feat: try reading shard_cache if prefetcher blocking_get returns None #8287
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| self.metrics.prefetch_retry.inc(); | ||
| self.read_from_db(hash)? | ||
| if let Some(value) = self.shard_cache.get(hash) { | ||
| value |
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@jakmeier do you think it is worth introducing another metric for this case, something like:
self.metrics.prefetch_shared_cache_after_pending.inc();
also suggestions for a better name are welcome :)
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Hm, yeah I think we can add it. It's exactly these weird corner cases that are hard to debug, having insight with metrics might turn out useful.
For the name, do you mean shard_cache or shared_cache? I think prefetch_shard_cache_after_pending makes more sense to me.
But actually, how about prefetch_pending_conflict, or prefetch_pending_conflict_hit, or prefetch_main_thread_conflict or even just prefetch_conflict?
My thinking is: The request was pending but instead of the expected prefetch-hit afterwards, there was a conflict with "another main thread" that also lead to a hit, but the hit was unexpectedly in shard cache. You name also work though, these are just some suggestions.
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it meant to be shard_cache, sorry for the typo
prefetch_conflict definitely makes to me, let's use it
This is the second part of #7723: avoid an unnecessary storage lookup from the main thread in the scenario of forks.