eth/fetcher: don't skip block/header when parent is not found #633
Add this suggestion to a batch that can be applied as a single commit.
This suggestion is invalid because no changes were made to the code.
Suggestions cannot be applied while the pull request is closed.
Suggestions cannot be applied while viewing a subset of changes.
Only one suggestion per line can be applied in a batch.
Add this suggestion to a batch that can be applied as a single commit.
Applying suggestions on deleted lines is not supported.
You must change the existing code in this line in order to create a valid suggestion.
Outdated suggestions cannot be applied.
This suggestion has been applied or marked resolved.
Suggestions cannot be applied from pending reviews.
Suggestions cannot be applied on multi-line comments.
Suggestions cannot be applied while the pull request is queued to merge.
Suggestion cannot be applied right now. Please check back later.
Currently, we simply skip importing block/header when parent block/header is not found. However, since multiple blocks can be imported in parallel, the not found parent might be due to the fact that the parent import does not finish yet. This leads to a suitation that the correct block in canonical chain is skipped and the node gets stuck until the peer timeout. We observe this behavior when there are reorgs and block import is time consuming.
This commit fixes it by creating a new queue for those missing parent blocks and re-import them after the parent is imported.