perf(bazel): use allowedInputs to avoid fs.stat #46069
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Call tsc_wrapped's fileExists function instead of TypeScript's. tsc_wrapped (used internally by ngc-wrapped) has an optimization under bazel to avoid file system calls where possible. It takes advantage bazelOpts.allowedInputs, which contains a list of all files available for compilation. File system calls can be quite slow depending on the file system. In google3 I saw a 38 seconds compilation, which spent 6 seconds just doing fs.stat calls during module resolution. Those fs.stat calls are entirely gone after with this change.
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Here are screenshots of a CPU profile before and after the change:
More details are in an internal ticket: http://b/232199273#comment2 |
devversion
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May 20, 2022
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action: merge
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Presubmit: cl/449952536 (we want to wait for a TGP) |
devversion
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action: merge
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This PR was merged into the repository by commit 7efa09b. |
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Call tsc_wrapped's fileExists function instead of TypeScript's. tsc_wrapped (used internally by ngc-wrapped) has an optimization under bazel to avoid file system calls where possible. It takes advantage bazelOpts.allowedInputs, which contains a list of all files available for compilation. File system calls can be quite slow depending on the file system. In google3 I saw a 38 seconds compilation, which spent 6 seconds just doing fs.stat calls during module resolution. Those fs.stat calls are entirely gone after with this change. PR Close #46069
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PR Checklist
Regarding tests: Do you have a way to test for file system calls during compilation?
PR Type
What is the current behavior?
ngc-wrapped calls TypeScript's fileExists function during module resolution, which calls fs.statSync.
File system calls can be quite slow depending on the file system. In google3 I saw a 38 seconds compilation, which spent 6 seconds just doing fs.stat calls during module resolution.
What is the new behavior?
Call tsc_wrapped's fileExists function instead of TypeScript's.
tsc_wrapped (used internally by ngc-wrapped) has an optimization under bazel to avoid file system calls where possible. It takes advantage bazelOpts.allowedInputs, which contains a list of all files available for compilation.
The fs.stat calls mentioned for the slow google3 target are entirely gone after with this change.
Does this PR introduce a breaking change?