Don't use Lock for heavily accessed CrateMetadata::cnum_map. #50532
Conversation
This file contains hidden or 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
rust-highfive
added
the
S-waiting-on-review
|
@bors: r+ |
|
📌 Commit ea49428 has been approved by |
bors
added
S-waiting-on-bors
|
@bors rollup |
alexcrichton
added a commit
to alexcrichton/rust
that referenced
this pull request
May 10, 2018
… r=Zoxc Don't use Lock for heavily accessed CrateMetadata::cnum_map. The `cnum_map` in `CrateMetadata` is used for two things: 1. to map `CrateNums` between crates (used a lot during decoding) 2. to construct the (reverse) post order of the crate graph For the second case, we need to modify the map after the fact, which is why the map is wrapped in a `Lock`. This is bad for the first case, which does not need the modification and does lots of small reads from the map. This PR splits case (2) out into a separate `dependencies` field. This allows to make the `cnum_map` immutable (and shifts the interior mutability to a less busy data structure). Fixes rust-lang#50502 r? @Zoxc
alexcrichton
added a commit
to alexcrichton/rust
that referenced
this pull request
May 10, 2018
… r=Zoxc Don't use Lock for heavily accessed CrateMetadata::cnum_map. The `cnum_map` in `CrateMetadata` is used for two things: 1. to map `CrateNums` between crates (used a lot during decoding) 2. to construct the (reverse) post order of the crate graph For the second case, we need to modify the map after the fact, which is why the map is wrapped in a `Lock`. This is bad for the first case, which does not need the modification and does lots of small reads from the map. This PR splits case (2) out into a separate `dependencies` field. This allows to make the `cnum_map` immutable (and shifts the interior mutability to a less busy data structure). Fixes rust-lang#50502 r? @Zoxc
bors
added a commit
that referenced
this pull request
May 10, 2018
Rollup of 18 pull requests Successful merges: - #49423 (Extend tests for RFC1598 (GAT)) - #50010 (Give SliceIndex impls a test suite of girth befitting the implementation (and fix a UTF8 boundary check)) - #50447 (Fix update-references for tests within subdirectories.) - #50514 (Pull in a wasm fix from LLVM upstream) - #50524 (Make DepGraph::previous_work_products immutable) - #50532 (Don't use Lock for heavily accessed CrateMetadata::cnum_map.) - #50538 ( Make CrateNum allocation more thread-safe. ) - #50564 (Inline `Span` methods.) - #50565 (Use SmallVec for DepNodeIndex within dep_graph.) - #50569 (Allow for specifying a linker plugin for cross-language LTO) - #50572 (Clarify in the docs that `mul_add` is not always faster.) - #50574 (add fn `into_inner(self) -> (Idx, Idx)` to RangeInclusive (#49022)) - #50575 (std: Avoid `ptr::copy` if unnecessary in `vec::Drain`) - #50588 (Move "See also" disambiguation links for primitive types to top) - #50590 (Fix tuple struct field spans) - #50591 (Restore RawVec::reserve* documentation) - #50598 (Remove unnecessary mutable borrow and resizing in DepGraph::serialize) - #50606 (Retry when downloading the Docker cache.) Failed merges: - #50161 (added missing implementation hint) - #50558 (Remove all reference to DepGraph::work_products)
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
4 participants
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.
The
cnum_mapinCrateMetadatais used for two things:CrateNumsbetween crates (used a lot during decoding)For the second case, we need to modify the map after the fact, which is why the map is wrapped in a
Lock. This is bad for the first case, which does not need the modification and does lots of small reads from the map.This PR splits case (2) out into a separate
dependenciesfield. This allows to make thecnum_mapimmutable (and shifts the interior mutability to a less busy data structure).Fixes #50502
r? @Zoxc