Details
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Bug
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Status: In Review (View Workflow)
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Critical
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Resolution: Unresolved
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13.0
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Can result in hang or crash
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Q3/2026 Server Development
Description
A test that is being introduced by MDEV-39061 would time out due to an infinite loop. Initially, I was unable to reproduce it on my system. Adding more concurrency helped to delay a log checkpoint sufficiently:
MTR_TESTCASE_TIMEOUT=1 mysql-test/mtr --repeat=15 --parallel=40 mariabackup.huge_lsn,SERVER,strict_full_crc32{,,,,,,,}{,,,,} |
This would allow the test to fail in my development environment, where nproc reports 24:
mariabackup.huge_lsn 'SERVER,strict_full_crc32' w20 [ 9 pass ] 13969
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mariabackup.huge_lsn 'SERVER,strict_full_crc32' w3 [ 8 pass ] 14219
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mariabackup.huge_lsn 'SERVER,strict_full_crc32' w39 [ fail ] timeout after 60 seconds
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With some added logging, I figured out the problem. The fix is quite simple: When we wait for a log checkpoint, we must wait for it to be not behind the latest sampled LSN. On one code path, which matches the test case, we are subtracting from the wait_lsn before waiting, causing buf_flush_wait(wait_lsn, false) to be a no-op (no checkpoint executed, even though there are some dirty pages):
diff --git a/storage/innobase/log/log0log.cc b/storage/innobase/log/log0log.cc
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index ee8d43a68e5..c8aa06b02dc 100644
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--- a/storage/innobase/log/log0log.cc
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+++ b/storage/innobase/log/log0log.cc
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@@ -811,14 +811,15 @@ void log_t::set_archive(my_bool archive, THD *thd) noexcept
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if (archive)
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{
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- wait_lsn-= (wait_lsn - first_lsn) % capacity();
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+ const lsn_t limit{wait_lsn - (wait_lsn - first_lsn) % capacity()};
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/* We are in innodb_log_archive=OFF. If the file has wrapped
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around between the checkpoint and the current position, we must
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wait for a log checkpoint not before the desired first_lsn of
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our innodb_log_archive=ON log file, because that format does not
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allow any wrap-around. */
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- if (checkpoint < wait_lsn)
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+ if (checkpoint < limit)
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goto retry_after_checkpoint;
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+ wait_lsn= limit;
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}
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else if (circular_recovery_from_sequence_bit_0)
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{ |
Attachments
Issue Links
- blocks
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MDEV-14992 BACKUP SERVER to mounted file system
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- In Progress
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- In Testing
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- is caused by
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- Closed
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