Bayes: sort tokens in MySQL store to prevent InnoDB deadlocks - #40
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bayes_token is InnoDB with PRIMARY KEY (id, token), so every token write takes a row lock on the clustered index. _put_tokens and tok_touch_all iterated tokens in Perl hash / caller order, which is randomized per process, so two concurrent scans that share tokens could lock the same rows in opposite orders and deadlock. Sorting the tokens gives every writer a single global lock order, so the circular wait cannot form. The token column is binary(5), so Perl's default string sort matches InnoDB's byte ordering on the clustered index. Also, replace `dbg` with `warn` so future MySQL errors are visible in the logs.
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I believe this fixes bug 7363 |
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bayes_token is InnoDB with PRIMARY KEY (id, token), so every token write takes a row lock on the clustered index. _put_tokens and tok_touch_all iterated tokens in Perl hash / caller order, which is randomized per process, so two concurrent scans that share tokens could lock the same rows in opposite orders and deadlock resulting in the following
error:
Sorting the tokens gives every writer a single global lock order, so the circular wait cannot form. The token column is binary(5), so Perl's default string sort matches InnoDB's byte ordering on the clustered index.
Also, replace
dbgwithwarnso future MySQL errors are visible in the logs.