worker-farm: pass explicit execArgv to workers

Reviewed By: davidaurelio

Differential Revision: D5002197

fbshipit-source-id: 8f556626321963c103d38ec9865110a39f1a5109

packages/metro-bundler/src/JSTransformer/index.js

@@ -38,6 +38,7 @@ function makeFarm(worker, methods, timeout, maxConcurrentWorkers) {
   return workerFarm(
     {
       autoStart: true,
+      execArgv: [],
       maxConcurrentCallsPerWorker: 1,
       maxConcurrentWorkers,
       maxCallsPerWorker: MAX_CALLS_PER_WORKER,

packages/metro-bundler/src/worker-farm/lib/farm.js

@@ -27,7 +27,7 @@ const extend                  = require('xtend')
     , ProcessTerminatedError  = require('errno').create('ProcessTerminatedError')
     , MaxConcurrentCallsError = require('errno').create('MaxConcurrentCallsError')
 
-function Farm (options: {}, path: string) {
+function Farm (options: {+execArgv: Array<string>}, path: string) {
   this.options     = extend(DEFAULT_OPTIONS, options)
   this.path        = path
   this.activeCalls = 0
@@ -108,7 +108,7 @@ Farm.prototype.onExit = function (childId) {
 Farm.prototype.startChild = function () {
   this.childId++
 
-  var forked = fork(this.path)
+  var forked = fork(this.path, {execArgv: this.options.execArgv})
     , id     = this.childId
     , c      = {
           send        : forked.send

packages/metro-bundler/src/worker-farm/lib/fork.js

@@ -14,10 +14,11 @@
 const childProcess = require('child_process');
 const childModule = require.resolve('./child/index');
 
-function fork(forkModule: string) {
+function fork(forkModule: string, options: {|+execArgv: Array<string>|}) {
   const child = childProcess.fork(childModule, {
     env: process.env,
     cwd: process.cwd(),
+    execArgv: options.execArgv,
   });
 
   child.send({module: forkModule});

packages/metro-bundler/src/worker-farm/lib/index.js

@@ -14,7 +14,11 @@ const Farm = require('./farm')
 
 var farms = [] // keep record of farms so we can end() them if required
 
-function farm(options: {}, path: string, methods: Array<string>): {[name: string]: Function} {
+function farm(
+  options: {+execArgv: Array<string>},
+  path: string,
+  methods: Array<string>,
+): {[name: string]: Function} {
   var f   = new Farm(options, path)
     , api = f.setup(methods)