Compare Instana Node.js collector vs. OpenTelemetry JavaScript instrumentation library for runtime metrics

[morningspace]

For runtime metrics, Instana has its own implementation, which is different from the OpenTelemetry implementation.

This issue is to track the difference, including:

• The different runtime metrics being collected by the two libraries.
• The different ways being used to collect the runtime metrics.

The final goal is:

• Build the integration package (the custom dashboards) for node.js runtime based on the combined view of the two runtime metrics sets.
• Identify the gap between the two implementations. For those that are missed in the OpenTelemetry implementation, see if we can contribute back to the community.

[morningspace]

The OpenTelemetry Node.js runtime instrumentation implementation can be found at:
https://github.com/open-telemetry/opentelemetry-js-contrib/blob/main/plugins/node/instrumentation-runtime-node/README.md

[liyanwei93]

Metircs in Instana Nodejs

Metrics Name	Description	Unit	Retrieval Method
gc.gcPause	GC Pause	MILLIS	stats.end - stats.start (nativeModuleName: 'gcstats.js')
gc.minorGcs	Minor GCs	NUMBER	stats.gctype (nativeModuleName: 'gcstats.js')
gc.majorGcs	Major GCs	NUMBER	stats.gctype (nativeModuleName: 'gcstats.js')
gc.usedHeapSizeAfterGc	Heap Size After GC	BYTES	stats.after.usedHeapSize (nativeModuleName: 'gcstats.js')
activeHandles	Handles	NUMBER	process._getActiveHandles
activeRequests	Requests	NUMBER	process._getActiveRequests
memory.rss	RSS	BYTES	process.memoryUsage.rss
memory.heapUsed	Heap Size	BYTES	process.memoryUsage.heapUsed
libuv.max	Longest time in single loop	MILLIS	eventLoopStats.sense() (nativeModuleName: 'event-loop-stats')
libuv.sum	Total time in loop	MILLIS	eventLoopStats.sense() (nativeModuleName: 'event-loop-stats')
libuv.lag	Event loop lag	MILLIS	eventLoopStats.sense() (nativeModuleName: 'event-loop-stats')
libuv.num	Loops per second	NUMBER	eventLoopStats.sense() (nativeModuleName: 'event-loop-stats')
heapSpaces.used	Heap Spaces Used	BYTES	v8.getHeapSpaceStatistics().space_used_size
heapSpaces.available	Heap Spaces Available	BYTES	v8.getHeapSpaceStatistics().space_available_size
heapSpaces.current	Heap Spaces Current	BYTES	v8.getHeapSpaceStatistics().space_size
heapSpaces.physical	Heap Spaces Physical	BYTES	v8.getHeapSpaceStatistics().physical_space_size

Metircs in opentelemetry Nodejs with @opentelemetry/instrumentation-runtime-node

Metrics Name	Description	Unit	Retrieval Method
v8js.gc.duration{v8js.gc.type="minor"}	Garbage collection duration by kind, one of major, minor, incremental, or weakcb	N/A	perf_hooks.PerformanceObserver
nodejs.eventloop.delay.max	Event loop maximum delay	N/A	perf_hooks.monitorEventLoopDelay.histogram.max
nodejs.eventloop.delay.mean	Event loop mean delay	N/A	perf_hooks.monitorEventLoopDelay.histogram.mean
nodejs.eventloop.delay.min	Event loop minimum delay	N/A	perf_hooks.monitorEventLoopDelay.histogram.min
nodejs.eventloop.delay.p50	Event loop 50th percentile delay	N/A	perf_hooks.monitorEventLoopDelay.histogram.percentile(50)
nodejs.eventloop.delay.p90	Event loop 90th percentile delay	N/A	perf_hooks.monitorEventLoopDelay.histogram.percentile(90)
nodejs.eventloop.delay.p99	Event loop 99th percentile delay	N/A	perf_hooks.monitorEventLoopDelay.histogram.percentile(99)
nodejs.eventloop.delay.stddev	Event loop standard deviation delay	N/A	perf_hooks.monitorEventLoopDelay.histogram.stddev
nodejs.eventloop.time	Cumulative duration of time the event loop has been in each state	N/A	perf_hooks.eventLoopUtilizationCollector.active & idle
nodejs.eventloop.utilization	Event loop utilization	N/A	perf_hooks.eventLoopUtilizationCollector._lastValue.utilization
v8js.memory.heap.limit{v8js.heap.space.name}	Total heap memory size pre-allocated	N/A	v8.getHeapSpaceStatistics().space_size
v8js.memory.heap.space.available_size{v8js.heap.space.name}	Heap space available size	N/A	v8.getHeapSpaceStatistics().space_available_size
v8js.memory.heap.space.physical_size{v8js.heap.space.name}	Committed size of a heap space.	N/A	v8.getHeapSpaceStatistics().physical_space_size
v8js.memory.heap.used{v8js.heap.space.name}	Heap memory size allocated	N/A	v8.getHeapSpaceStatistics().space_used_size

Summary

libuv.max ≈ nodejs.eventloop.delay.max: Max loop time/delay
libuv.sum ≈ nodejs.eventloop.time: Cumulative time in the event loop
libuv.lag ≈ nodejs.eventloop.delay.mean: Average delay

heapSpaces.used ≈ v8js.memory.heap.used
heapSpaces.available ≈ v8js.memory.heap.space.available_size
heapSpaces.current ≈ v8js.memory.heap.limit
heapSpaces.physical ≈ v8js.memory.heap.space.physical_size