Luke Pighetti lukepighetti

I was trying to do some performance profiling of our production app and I noticed a certain function was taking a lot more time than I expected (350ms vs 1ms), so I started to dig deeper. In doing so, it looked like if I changed that function from a Future<String> to a String with no other code changes (it could have been written as a FutureOr), the execution time of that code branch reduced to expected levels.

I posted about this on Twitter and created a reproduction.

https://twitter.com/luke_pighetti/status/1630255285372633089?s=20

This code runs in a fresh Flutter app on iOS Simulator.

It almost looks like a flurry of concurrent Futures are queueing up and delaying other futures.

	import 'dart:io';

	import 'package:figma_squircle/figma_squircle.dart';
	import 'package:flutter/widgets.dart';

	class RoundedRectangle extends StatelessWidget {
	const RoundedRectangle({
	super.key,
	this.radius = 10,
	this.height,

	import 'package:app/extensions.dart';
	import 'package:flutter/material.dart';

	class AutoFillText extends StatelessWidget {
	const AutoFillText(
	this.text, {
	super.key,
	this.textStyle,
	this.minFontSize = 18,
	});

	import 'package:firebase_analytics/firebase_analytics.dart';
	import 'package:flutter/material.dart';
	import 'package:provider/provider.dart';
	import 'package:shared_preferences/shared_preferences.dart';

	import '/app/store_architecture.dart';
	import '/feedback/feedback_store.dart';
	import '/par/par_store.dart';
	import '/settings/settings_binding_observer.dart';
	import '/settings/settings_store.dart';


	extension on WidgetTester {
	Future<void> launchApp() async {
	await app.main();
	await pumpAndSettle();
	}

	Future<void> clearState() async {
	await SharedPreferences.getInstance().then((it) => it.clear());
	}

	# flask --app server run

	from dataclasses import dataclass, asdict
	from typing import Generic, List, TypeVar
	from flask import Flask

	app = Flask(__name__)

	T = TypeVar("T")

	# launch daily notes with `notes`
	# launch specific notes with `notes woodworking`
	# this is a cloud synced file, so it's live on all my devices
	function notes(){
	SUBJECT="${1:=daily}"
	if [ -z "$SUBJECT" ]
	then
	(cd ~/Documents/notes && hx NOTES.md)
	else
	(cd ~/Documents/notes && hx "${SUBJECT:u}.md" NOTES.md)

	http://bloodgate.com/perl/graph/manual/
	https://twitter.com/luke_pighetti/status/1624102015142965274
	https://github.com/maaslalani/slides

	[keys.normal]
	C-f = [":new", ":insert-output lf-pick", ":theme default", "select_all", "split_selection_on_newline", "goto_file", "goto_last_modified_file", ":buffer-close!", ":theme tokyonight_storm"]

	const centerColumnWidthFactor = 0.4;

	// Prioritizes center with adjustable width factor
	// Fills column left, then right
	// Then splits right column vertically
	// Then splits left column vertically
	function layout() {
	return {
	name: "Ultrawide Simple",
	getFrameAssignments: (windows, screenFrame) => {