[Execution] Fix stop control #5327
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Additional details and impacted files@@ Coverage Diff @@
## master #5327 +/- ##
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Coverage 55.70% 55.70%
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Files 1004 1003 -1
Lines 97080 97017 -63
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- Hits 54082 54048 -34
+ Misses 38929 38899 -30
- Partials 4069 4070 +1
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zhangchiqing
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zhangchiqing
requested review from
janezpodhostnik,
peterargue and
sideninja
and removed request for
ramtinms
| @@ -205,7 +205,8 @@ func (e *Engine) BlockProcessable(b *flow.Header, _ *flow.QuorumCertificate) { | |||
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| // TODO: this should not be blocking: https://github.com/onflow/flow-go/issues/4400 | |||
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| // skip if stopControl tells to skip | |||
| // skip if stopControl tells to skip, so that we can avoid fetching collections | |||
| // for this block | |||
| if !e.stopControl.ShouldExecuteBlock(b) { | |||
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Right now, this is the only place we check.
| @@ -363,6 +364,12 @@ func (e *Engine) executeBlock( | |||
| ctx context.Context, | |||
| executableBlock *entity.ExecutableBlock, | |||
| ) { | |||
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| // don't execute the block if the stop control says no | |||
| if !e.stopControl.ShouldExecuteBlock(executableBlock.Block.Header) { | |||
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Stop control should check again here, because otherwise there is an edge case that might execute blocks above the stop height. See the comment on L457
The edge case is that, when a block becomes processable, the stop height might not be set, so it's added to the queue, however, when it becomes executable and is able to execute, the stop height is set, and should not be executed. Without this check, it will be executed, but should not.
| @@ -454,8 +463,6 @@ func (e *Engine) executeBlock( | |||
| e.executionDataPruner.NotifyFulfilledHeight(executableBlock.Height()) | |||
| } | |||
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| e.stopControl.OnBlockExecuted(executableBlock.Block.Header) | |||
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stopControl.OnBlockExecuted is to report a block has been executed and triggers stop control to check whether it should stop/crash or not.
However, this is currently called after e.onBlockExecuted is called, which checks if the child block (next block) can be executed and executes if completed. So imaging the following case:
Given two blocks: A <- B and we set stop height as B, meaning stop as soon as A is executed, and don't execute B. OK, now both block A and B's collections have been received, after A is executed, B becomes ready to be executed, if onBlockExecued(A) is called before stopControl.OnBlockExecuted, then it will execute block B in another go routine (which shouldn't). But the reason we never ran into this, is probably because before B is executed, stop.OnBlockExecuted might have been called and crashed the node. However, B technically still have a chance to be executed, I didn't notice this until looking into a flakey test TestStopAtHeightWhenExecutedBeforeFinalized which captured this edge case.
So my solution here is to 1) move this line up before the onBlockExecuted, so that we let stop control check stop condition first. And 2) add ShouldExecuteBlock into the executeBlock function, so that even if stop control decides not to crash, and the function onBlockExecuted found the next block has received its collection and can be executed, and we can still stop the next block from being executed.
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@peterargue sorry, I just realized my comments in the PR was in "pending". I just published them. |
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This PR fixes the stop control when ingestion engine is about to execute next block. See details in the comments of the PR.