sql: Temporarily revert per-statement context forking to address memory leak#17200
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itsbilal merged 1 commit intocockroachdb:masterfrom Jul 24, 2017
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petermattis
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LGTM
This doesn't cause any tests to fail? Seems like there is a hole in the testing of cancellation.
| // Fork context for this statement. | ||
| queryMeta.ctx, queryMeta.cancel = context.WithCancel(session.Ctx()) | ||
| // TODO(itsbilal): Fork a statement-specific context here, that gets cancelled | ||
| // upon request by user. |
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As mentioned privately, perhaps we should create a new context whenever a transaction starts.
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@petermattis Cancellation still works because |
itsbilal
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This reverts some of the changes made in PRs cockroachdb#17003 and cockroachdb#17200. In particular: 17003 made new contexts for every statement, but didn't cancel them after statement execution, resulting in a memory leak. 17200 did a quick-fix for that memory leak by not forking that context, at the expense of not being able to leverage the context in cancellation. This PR restores the context cancellation behaviour introduced in cockroachdb#17003 , except at the transaction level - cancelling a query closes its transaction's context.
itsbilal
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This reverts some of the changes made in PRs cockroachdb#17003 and cockroachdb#17200. In particular: 17003 made new contexts for every statement, but didn't cancel them after statement execution, resulting in a memory leak. 17200 did a quick-fix for that memory leak by not forking that context, at the expense of not being able to leverage the context in cancellation. This PR restores the context cancellation behaviour introduced in cockroachdb#17003 , except at the transaction level - cancelling a query closes its transaction's context.
itsbilal
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This reverts some of the changes made in PRs cockroachdb#17003 and cockroachdb#17200. In particular: 17003 made new contexts for every statement, but didn't cancel them after statement execution, resulting in a memory leak. 17200 did a quick-fix for that memory leak by not forking that context, at the expense of not being able to leverage the context in cancellation. This PR restores the context cancellation behaviour introduced in cockroachdb#17003 , except at the transaction level - cancelling a query closes its transaction's context.
itsbilal
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This reverts some of the changes made in PRs cockroachdb#17003 and cockroachdb#17200. In particular: 17003 made new contexts for every statement, but didn't cancel them after statement execution, resulting in a memory leak. 17200 did a quick-fix for that memory leak by not forking that context, at the expense of not being able to leverage the context in cancellation. This PR restores the context cancellation behaviour introduced in cockroachdb#17003 , except at the transaction level - cancelling a query closes its transaction's context.
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Original PR: #17003
Not cancelling the context right after forking it was causing a memory leak. Simply cancelling the context after every statement doesn't work, since the heartbeat loop detects it and prematurely aborts the transaction (see the comment here).
While I work on a fix, here's a direct revert of just that part of the PR.