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Test raft #29

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Test raft #29

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@TaiJuWu TaiJuWu commented Jan 30, 2025

More detailed description of your change,
if necessary. The PR title and PR message become
the squashed commit message, so use a separate
comment to ping reviewers.

Summary of testing strategy (including rationale)
for the feature or bug fix. Unit and/or integration
tests are expected for any behaviour change and
system tests should be considered for larger changes.

Committer Checklist (excluded from commit message)

  • Verify design and implementation
  • Verify test coverage and CI build status
  • Verify documentation (including upgrade notes)

pramithas and others added 15 commits January 30, 2025 12:34
…invocation of close() method with try with resources (apache#18678)

Reviewers: Divij Vaidya <[email protected]>, Greg Harris <[email protected]>, Christo Lolov <[email protected]>
…ncKafkaConsumer (apache#17700)

This change reduces fetch session cache evictions on the broker for AsyncKafkaConsumer by altering its logic to determine which partitions it includes in fetch requests.

Background
Consumer implementations fetch data from the cluster and temporarily buffer it in memory until the user next calls Consumer.poll(). When a fetch request is being generated, partitions that already have buffered data are not included in the fetch request.

The ClassicKafkaConsumer performs much of its fetch logic and network I/O in the application thread. On poll(), if there is any locally-buffered data, the ClassicKafkaConsumer does not fetch any new data and simply returns the buffered data to the user from poll().

On the other hand, the AsyncKafkaConsumer consumer splits its logic and network I/O between two threads, which results in a potential race condition during fetch. The AsyncKafkaConsumer also checks for buffered data on its application thread. If it finds there is none, it signals the background thread to create a fetch request. However, it's possible for the background thread to receive data from a previous fetch and buffer it before the fetch request logic starts. When that occurs, as the background thread creates a new fetch request, it skips any buffered data, which has the unintended result that those partitions get added to the fetch request's "to remove" set. This signals to the broker to remove those partitions from its internal cache.

This issue is technically possible in the ClassicKafkaConsumer too, since the heartbeat thread performs network I/O in addition to the application thread. However, because of the frequency at which the AsyncKafkaConsumer's background thread runs, it is ~100x more likely to happen.

Options
The core decision is: what should the background thread do if it is asked to create a fetch request and it discovers there's buffered data. There were multiple proposals to address this issue in the AsyncKafkaConsumer. Among them are:

The background thread should omit buffered partitions from the fetch request as before (this is the existing behavior)
The background thread should skip the fetch request generation entirely if there are any buffered partitions
The background thread should include buffered partitions in the fetch request, but use a small “max bytes” value
The background thread should skip fetching from the nodes that have buffered partitions
Option 4 won out. The change is localized to AbstractFetch where the basic idea is to skip fetch requests to a given node if that node is the leader for buffered data. By preventing a fetch request from being sent to that node, it won't have any "holes" where the buffered partitions should be.

Reviewers: Lianet Magrans <[email protected]>, Jeff Kim <[email protected]>, Jun Rao <[email protected]>
…rectly (apache#18730)

Fixed the typo that used the wrong producer ID and epoch when returning so that we handle epoch overflow correctly.

We also had to rearrange the concurrent transaction handling so that we don't self-fence when we start the new transaction with the new producer ID.

I also tested this with a modified version of the code where epoch overflow happens on the first epoch bump (every request has a new producer id)

Reviewers: Artem Livshits <[email protected]>, Jeff Kim <[email protected]>
This change implement some of the metrics enumerated in KIP-853.

The KafkaRaftMetrics object now exposes number-of-voters, number-of-observers and uncommitted-voter-change. The number-of-observers and uncommitted-voter-change metrics are only present on the active controller or leader, since it does not make sense for other replicas to report these metrics.

In order to make these two metrics thread-safe, KafkaRaftMetrics needs to be passed into LeaderState, and therefore QuorumState. This introduces a circularity since the KafkaRaftMetrics constructor takes in QuorumState. To break the circularity for now, the logic using QuorumState will be moved to the KafkaRaftMetrics#initialize method.

The BrokerServerMetrics object now exposes ignored-static-voters. The ControllerServerMetrics object now exposes IgnoredStaticVoters. To implement both metrics for "ignored static voters", this PR introduces the ExternalKRaftMetrics interface, which allows for higher layer metrics objects to be accessible within the raft module.

Reviewers: José Armando García Sancio <[email protected]>
This patch converts the ConsoleConsumerTest system test to only use KRaft.

Reviewers: David Jacot <[email protected]>
…e-added as KRaft (apache#18766)

This patch renames kraft_upgrade_test.py to upgrade_test.py. This is enough to cover the old upgrade/downgrade tests.

Reviewers: Chia-Ping Tsai <[email protected]>
@TaiJuWu TaiJuWu force-pushed the test_raft branch 3 times, most recently from 16c54eb to 5fb6ef5 Compare January 31, 2025 15:14
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