[narwhal] fix unlocking resources in header_waiter when error #5954
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akichidis
commented
Nov 9, 2022
| self.cleanup_pending_requests(&header); | ||
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| // Ok to drop the header if core is overloaded. | ||
| let _ = self.tx_headers_loopback.try_send(header); |
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When we used to have retries in header_waiter it was ok to not send the header back to core - and do it only in the success scenario (like here). I believe though this now could create under some circumstances a loss of liveness. I keep the behaviour as is and not re-send header back to Core in case of error so can avoid any infinite loop that could be caused here without necessary backoff. As I said on the description @aschran will completely remove this component so don't want to spend more effort now
aschran
approved these changes
Nov 9, 2022
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This PR is fixing an undesired behaviour in
header_waiter. When a request fails (ex fetch batches or fetch parents) we simplywarnbut we do not clear the internal maps. So any next attempt to fetch those will simply get ignored. We saw a few cases in restartability where this behaviour ended up in loss of liveness.Now, this component is not only having this issue and there are several things that should be fixed (ex the way we perform the clean ups, no retries which again can lead to loss of liveness). I am not performing any further refactoring as I know that @aschran is working to remove completely, but I prefer to have something now so could fix at least a known problem.