[v22.2.x] ducktape: partition_balancer test_full_nodes calculate messages amount

[BenPope]

Backport of PR #6832 (cherry picked from commit 50d8d684c1ff165a729162c71631e029cd86e71f)

Due to similar failure on v22.2.x https://buildkite.com/redpanda/redpanda/builds/18749#018482e2-eb8b-4909-990c-6a2489d247dd

UX Changes

• none

Release Notes

• none

[BenPope]

CI Failure is:

Module: rptest.tests.partition_balancer_test
Class:  PartitionBalancerTest
Method: test_full_nodes

Log:

[INFO  - 2022-11-17 11:31:40,976 - runner_client - log - lineno:278]: RunnerClient: rptest.tests.partition_balancer_test.PartitionBalancerTest.test_full_nodes: FAIL: ValueError('max_workers must be greater than 0')
Traceback (most recent call last):
  File "/usr/local/lib/python3.10/dist-packages/ducktape/tests/runner_client.py", line 135, in run
    data = self.run_test()
  File "/usr/local/lib/python3.10/dist-packages/ducktape/tests/runner_client.py", line 227, in run_test
    return self.test_context.function(self.test)
  File "/root/tests/rptest/services/cluster.py", line 52, in wrapped
    self.redpanda.trim_logs()
  File "/root/tests/rptest/services/redpanda.py", line 1517, in trim_logs
    self._for_nodes(self.nodes, prune, parallel=True)
  File "/root/tests/rptest/services/redpanda.py", line 737, in _for_nodes
    with concurrent.futures.ThreadPoolExecutor(
  File "/usr/lib/python3.10/concurrent/futures/thread.py", line 144, in __init__
    raise ValueError("max_workers must be greater than 0")
ValueError: max_workers must be greater than 0

Which this PR was supposed to fix. So that's unfortunate.

[ZeDRoman]

Which this PR was supposed to fix. So that's unfortunate.

This error is not connected with one that I was fixing.

I think that we need to wait backporting fix for this comment https://github.com/redpanda-data/redpanda/issues/6810#issuecomment-1282460897

[BenPope]

Which this PR was supposed to fix. So that's unfortunate.

This error is not connected with one that I was fixing.

I think that we need to wait backporting fix for this comment #6810 (comment)

That one (https://github.com/redpanda-data/redpanda/pull/7344) is merged, isn't it?

[ztlpn]

#6757 (and its backport #7344) introduces the bug, not fixes it :)

[ztlpn]

The fix is #6814 (backported in #7389)

[andrwng]

I'm not sure I follow what was merged here and what wasn't, but I think I hit the issue reported on v22.2.x:

https://buildkite.com/redpanda/redpanda/builds/22776#01863183-571a-42e3-9461-403e43a11e74

[dlex]

Me too (v22.2.x, amd64 VM): https://buildkite.com/redpanda/redpanda/builds/22883#0186372a-cf68-4cb9-a10f-9dcb31890b8a