DEBUG-3175 DI snapshot/rate limit benchmark

[p-datadog]

What does this PR do?

Adds dynamic instrumentation benchmarks verifying that the rate at which probes can capture, serialize and submit snapshots to the agent are below the rate limits.

It also makes the probe notifier worker queue capacity configurable via an internal setting. With default DI settings, DI will permit no more than 30 snapshots/second on average across all probes which is well short of the 5000/second/probe that this benchmark is aiming to achieve. The benchmark raises the limit (and makes flushes more frequent) to demonstrate theoretical performance of DI implementation, however more work is needed to permit higher limits by default - flushing logic must be carefully written to not starve the application of CPU. The default limits are very conservative in this regard.

Motivation:

We want to ensure that the rate limits we set are achievable, meaning they are not set so high that DI code can starve customer applications of CPU and still not hit rate limits.

Change log entry

None.

Additional Notes:

The benchmarks perform as many invocations of target methods as each probe type would permit (5000/second for basic probes, 1/second for enriched probes). A rate of greater than 1 instruction/second in the benchmark means the rate limit was not reached by the test code and thus DI performance is within expectations.

How to test the change?

N/A

[github-actions]

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^{Visited at: 2024-12-09 21:35:47 UTC}

[pr-commenter]

Benchmarks

Benchmark execution time: 2024-12-18 06:15:12

Comparing candidate commit fda26e8 in PR branch di-rate-limit-benchmark with baseline commit c07a8d4 in branch master.

Found 0 performance improvements and 1 performance regressions! Performance is the same for 30 metrics, 2 unstable metrics.

scenario:profiler - sample timeline=false

• 🟥 throughput [-0.550op/s; -0.541op/s] or [-8.340%; -8.216%]

[codecov-commenter]

Codecov Report

Attention: Patch coverage is 93.33333% with 1 line in your changes missing coverage. Please review.

Project coverage is 97.77%. Comparing base (c07a8d4) to head (fda26e8).
Report is 104 commits behind head on master.

Files with missing lines	Patch %	Lines
spec/datadog/di/validate_benchmarks_spec.rb	88.88%	1 Missing ⚠️

Additional details and impacted files

@@           Coverage Diff           @@
##           master    #4207   +/-   ##
=======================================
  Coverage   97.77%   97.77%           
=======================================
  Files        1357     1357           
  Lines       81973    81983   +10     
  Branches     4168     4170    +2     
=======================================
+ Hits        80145    80162   +17     
+ Misses       1828     1821    -7     

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[datadog-datadog-prod-us1]

Datadog Report

Branch report: di-rate-limit-benchmark
Commit report: fda26e8
Test service: dd-trace-rb

✅ 0 Failed, 22237 Passed, 1458 Skipped, 5m 58.82s Total Time