ToroDB Stampede exposes multiple metrics using JMX, some of them are custom metrics and other are metrics offered by third party products like Flexy-pool.
ToroDB Stampede uses Hikari as a connection pool, but it is wrapped with Flexy-pool, so the metrics exposed by Flexy-pool are available through JMX. So if a JMX console is used the following metrics are available.
|concurrentConnectionsHistogram||A histogram of the number of concurrent connections. This indicates how many connections are being used at once.|
|concurrentConnectionRequestsHistogram||A histogram of the number of concurrent connection requests. This indicates how many connection are being requested at once.|
|connectionAcquireMillis||A time histogram for the target data source connection acquire interval.|
|connectionLeaseMillis||A time histogram for the connection lease time. The lease time is the duration between the moment a connection is acquired and the time it gets released.|
|maxPoolSizeHistogram||A histogram of the target pool size. The pool size might change if the IncrementPoolOnTimeoutConnectionAcquiringStrategy is being used.|
|overallConnectionAcquireMillis||A time histogram for the total connection acquire interval. This is the connectionAcquireMillis plus the time spent by the connection acquire strategies.|
|overflowPoolSizeHistogram||A histogram of the pool size overflowing. The pool size might overflow if the IncrementPoolOnTimeoutConnectionAcquiringStrategy is being used.|
|retryAttemptsHistogram||A histogram of the retry attempts number. This is incremented by the RetryConnectionAcquiringStrategy.|
Because ToroDB Stampede uses more than one connection pool, multiple space names will be avaible through the JMX console.
|com.vladmihalcea.flexypool.metric.codehale.JmxMetricReporter.cursors||Read only connections used by the system.|
|com.vladmihalcea.flexypool.metric.codehale.JmxMetricReporter.session||Connections used by the system to do the replication process from the MongoDB instance.|
|com.vladmihalcea.flexypool.metric.codehale.JmxMetricReporter.system||Connections used by the system to do internal operations.|
More information can be found in this link