Add metrics related to virtual threads #9619
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tjquinno
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ljnelson,
romain-grecourt,
spericas,
barchetta and
tomas-langer
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Some general questions @tjquinno ...
Is there also a counter for platform threads?
Do you have an example?
Under what conditions would this counter be incremented? |
spericas
reviewed
Jan 2, 2025
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| listenFor(rs, Map.of("jdk.VirtualThreadStart", this::recordThreadStart, | ||
| "jdk.VirtualThreadEnd", this::recordThreadEnd)); | ||
| } |
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Should we also track non-virtual thread start/end? Or is that already available elsewhere?
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Description
Resolves #9533
Helidon exposes new meters related to virtual thread usage:
The virtual thread count meters are disabled by default for performance reasons. Enable them by setting
metrics.virtual-threads.count.enabled=truein configuration, but be aware doing so can degrade the server's performance.The PR adds a new
MetersProviderimplementation to thehelidon-metrics-system-meterscomponent. The new implementation registers for selected Java Flight Recorder events to track data related to virtual threads.The three meters enabled by default should be rare so monitoring the JFR events for them adds very little overhead. In contrast, to maintain the current number of active virtual threads and the total number of virtual thread starts the added code must register for and respond to virtual thread start and end events which can be costly. That's why those two meters--and the registration of listeners for those events from JFR--are disabled by default.
Documentation
Small additions to the SE and MP metrics guide and doc pages.