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| const { spawn, spawnSync } = require('child_process'); | |
| const { promisify } = require('util'); | |
| const { Semaphore } = require('await-semaphore'); | |
| const spawnAsync = promisify(spawn); | |
| async function go() { | |
| console.log("===SYNC==="); | |
| for (let i = 0; i < 10; i++) { | |
| let result = spawnSync('node', ['sayhi.js', i], { shell: true }); | |
| console.log(`${result.output}`); | |
| } | |
| console.log("===ASYNC==="); | |
| let promises = [] | |
| for (i = 0; i < 10; i++) { | |
| let promise = new Promise((res, rej) => { | |
| let childProcess = spawn('node', ['sayhi.js', i], { shell: true }); | |
| let stdOut = ''; | |
| let stdErr = ''; | |
| childProcess.on('close', (code) => res({code, stdOut, stdErr})); | |
| childProcess.stdout.on('data', (data) => stdOut = stdOut + data.toString()); | |
| childProcess.stderr.on('data', (err) => stdErr = stdErr + data.toString()); | |
| }); | |
| promises.push(promise); | |
| } | |
| try { | |
| console.log("awaiting parallel execution of", promises.length, "processes"); | |
| const results = await Promise.all(promises); | |
| console.log(results); | |
| for (let item of results) { | |
| console.log(item.stdOut); | |
| } | |
| } catch (ex) { | |
| console.log("ERROR", ex); | |
| } | |
| console.log("WITH POOLING") | |
| let commands = [] | |
| for (i = 0; i < 10; i++) | |
| { | |
| commands.push(['node', ['sayhi.js', i]]); | |
| } | |
| const semaphroe = new Semaphore(2); | |
| poolPromises = []; | |
| let liveCount = 0; | |
| for (const command of commands) { | |
| let promise = new Promise(async (res, rej) => { | |
| console.log("LiveCount: ", liveCount); | |
| let releaseSemaphore = await semaphroe.acquire(); | |
| liveCount++; | |
| console.log("LiveCount: ", liveCount); | |
| let childProcess = spawn(command[0], command[1], { shell: true }); | |
| let stdOut = ''; | |
| let stdErr = ''; | |
| childProcess.on('close', (code) => { | |
| releaseSemaphore(); | |
| console.log("LiveCount: ", liveCount); | |
| liveCount--; | |
| res({code, stdOut, stdErr}) | |
| }); | |
| childProcess.stdout.on('data', (data) => console.log(data.toString())); | |
| childProcess.stderr.on('data', (err) => console.log(err.toString())); | |
| console.log("LiveCount: ", liveCount); | |
| }); | |
| poolPromises.push(promise); | |
| } | |
| const poolPromiseResult = await Promise.all(poolPromises); | |
| console.log(poolPromiseResult); | |
| console.log("All done!"); | |
| } | |
| go(); |
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