connections are opened to those nodes.

connected_to = None¶

A IntStat count of the number of nodes that the driver currently has at least one connection open to.

open_connections = None¶

A IntStat count of the number connections the driver currently has open.

get_stats()¶

Returns the metrics for the registered cluster instance.

set_stats_name(stats_name)¶

Set the metrics stats name. The stats_name is a string used to access the metrics through getStats(): getStats()[<stats_name>] Default is ‘cassandra-<num>’.

shutdown()¶

Remove this metrics instance from the global registry. Called when the cluster is shutdown to prevent stale references.