THIS IS A TEST INSTANCE. ALL YOUR CHANGES WILL BE LOST!!!!
Please keep the discussion on the mailing list rather than commenting on the wiki (wiki discussions get unwieldy fast).
Motivation
Flink currently exposes the following GC related metrics:
| Job-/TaskManager | Status.JVM.GarbageCollector | <GarbageCollector>.Count | The total number of collections that have occurred. | Gauge |
|---|---|---|---|---|
| <GarbageCollector>.Time | The total time spent performing garbage collection. | Gauge |
Unfortunately these are not very useful for monitoring purposes as they require post processing logic that is also dependent on the current runtime environment:
- Total time is not very relevant for long running applications, only the rate of change (millisPerSec or similar)
- In most cases it's best to simply aggregate the time/count across the different GabrageCollectors, however the specific collectors are dependent on the current Java runtime
- It's impossible to detect long GC pauses that may cause heartbeat timeouts
We propose to improve the current situation by:
- Exposing rate metrics per GarbageCollector
- Exposing aggregated Total time/count/rate metrics
- Expose average GC time metric in the current measurement window (last 1 minute)
These new metrics are all derived from the existing ones with minimal overhead.
Public Interfaces / Proposed Changes
New GC metrics (in addition to the existing ones)
| Job-/TaskManager | Status.JVM.GarbageCollector | <GarbageCollector>.TimeMsPerSec | Milliseconds spent performing garbage collection per second. | Meter |
|---|---|---|---|---|
| <GarbageCollector>.AverageTime | Average collection time in the current metric window. Delta(Time) / Delta(Count) | Gauge | ||
| All.Time | The total time spent performing garbage collection across all collectors. | Gauge | ||
| All.TimeMsPerSec | Milliseconds spent performing garbage collection per second across all collectors. | Meter | ||
| All.AverageTime | Average collection time in the current metric window across all collectors. Delta(Time) / Delta(Count) | Gauge | ||
| All.Count | The total number of collections that have occurred across all collectors. | Gauge |
Compatibility, Deprecation, and Migration Plan
These are new metrics, no user impact.