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fix: release the connection when a transaction fails to start - #839
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felipera87 wants to merge 2 commits into
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beginTransaction called cb(err) without connection.release() when SET TRANSACTION ISOLATION LEVEL or BEGIN failed, so every failed start kept a pooled connection for good. A few of them drain the pool and every later query waits for ever. Signed-off-by: Felipe Reis <felipe@pruvo.com>
Signed-off-by: Felipe Reis <felipe@pruvo.com>
felipera87
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dhmlau and
marioestradarosa
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September 25, 2026 01:42
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When SET TRANSACTION ISOLATION LEVEL or BEGIN fails, beginTransaction calls back with the error but never releases the connection it took from the pool. Each failed start keeps one connection for good, so a few of them drain the pool and every later query waits forever.
We hit this in production. Our database refused a burst of SET SESSION TRANSACTION statements while it was low on memory, every pooled connection leaked, and requests hung until the HTTP timeout.
The fix releases the connection on the three error paths. The new tests use a pool with a single connection and check that a follow-up query still runs after a failed start. They fail on master.