Only prefetch on successful partial read #4658
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SandyXSD
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Apr 8, 2024
pkg/chunk/cached_store.go
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| return n, nil | ||
| } else { | ||
| s.store.objectReqErrors.Add(1) | ||
| return n, err |
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we want to try everything we can do before failure, don't return here.
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We need a way to distinguish retriable errors, otherwise we will have a large read amplification.
pkg/vfs/reader.go
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| @@ -224,7 +224,7 @@ func (s *sliceReader) run() { | |||
| _ = f.r.m.InvalidateChunkCache(meta.Background, inode, indx) | |||
| if f.tried > f.r.maxRetries { | |||
| s.done(err, 0) | |||
| } else { | |||
| } else { // Why retry here since we already have retried in `cachedStore.load`? | |||
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This is another level of retry. The slices obtained from the meta.Read method may be changed.
Signed-off-by: Changxin Miao <[email protected]>
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When s3 storage is unhealthy, we see lots of failed read requests for the same key - half of them are triggered by prefetch. Actually only a successful partial read needs a prefetch.