backupccl: fix key rewriter race in generative split and scatter processor#96313
backupccl: fix key rewriter race in generative split and scatter processor#96313craig[bot] merged 1 commit intocockroachdb:masterfrom
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| return nil, err | ||
| } | ||
| numSplitWorkers := int(spec.NumNodes) | ||
| numSecondSplitWorkers := 2 * numSplitWorkers |
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can we add a comment here about why we chose 2 * numSplitWorkers? I realize this is probably not your doing but a high level reason explaining the factor of 2 would be useful.
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done, I can't really find out why exactly the factor of 2 was chosen but I edited the TODO to perhaps tune it in the future.
| @@ -342,8 +360,8 @@ func runGenerativeSplitAndScatter( | |||
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| // TODO(pbardea): This tries to cover for a bad scatter by having 2 * the | |||
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can we move this TODO with the 2* and think about whether it is still applicable? If we want to punt the thinking for later can we add your or my name in the TODO 😋
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I moved the TODO to where the factor of 2 is and put my name on it.
| // scatterers contain the splitAndScatterers for the first group of split and | ||
| // scatter workers. Each worker needs its own scatterer as one cannot be used | ||
| // concurrently. | ||
| scatterers []splitAndScatterer |
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What do you think about calling this one chunkSplitAndScatterer and in the comment indicating that these are used to split and scatter importSpanChunks?
Then the one below can be called chunkEntrySplitAndScatterer or entrySplitAndScatterer? It doesn't perform scatters so maybe we mention that in the comment and describe what it does.
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done, renamed and added the comments.
| flowCtx: flowCtx, | ||
| spec: spec, | ||
| output: output, | ||
| scatterers: scatterers[:numSplitWorkers], |
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sanity checking that this creates a copy of the scatterers slice and doesn't just copy the pointer
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these do just copy the pointer but I changed the code to use two slices just so that we are not confused in the future.
| g := ctxgroup.WithContext(ctx) | ||
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| splitWorkers := int(spec.NumNodes) | ||
| splitWorkers := len(scatterers) |
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nit: maybe we call this splitAndScatterWorkers since they do both?
| @@ -291,6 +308,7 @@ func runGenerativeSplitAndScatter( | |||
| importSpanChunksCh := make(chan scatteredChunk, splitWorkers*2) | |||
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I should've done this in your previous PR sorry, but do you think you could add a line or two above each goroutine in this method describing what each of them does?
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done, added comments.
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you need a rebase to get past the failing DD tests, I ran into the same thing this morning. Since you're going to push anyways can I also bug you to change the |
…essor The generative split and scatter processor is currently causing tests to fail under race because there are many goroutines that are operating with the same splitAndScatterer, which cannot be used concurrently as the underlying key rewriter cannot be used concurrently. Modify the processor so that every worker that uses the splitAndScatterer now uses its own instance. Fixes: cockroachdb#95808 Release note: None
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bors r+ |
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Build succeeded: |
The generative split and scatter processor is currently causing tests to fail under race because there are many goroutines that are operating with the same splitAndScatterer, which cannot be used concurrently as the underlying key rewriter cannot be used concurrently. Modify the processor so that every worker that uses the splitAndScatterer now uses its own instance.
Fixes: #95808
Release note: None