Speed up tests locally by upto 45%

[anshgoyalevil]

Which problem is this PR solving?

• This PR aims to add an additional flag to the jest script which would make running tests locally even faster than ever.

Description of the changes

• It uses --maxWorkers=50% flag to do so.

How was this change tested?

• It was tested with several flags as below;

-----------------
yarn test

Time:        96.903 s
-----------------
yarn test --runInBand

Time:        131.721 s, estimated 606 s
-----------------
yarn test --maxWorkers=50%

Time:        53.295 s
-----------------

Operating System Used to Benchmark:
Ubuntu 22

Checklist

• I have read https://github.com/jaegertracing/jaeger/blob/master/CONTRIBUTING_GUIDELINES.md
• I have signed all commits
• I have added unit tests for the new functionality
• I have run lint and test steps successfully
  • for jaeger: make lint test
  • for jaeger-ui: yarn lint and yarn test

[codecov]

Codecov Report

Patch has no changes to coverable lines.

📢 Thoughts on this report? Let us know!.

[yurishkuro]

does % refer to the number of available CPU cores?

[anshgoyalevil]

Yes. It's the CPU Cores present in the current run environment. Most of the articles on internet recommends this setting.

[yurishkuro]

Makes sense for local testing, so as not to bring the whole system down during the test. But if this %-based addressing scheme is available, why does the line below have --maxWorkers=4? We don't really know how many CPU cores are available in a CI runner, but it would make sense to utilize all of them.

[anshgoyalevil]

Every CI environment has their own workers limit, and the setting which we are currently using for test-ci is adapted to GitHub Actions only.

Moreover, reason for choosing a concrete value (4) instead of % over here is because in CI, we know we won't be performing multi-tasking, so all threads can be used for tests. (Minus the thread for main workflow task)

In future, if we have any plans to move to another CI environment like CircleCI, I think we would again have to figure out this max number of workers. (I guess, it's 8 for CircleCI).

[yurishkuro]

But why can't we say 100% for GitHub? When the tests are running, no other activity is higher priority.

[anshgoyalevil]

Theoretically that seems right. Don't know why everyone suggests using a number value instead of percentage in CI for jest.

I would have to try that thing.