MDEV-37977 InnoDB deadlock report incorrectly reports rolled back transaction number#4679
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arcivanov wants to merge 1 commit intoMariaDB:10.11from
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MDEV-37977 InnoDB deadlock report incorrectly reports rolled back transaction number#4679arcivanov wants to merge 1 commit intoMariaDB:10.11from
arcivanov wants to merge 1 commit intoMariaDB:10.11from
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…nsaction number The "WE ROLL BACK TRANSACTION (N)" message in the deadlock report referred to the wrong transaction number. The victim selection loop and the display loop in `Deadlock::report()` traversed the cycle in the same order (`cycle->wait_trx, ..., cycle`) but used misaligned position numbering: - **Victim selection** initialized `victim = cycle` at position 1 *before* the loop, then started iterating from `cycle->wait_trx` at position 2. - **Display loop** started from `cycle->wait_trx` at label `(1)`, with `cycle` displayed last at label `(N)`. This caused `victim_pos` to be off by one relative to the displayed transaction labels. Fix: restructure the victim selection loop to start with `l=0` and `victim=nullptr`, letting the loop handle all transactions uniformly. The first iteration unconditionally picks `cycle->wait_trx` as the initial victim at position 1, matching the display loop. The `thd_deadlock_victim_preference()` call is guarded with a `victim != nullptr` check to skip it on the first iteration (where no prior victim exists to compare against).
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The "WE ROLL BACK TRANSACTION (N)" message in the deadlock report referred to the wrong transaction number. The victim selection loop and the display loop in
Deadlock::report()traversed the cycle in the same order (cycle->wait_trx, ..., cycle) but used misaligned position numbering:victim = cycleat position 1 before the loop, then started iterating fromcycle->wait_trxat position 2.cycle->wait_trxat label(1), withcycledisplayed last at label(N).This caused
victim_posto be off by one relative to the displayed transaction labels.Fix: restructure the victim selection loop to start with
l=0andvictim=nullptr, letting the loop handle all transactions uniformly. The first iteration unconditionally pickscycle->wait_trxas the initial victim at position 1, matching the display loop. Thethd_deadlock_victim_preference()call is guarded with avictim != nullptrcheck to skip it on the first iteration (where no prior victim exists to compare against).