[Flaky Test] `task functions ParallelN [It] should run the tasks`

[ialidzhikov]

How to categorize this issue?

/area testing /kind flake

Which test(s)/suite(s) are flaking: task functions ParallelN [It] should run the tasks

CI link: https://prow.gardener.cloud/view/gs/gardener-prow/pr-logs/pull/gardener_gardener/8912/pull-gardener-unit/1742838404367781888

Reason for failure:

  STEP: Checking active tasks after initial ParallelN call @ 01/04/24 12:18:59.264
  [FAILED] in [It] - /Users/foo/SAPDevelop/go/src/github.com/gardener/gardener/pkg/utils/flow/taskfn_test.go:181 @ 01/04/24 12:19:00.265
  [FAILED] in [AfterEach] - /Users/foo/SAPDevelop/go/pkg/mod/github.com/onsi/ginkgo/v2@v2.13.0/internal/node.go:463 @ 01/04/24 12:19:00.713
  << Timeline

  [FAILED] Timed out after 1.000s.
  Expected
      <int>: 0
  to equal
      <int>: 2
  In [It] at: /Users/foo/SAPDevelop/go/src/github.com/gardener/gardener/pkg/utils/flow/taskfn_test.go:181 @ 01/04/24 12:19:00.265

  There were additional failures detected.  To view them in detail run ginkgo -vv

Anything else we need to know: Steps to reproduce:

# get the stress tool
go install golang.org/x/tools/cmd/stress@latest

# build a test binary
% ./hack/tools/bin/ginkgo build ./pkg/utils/flow
Compiled flow.test

% stress -p 1 ./pkg/utils/flow/flow.test -ginkgo.focus "should run the tasks"
...
3m35s: 1327 runs so far, 85 failures (6.41%)
3m40s: 1351 runs so far, 87 failures (6.44%)
3m45s: 1367 runs so far, 90 failures (6.58%)
3m50s: 1399 runs so far, 92 failures (6.58%)

[ialidzhikov]

Introduced with https://github.com/gardener/gardener/pull/8815.

cc @dimityrmirchev

[dimityrmirchev]

/assign