The exception thrown by Node.js's fs.statSync function contains a stack
trace that can be expensive to compute. Since this exception isn't used
by fileSystemEntryExists, we can safely set Error.stackTraceLimit to 0
without a change in behavior.
---
A significant performance improvement was noticed with this change while
profiling tsserver on packages within a proprietary monorepo.
Specifically, my team saw high self time percentages for Node.js's
uvException and handleErrorFromBinding internal functions. These
functions are executed within fs.statSync when it fails to find the
given path.
https://user-images.githubusercontent.com/906558/90183227-220cb800-dd81-11ea-8d61-f41f89481f46.png
fs.statSync: https://github.com/nodejs/node/blob/v14.4.0/lib/fs.js#L1030-L1037
handleErrorFromBinding: https://github.com/nodejs/node/blob/v14.4.0/lib/internal/fs/utils.js#L254-L269
uvException: https://github.com/nodejs/node/blob/v14.4.0/lib/internal/errors.js#L390-L443
## Measurements
After adding Error.stackTraceLimit = 0, we saw:
- For a large configured project with 12,565 files, tsserver reached the
projectLoadingFinish event 48.78% faster. (~46.786s vs ~31.447s)
- For a medium project with 7,064 files, tsserver was 25.75% faster.
(~20.897s vs ~16.618s)
- For a small project with 796 files, tsserver was only a negligible
3.00% faster. (~3.545s vs ~3.442)
Measurements were taken on macOS 10.15.6, Node.js 14.4.0, and a recent
master commit of TypeScript (610fa28d). The average of 3 runs before and
after this change were taken.
I would normally include .cpuprofile and isolate-*-*-*.log files, but
can't post them publicly in this case. If there's any other summaries
the TypeScript team would be curious about I can report them.
## fs.statSync Misses
Within our monorepo, the fs.statSync misses were mostly searches for
alternative file extensions of module imports.
- For node_modules imports, a lot of .ts/.tsx lookups failed until the
.d.ts file was found.
- Within projects with a lot of JSX files, .ts files were looked for
before finding the .tsx version.
- In the medium scale project mentioned above, a total of 38,515
non-existent files were queried during createProgram.
* Bind alias ThisProperty assignment declarations
This is a quick prototype that does the wrong thing at the wrong time
with the wrong technique.
* Preliminary checker handling for aliases
Duplicative and untested, but I think I updated all the places that need
updating.
* new is error; old one should not have been removed
* I don't even know what's happening with this test
* cleanup and testing in the checker
* binder: use lookupSymbolForNameWorker instead of mutable
This should have about the same behaviour and is much easier to
understand.
Also refactor common code a bit.
* Shorter name of lookupSymbolForName
Once upon a time there was a parent/worker function, but now it's just a
single function again. No need for the -Worker suffix.
* remove oodate comment
* fix switch-case-break lint
* Refactor and move functions
* Rename and improve type of getContextualTypeForAssignmentDeclaration
* Preserve the variable name when exporting an arrow or anonymous function
This allows the browser or node to properly name the (arrow) function
* Updated tests to reflect previous change
* Remove duplicated comment
* Transforms variable.initializer using moduleExpressionElementVisitor
* PR feedback: rbuckton
- Use isArrowFunction and isFunctionExpression
* PR feedback: rbuckton
- Consider ClassExpresion, they can also be named based on the
variable.
* Use isUncalledFunctionReference for aliases too
Fixes bogus deprecated notices on imports of functions with deprecated
overloads, but with some non-deprecated overloads.
Fixesmicrosoft/vscode#104238
* Just check all declarations, don't call isUncalledFunction
PR #38449 changed the second overload of the constructor for Int8,
Uint8, Int32, Uint32, Int16, Uint16, Float, Float64 -Array so that it no
longer includes `ArrayBufferLike`. It's just `ArrayLike<number>`.
This is fine except in the case that
the caller provides exactly `ArrayLike<number> | ArrayBufferLike`. This
PR adds ArrayBufferLike back so that the union is once again accepted.
This avoids a breaking change, in particular in one Microsoft-internal
codebase.
* Add separate flag serverMode for server mode to allow back compatibility
* Addressed code review feedback.
Co-authored-by: Daniel Rosenwasser <DanielRosenwasser@users.noreply.github.com>
* Limit auto import provider project size
* Add test
* Make option configurable
* Fix test
* Only bail when setting is auto
* Fix other test
* Update API baseline
