add runtime.node.event_loop.utilization metric

[tlhunter]

What does this PR do?

• adds a new metric based on event loop utilization
• this value is between 0 (idle) and 1 (busy)
• tracks the overall utilization for a given 10 second period
• available as runtime.node.event_loop.utilization

Motivation

• the metric is a straightforward way to tell how busy a Node.js process is

Plugin Checklist

• Unit tests.
• TypeScript definitions.
• TypeScript tests.
• API documentation.
• CircleCI jobs/workflows.
• Plugin is exported.

Additional Notes

• this originated as a customer request

[github-actions]

Overall package size

Self size: 3.83 MB
Deduped: 57.47 MB
No deduping: 57.51 MB

Dependency sizes

name	version	self size	total size
@datadog/native-iast-taint-tracking	1.1.1	13.38 MB	13.39 MB
@datadog/native-appsec	2.0.0	12.33 MB	12.34 MB
@datadog/pprof	2.0.0	10.47 MB	11.35 MB
@datadog/native-metrics	1.5.0	7.1 MB	7.11 MB
protobufjs	7.1.2	2.76 MB	6.55 MB
@datadog/native-iast-rewriter	1.1.2	2.06 MB	2.08 MB
opentracing	0.14.7	194.81 kB	194.81 kB
@datadog/sketches-js	2.1.0	109.9 kB	109.9 kB
lodash.sortby	4.7.0	75.76 kB	75.76 kB
lru-cache	7.14.0	74.95 kB	74.95 kB
semver	5.7.1	61.58 kB	61.58 kB
ipaddr.js	2.0.1	59.52 kB	59.52 kB
ignore	5.2.0	48.87 kB	48.87 kB
import-in-the-middle	1.3.4	32.7 kB	37.17 kB
istanbul-lib-coverage	3.2.0	29.34 kB	29.34 kB
retry	0.10.1	27.44 kB	27.44 kB
lodash.uniq	4.5.0	25.01 kB	25.01 kB
limiter	1.1.5	23.17 kB	23.17 kB
lodash.kebabcase	4.1.1	17.75 kB	17.75 kB
lodash.pick	4.4.0	16.33 kB	16.33 kB
node-abort-controller	3.0.1	14.33 kB	14.33 kB
crypto-randomuuid	1.0.0	11.18 kB	11.18 kB
diagnostics_channel	1.1.0	7.07 kB	7.07 kB
path-to-regexp	0.1.7	6.78 kB	6.78 kB
koalas	1.0.2	6.47 kB	6.47 kB
methods	1.1.2	5.29 kB	5.29 kB
module-details-from-path	1.0.3	4.47 kB	4.47 kB

_{🤖 This report was automatically generated by heaviest-objects-in-the-universe}

[codecov]

Codecov Report

Merging #2846 (90550cd) into master (763009e) will increase coverage by 0.03%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##           master    #2846      +/-   ##
==========================================
+ Coverage   89.16%   89.19%   +0.03%     
==========================================
  Files         317      317              
  Lines       11300    11305       +5     
  Branches       33       33              
==========================================
+ Hits        10076    10084       +8     
+ Misses       1224     1221       -3     

Impacted Files	Coverage Δ
packages/dd-trace/src/metrics.js	78.91% <100.00%> (+0.65%)	⬆️
packages/dd-trace/src/telemetry/dependencies.js	100.00% <0.00%> (+1.81%)	⬆️
packages/dd-trace/src/telemetry/index.js	94.54% <0.00%> (+3.63%)	⬆️

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[pr-commenter]

Benchmarks

Comparing candidate commit 90550cd in PR branch tlhunter/event-loop-utilization with baseline commit 763009e in branch master.

Found 0 performance improvements and 0 performance regressions! Performance is the same for 742 metrics, 200 unstable metrics.

[theJC]

Can #2533 be closed out then?