[fix][test] Fix flaky PrometheusMetricsTest.testBrokerMetrics

[pdolif]

Fixes #24041

Motivation

The test contains the following assertion:

assertEquals(systemCursorOutBytes, systemInBytes)

systemInBytes is set to the value of the pulsar_broker_in_bytes_total metric for the system topic.

systemCursorOutBytes is currently set to the value of

• pulsar_out_bytes_total of the system reader subscription or
• pulsar_out_bytes_total of the compaction subscription.

The pulsar_out_bytes_total metric is always present for both the system reader and compaction subscription, but the order is not deterministic. Therefore, it happens that instead of setting systemCursorOutBytes to pulsar_out_bytes_total for the system reader subscription, it is set to pulsar_out_bytes_total of the compaction subscription (which always seems to be 0).

double systemCursorOutBytes = 0.0;
for (Metric metric : topicLevelBytesOutTotal) {
    if (metric.tags.get("subscription").startsWith(SystemTopicNames.SYSTEM_READER_PREFIX)
            || metric.tags.get("subscription").equals(Compactor.COMPACTION_SUBSCRIPTION)) {
        systemCursorOutBytes = metric.value;
    }
}

Modifications

Remove the metric.tags.get("subscription").equals(Compactor.COMPACTION_SUBSCRIPTION) case.

Verifying this change

• Make sure that the change passes the CI checks.

Does this pull request potentially affect one of the following parts:

If the box was checked, please highlight the changes

• Dependencies (add or upgrade a dependency)
• The public API
• The schema
• The default values of configurations
• The threading model
• The binary protocol
• The REST endpoints
• The admin CLI options
• The metrics
• Anything that affects deployment

Documentation

• doc
• doc-required
• doc-not-needed
• doc-complete

Matching PR in forked repository

PR in forked repository: pdolif#8

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 74.36%. Comparing base (bbc6224) to head (3aac8f4).
Report is 1090 commits behind head on master.

Additional details and impacted files

@@             Coverage Diff              @@
##             master   #24042      +/-   ##
============================================
+ Coverage     73.57%   74.36%   +0.78%     
+ Complexity    32624     2379   -30245     
============================================
  Files          1877     1861      -16     
  Lines        139502   144804    +5302     
  Branches      15299    16538    +1239     
============================================
+ Hits         102638   107679    +5041     
+ Misses        28908    28678     -230     
- Partials       7956     8447     +491     

Flag	Coverage Δ
inttests	26.73% <ø> (+2.15%)	⬆️
systests	23.09% <ø> (-1.23%)	⬇️
unittests	73.87% <ø> (+1.02%)	⬆️

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see 1059 files with indirect coverage changes

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[lhotari]

LGTM, great job @pdolif