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Set stackTraceLimit to 0 in fileSystemEntryExists #40043

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Merged
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Aug 18, 2020
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Set stackTraceLimit to 0 in fileSystemEntryExists #40043

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8 changes: 8 additions & 0 deletions src/compiler/sys.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -1662,6 +1662,11 @@ namespace ts {
}

function fileSystemEntryExists(path: string, entryKind: FileSystemEntryKind): boolean {
// Since the error thrown by fs.statSync isn't used, we can avoid collecting a stack trace to improve
// the CPU time performance.
const originalStackTraceLimit = Error.stackTraceLimit;
Error.stackTraceLimit = 0;

try {
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Another option is to just return using existsSync and ignore directory or file and make our code more tolerant (it might already be) for finding file instead of directory or vice versa. That could give us better perf in both cases.

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Definitely. I was also wondering how necessary it was to check for file versus folder existence.

I'm guessing the current behavior of this function is this way so folders ending with .ts get ignored. Is that an edge case where a behavior change would be acceptable?

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If you make a change we can see what user tests break and see what happens

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Ended up not doing this and favoring Error.stackTraceLimit = 0 instead. I assume we wanted to try using existsSync entirely since we were worried about perf in the path exists case. Setting Error.stackTraceLimit = 0 should improve performance when files don't exist with no change to checking files that do exist.

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Nice!

const stat = _fs.statSync(path);
switch (entryKind) {
Expand All @@ -1673,6 +1678,9 @@ namespace ts {
catch (e) {
return false;
}
finally {
Error.stackTraceLimit = originalStackTraceLimit;
}
}

function fileExists(path: string): boolean {
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