Bug in iavlIterator.Close() can cause race condition (store/iavl/store.go)

[wangkui0508]

Summary of Bug

In store/iavl/store.go, the implementation of "func (iter *iavlIterator) Close()" does not wait iterateRoutine to fully exit. So, after Close() returns, iterateRoutine can still run for a while, which may cause race condition.

Version

v0.37.4

Steps to Reproduce

Hard to reproduce, since it is a race condition. In our not-opensourced-yet project, we occasionally meet this bug.

The following code can fix this bug:

func (iter *iavlIterator) Close() {
	close(iter.quitCh)
	// wait iter.iterCh to close
	for range iter.iterCh {}
}

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For Admin Use

• Not duplicate issue
• Appropriate labels applied
• Appropriate contributors tagged
• Contributor assigned/self-assigned

[alexanderbez]

Alternatively, can't we send on a "done" channel in iterateRoutine after we call close(iter.iterCh) and then wait on that done channel in Close()?

[wangkui0508]

Yes, I believe your method can also work.