fix: expire env maps, closes #1906

packages/@vue/cli-shared-utils/lib/env.js

@@ -1,11 +1,18 @@
 const { execSync } = require('child_process')
 const fs = require('fs')
 const path = require('path')
+const LRU = require('lru-cache')
 
 let _hasYarn
-const _yarnProjects = new Map()
+const _yarnProjects = new LRU({
+  max: 10,
+  maxAge: 1000
+})
 let _hasGit
-const _gitProjects = new Map()
+const _gitProjects = new LRU({
+  max: 10,
+  maxAge: 1000
+})
 
 // env detection
 exports.hasYarn = () => {

packages/@vue/cli-shared-utils/package.json

@@ -23,6 +23,7 @@
     "execa": "^0.10.0",
     "joi": "^13.0.0",
     "launch-editor": "^2.2.1",
+    "lru-cache": "^4.1.3",
     "node-ipc": "^9.1.1",
     "opn": "^5.3.0",
     "ora": "^2.1.0",