FormatOnSave takes a long time

[mdegans]

Preflight Checklist

• I have read the troubleshooting guide
• I have searched existing issues and this is not a duplicate
• This is a bug with the VS Code extension, not with how Prettier formats code

Issue Summary

Issue

Format on save can take minutes to save in vscode. This issue keeps getting closed without being fixed. Unable to repro != issue does not exist.

This seems to not be an issue when first restarting VsCode but after a while save stalls, so possible resource leak maybe? May also be macOS specific. I have not had this happen on other platforms.

Fixes

Uninstall prettier vscode extension.

See Also

• FormatOnSave takes a long time #1333
• Running slow on save Participants #1253

Reproduction Repository

https://github.com/mdegans/misanthropic

Steps to Reproduce

1. Install VsCode extension (on macOS, in my case)
2. Use VsCode for a few hours
3. Try to save. Doesn't seem to matter what format. In my case prettier usually gets in the way of rustfmt.

Expected Behavior

The file gets formatted more or less immediately

Actual Behavior

Save hangs, blocking many things

Operating System

macOS

IDE

VSCode

IDE Version

does not matter

Prettier Extension Version

for a year at least

Prettier Version

3.8.1

Prettier Extension Logs

Uninstalled problematic extension. Logs gone.

Prettier Configuration

[andomorphia]

This seems to not be an issue when first restarting VsCode but after a while save stalls, so possible resource leak maybe? May also be macOS specific. I have not had this happen on other platforms.

Experiencing the same issue since a few days on Windows 11

[RudraMudra]

I am currently encountering the same issue, where the code formatter Prettier takes an excessive amount of time to format and save the lines of code. The cause of this problem is unclear at the moment, and its prolonged execution is impacting the overall efficiency of the workflow.

[lazlojuly]

I am experiencing this also.

[ideal-railroad]

I had the same issue, with VS Code blaming Prettier for taking too long, pastes taking a long time (I've never seen a spinner for pastes before), and sometimes VS Code seemingly giving up on saving the file.

In my case I traced it to TypeScript itself, or, actually, how I was torturing TypeScript. I had just started using the schema-dts type library, and specifically, I was using the Thing type, which is a massive recursive discriminated union. I saw the TypeScript extension crash several times by the time I finally diagnosed it. VS Code was blaming Prettier for something that had nothing to do with Prettier.

If you find yourself in a similar spot, you can use the "TypeScript: Open TS Server log" command from a TypeScript file, which will probably require you to restart TypeScript. Several entries will have timings attached. Mine included an entry 36::encodedSemanticClassifications-full: elapsed time (in milliseconds) 21173.3887, which seemed to be a pretty good indicator of trouble.

Look for a line that begins:

{"seq":0,"type":"event","event":"requestCompleted","body":{"request_seq":3,"performanceData":{"diagnosticsDuration":[{...

That contains timing data for all open TypeScript files. Copy and paste it into another window and format it to see it better. Look for files with timing issues and focus on them (times are in milliseconds):

{
  "syntaxDiag": 0.02479999999923166,
  "semanticDiag": 26342.76800000000003,
  "suggestionDiag": 0.2842999999993481,
  "file": "/workspaces/ferrous/equine/src/components/metadata.tsx"
},

When I stopped using the Thing discriminated union and created a more limited union for TypeScript to parse, everything went back to normal, and VS Code stopped blaming Prettier.