perf: make sure we use multiple threads when scanning #1705
Conversation
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
wjones127
commented
Dec 13, 2023
Comment on lines
+399
to
+402
| // If contiguous, continue | ||
| if indices[i + 1] == indices[i] { | ||
| continue; | ||
| } |
There was a problem hiding this comment.
This fixes a performance bug for large vectors. If we have vectors larger than the block size (1536-dim f32 vectors are 6,144 bytes while the default block size on local fs is 4K), then without this line we make a range request for every vector we take. 😱
westonpace
approved these changes
Dec 13, 2023
| @@ -294,7 +294,12 @@ impl FragmentScanner { | |||
| let stream = futures::stream::iter(simplified_predicates.into_iter().enumerate()).map( | |||
| move |(batch_id, predicate)| { | |||
| let scanner_ref = scanner.clone(); | |||
| async move { scanner_ref.read_batch(batch_id, predicate).await } | |||
| tokio::task::spawn(async move { scanner_ref.read_batch(batch_id, predicate).await }) | |||
There was a problem hiding this comment.
Would buffered / buffer_unordered not work here?
There was a problem hiding this comment.
We do call it below, it's just not sufficient. Each of the read_batch() tasks has some CPU-bound work, which can block IO of other tasks if they are in the same thread. By spawning, we distribute the tasks amongst threads, ensuring we get concurrency.
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
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Outdated suggestions cannot be applied.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.
No description provided.