(metrics-jetty9) InstrumentedQueuedThreadPool & InstrumentedHandler don't obey jetty Lifecycle API: can't be restarted (

[hossman]

InstrumentedQueuedThreadPool and InstrumentedHandler do not obey the jetty Lifecycle contract because they can't be stop()ed and restart()ed again later.

This is because they use their configured MetricRegistry to register() metrics in start(), but never remove those registry entries in stop() causing exceptions if the same object is started, stopped, and started again.

(Although I haven't tried using them: InstrumentedHttpChannelListener does not appear to have the same problem, because it only registers metrics in it's constructor. Likewise InstrumentedConnectionFactory doesn't do any Metric registration at all: the caller is required to pass in the Metric objects to be used)