Use :npm-deps false to speed up Figwheel startup

[dmitryn]

Description

Latest version of ClojureScript supports :npm-deps false compiler option.
It might speed up Figwheel start by 20-45 seconds bhauman/lein-figwheel#678
https://twitter.com/mfikes/status/986040242997284865?s=09

Solution

Add npm-deps false compiler option to dev builds. Compile builds for ios and android. Check if it increases Figwheel perfomance.

Twitter

Mike Fikes on Twitter

“If you have a ClojureScript project where there also just happens to be a node_modules directory sitting there that ClojureScript itself doesn’t actually use (for example for React Native), :npm-deps false will be your new best friend. (It saves me 20 to 45 seconds of startup.)”

[status-open-bounty]

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[debragail]

Can you post the current performance metrics and logs?

[debragail]

bhauman/lein-figwheel#678

[dmitryn]

I don't have one. It's actually in scope of this issue to collect and compare such metrics.

[debragail]

It looks like you use he node_modules folder according to this file:

findSymlinkedModules.js.patch

/**

• Copyright (c) 2015-present, Facebook, Inc.
• All rights reserved.
• This source code is licensed under the BSD-style license found in the
• LICENSE file in the root directory of this source tree. An additional grant
• of patent rights can be found in the PATENTS file in the same directory.
• @Format
• @flow
  */

const path = require('path');
const fs = require('fs');

/**

• Find symlinked modules inside "node_modules."
• Naively, we could just perform a depth-first search of all folders in
• node_modules, recursing when we find a symlink.
• We can be smarter than this due to our knowledge of how npm/Yarn lays out
• "node_modules" / how tools that build on top of npm/Yarn (such as Lerna)
• install dependencies.
• Starting from a given root node_modules folder, this algorithm will look at
• both the top level descendants of the node_modules folder or second level
• descendants of folders that start with "@" (which indicates a scoped
• package). If any of those folders is a symlink, it will recurse into the
• link, and perform the same search in the linked folder.
• The end result should be a list of all resolved module symlinks for a given
• root.
  */
  module.exports = function findSymlinkedModules(
  projectRoot: string,
  ignoredRoots: Array = [],
  ) {
  const timeStart = Date.now();
  const nodeModuleRoot = path.join(projectRoot, 'node_modules');
  const resolvedSymlinks = findModuleSymlinks(nodeModuleRoot, [
  ...ignoredRoots,
  projectRoot,
  ]);
  const timeEnd = Date.now();

console.log(
Scanning folders for symlinks in ${nodeModuleRoot} (${timeEnd - timeStart}ms),
);

return resolvedSymlinks;
};

function findModuleSymlinks(
modulesPath: string,
ignoredPaths: Array = [],
): Array {
if (!fs.existsSync(modulesPath)) {
return [];
}

// Find module symlinks
const moduleFolders = fs.readdirSync(modulesPath);
const symlinks = moduleFolders.reduce((links, folderName) => {
const folderPath = path.join(modulesPath, folderName);
const maybeSymlinkPaths = [];
if (folderName.startsWith('@')) {
const scopedModuleFolders = fs.readdirSync(folderPath);
maybeSymlinkPaths.push(
...scopedModuleFolders.map(name => path.join(folderPath, name)),
);
} else {
maybeSymlinkPaths.push(folderPath);
}
return links.concat(resolveSymlinkPaths(maybeSymlinkPaths, ignoredPaths));
}, []);

// For any symlinks found, look in that modules node_modules directory
// and find any symlinked modules
const nestedSymlinks = symlinks.reduce(
(links, symlinkPath) =>
links.concat(
// We ignore any found symlinks or anything from the ignored list,
// to prevent infinite recursion
findModuleSymlinks(path.join(symlinkPath, 'node_modules'), [
...ignoredPaths,
...symlinks,
]),
),
[],
);

return [...new Set([...symlinks, ...nestedSymlinks])];
}

function resolveSymlinkPaths(maybeSymlinkPaths, ignoredPaths) {
return maybeSymlinkPaths.reduce((links, maybeSymlinkPath) => {
if (fs.lstatSync(maybeSymlinkPath).isSymbolicLink()) {
const resolved = path.resolve(
path.dirname(maybeSymlinkPath),
fs.readlinkSync(maybeSymlinkPath),
);
if (ignoredPaths.indexOf(resolved) === -1 && fs.existsSync(resolved)) {
links.push(resolved);
}
}
return links;
}, []);
}

[debragail]

Also I don’t know react native tooling that well but it seems to be an issue with 16:

facebook/react-native#15371