add event loop and gc configuration for runtime metrics

[rochdev]

What does this PR do?

Add event loop and GC configuration for runtime metrics.

Motivation

Allow finer control on the types of metrics to collect, especially on the native front. Allowing to pick which GC collector to use can also be used to work around issues with one of the collector by temporarily switching to a different one.

[github-actions]

Overall package size

Self size: 9.72 MB
Deduped: 106.23 MB
No deduping: 106.74 MB

Dependency sizes

| name | version | self size | total size | |------|---------|-----------|------------| | @datadog/libdatadog | 0.7.0 | 35.02 MB | 35.02 MB | | @datadog/native-appsec | 8.5.2 | 19.33 MB | 19.34 MB | | @datadog/native-iast-taint-tracking | 4.0.0 | 11.72 MB | 11.73 MB | | @datadog/pprof | 5.8.2 | 9.56 MB | 9.93 MB | | @opentelemetry/core | 1.30.1 | 908.66 kB | 7.16 MB | | protobufjs | 7.5.3 | 2.95 MB | 5.6 MB | | @datadog/wasm-js-rewriter | 4.0.1 | 2.85 MB | 3.58 MB | | @datadog/native-metrics | 3.1.1 | 1.02 MB | 1.43 MB | | @opentelemetry/api | 1.8.0 | 1.21 MB | 1.21 MB | | import-in-the-middle | 1.14.0 | 120.58 kB | 841.68 kB | | source-map | 0.7.4 | 226 kB | 226 kB | | opentracing | 0.14.7 | 194.81 kB | 194.81 kB | | lru-cache | 7.18.3 | 133.92 kB | 133.92 kB | | pprof-format | 2.1.0 | 111.69 kB | 111.69 kB | | @datadog/sketches-js | 2.1.1 | 109.9 kB | 109.9 kB | | lodash.sortby | 4.7.0 | 75.76 kB | 75.76 kB | | ignore | 5.3.2 | 53.63 kB | 53.63 kB | | istanbul-lib-coverage | 3.2.2 | 34.37 kB | 34.37 kB | | rfdc | 1.4.1 | 27.15 kB | 27.15 kB | | @isaacs/ttlcache | 1.4.1 | 25.2 kB | 25.2 kB | | dc-polyfill | 0.1.9 | 25.11 kB | 25.11 kB | | tlhunter-sorted-set | 0.1.0 | 24.94 kB | 24.94 kB | | shell-quote | 1.8.2 | 23.54 kB | 23.54 kB | | limiter | 1.1.5 | 23.17 kB | 23.17 kB | | retry | 0.13.1 | 18.85 kB | 18.85 kB | | semifies | 1.0.0 | 15.84 kB | 15.84 kB | | jest-docblock | 29.7.0 | 8.99 kB | 12.76 kB | | crypto-randomuuid | 1.0.0 | 11.18 kB | 11.18 kB | | ttl-set | 1.0.0 | 4.61 kB | 9.69 kB | | mutexify | 1.4.0 | 5.71 kB | 8.74 kB | | path-to-regexp | 0.1.12 | 6.6 kB | 6.6 kB | | koalas | 1.0.2 | 6.47 kB | 6.47 kB | | module-details-from-path | 1.0.4 | 3.96 kB | 3.96 kB |

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

[codecov]

Codecov Report

Attention: Patch coverage is 87.50000% with 4 lines in your changes missing coverage. Please review.

Project coverage is 80.75%. Comparing base (a408cd7) to head (ca81a0f).

Files with missing lines	Patch %	Lines
...es/dd-trace/src/runtime_metrics/runtime_metrics.js	73.33%	4 Missing ⚠️

Additional details and impacted files

@@           Coverage Diff           @@
##           master    #5913   +/-   ##
=======================================
  Coverage   80.75%   80.75%           
=======================================
  Files         462      462           
  Lines       19924    19941   +17     
=======================================
+ Hits        16090    16104   +14     
- Misses       3834     3837    +3     

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[datadog-datadog-prod-us1]

Datadog Report

Branch report: runtime-metrics-gc-loop-config
Commit report: 9a55f16
Test service: dd-trace-js-integration-tests

✅ 0 Failed, 1255 Passed, 0 Skipped, 20m 35.9s Total Time

[pr-commenter]

Benchmarks

Benchmark execution time: 2025-06-19 15:51:13

Comparing candidate commit ca81a0f in PR branch runtime-metrics-gc-loop-config with baseline commit a408cd7 in branch master.

Found 0 performance improvements and 0 performance regressions! Performance is the same for 1265 metrics, 58 unstable metrics.

[szegedi]

Does it make sense to have these as two separate config properties? You could have just one (just keep .gc?) and introduce an 'off' value (and maybe use 'on' instead of 'default' for consistency.) You could still have config translate incoming env var values of '0', '1', 'true', 'false' to off and on. Of course, for consistency you should then probably allow use of off and on as keywords for the other two properties a well (enabled and eventLoop.) Maybe we should just add on and off as recognized values in util.js.

We recently added a config for choosing the compression method for uploading profiles and use on/off there in addition to specifically naming compression methods.

Of course, if you envision there could be even more config options for GC metrics in the future, then it may make sense to keep them as separate properties, but we should assess how likely is that.