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MDEV-39459 Fix bad sync pattern for chain replication MTR tests#5074

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FarihaIS:mdev-39459
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MDEV-39459 Fix bad sync pattern for chain replication MTR tests#5074
FarihaIS wants to merge 1 commit into
MariaDB:mainfrom
FarihaIS:mdev-39459

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@FarihaIS FarihaIS commented May 13, 2026

Description

In chain replication (1->2->3), several rpl MTR tests synchronize by calling save_master_gtid on server_1 followed by sync_with_master_gtid on server_3, skipping server_2.

This is unsafe because server_2's binlog dump thread can send events to server_3 before commit_ordered() completes on server_2. Any operations on server_2 that depend on the replicated data can then fail intermittently.

Fix by explicitly syncing server_2 before server_3 in all affected tests, and update result files accordingly.

Release Notes

N/A

How can this PR be tested?

Execute the rpl test suite in mysql-test-run:

--------------------------------------------------------------------------
The servers were restarted 559 times
Spent 3203.500 of 545 seconds executing testcases

Completed: All 1230 tests were successful.
83 tests were skipped, 69 by the test itself.

Basing the PR against the correct MariaDB version

  • This is a bug fix, and the PR is based against the main branch.

Copyright

All new code of the whole pull request, including one or several files that are either new files or modified ones, are contributed under the BSD-new license. I am contributing on behalf of my employer Amazon Web Services, Inc.

In chain replication (1->2->3), syncing only server_3 after
save_master_gtid on server_1 does not guarantee server_2 has committed,
because server_2's binlog dump thread can send events to server_3 before
commit_ordered() completes on server_2.

Fix affected rpl tests by syncing server_2 before server_3, and update
result files accordingly.

All new code of the whole pull request, including one or several files
that are either new files or modified ones, are contributed under the
BSD-new license. I am contributing on behalf of my employer Amazon Web
Services, Inc.
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Code Review

This pull request enhances the reliability of replication tests by adding explicit synchronization steps for intermediate servers in chained replication topologies. Specifically, it introduces connections to 'server_2' to sync with 'server_1' and save the GTID state before 'server_3' attempts to synchronize. These changes are applied across multiple test cases and result files to ensure consistent behavior in multi-tier replication environments. I have no feedback to provide as no review comments were included.

@FarihaIS FarihaIS marked this pull request as ready for review May 14, 2026 00:19
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