Question

我正在尝试设置一个我正在开发的应用程序，其中涉及录制HTML小部件（带有动画）并将其转换为mp4。在本地，效果很好。我让Nightmare Js处理屏幕截图，然后让FFMPEG将屏幕截图转换成mp4，在我的PC上大约需要90 s。

我正在通过托管服务将其设置在docker容器中，无法解决此问题。目前，我的测试脚本如下所示：

const Nightmare = require('nightmare')
const Xvfb = require('xvfb')

module.exports = function(app) {
  app.get('/api/nightmare', async (req, res) => {
    console.log('GET request to /api/nightmare')

    try {
      // Start xvfb and create our nightmare object
      const close = await xvfb()
      const nightmare = Nightmare({ executionTimeout: 1000 })

      const [err, result] = await poss(run(nightmare))
      if (err) {
        // Cleanup before throwing error
        await nightmare.end()
        await close()
        throw err
      }

      // shut'er down
      await nightmare.end()
      await close()
      res.status(200).send('Completed')
    } catch (error) {
      console.log(error)
      res.status(500).send(error)
    }
  })  
}

async function run(nightmare) {
  var data = {
    'id': '2OWBTMUL',
    'somedata': 'blah'
    // More data pulled from the database goes here
  }

  // Create folder to hold images
  var procName = new Date().getTime() + '_testing_' + data.id
  fs.mkdirSync(path.resolve(__dirname, '../processing/', procName))

  // URL to inject into webpage so the webpage can access the data
  var url = `http://example.com?` +
    `id=${data.id}&` +
    `somedata=${data.somedata}`

  console.log('Starting NightmareJs')
  await nightmare
    .viewport(1920, 1080)
    .goto('file:///' + path.resolve(__dirname, '../templates/example.html'))
    .evaluate(newUrl => {
      // Set url and get the page ready for recording
      url = new URL(newUrl)
      initiate()
      start()
      timeline.pause()
    }, url)
    .catch(error => { console.log(error) })

  // Take 200 screenshots (8s @ 25fps)
  var frames = 200
  for (var i = 0; i < frames; i++) {
    console.log('Taking screenshot ' + i)

    await nightmare
      .screenshot(path.resolve(__dirname, '../processing/', procName, 'screen_' + i + '.png'))
      .evaluate(shot => { timeline.seek((8 / 200) * shot) }, i)
      .catch(error => { console.log(error) })
  }

  console.log('Done.')
}

// xvfb wrapper
function xvfb(options) {
  var xvfb = new Xvfb(options)

  function close() {
    return new Promise((resolve, reject) => {
      xvfb.stop(err => (err ? reject(err) : resolve()))
    })
  }

  return new Promise((resolve, reject) => {
    xvfb.start(err => (err ? reject(err) : resolve(close)))
  })
}

// try/catch helper
async function poss(promise) {
  try {
    const result = await promise
    return [null, result]
  } catch (err) {
    return [err, null]
  }
}

一些环境细节：
Ubuntu 18.04.1
主管
节点8.12.0（已设置DEBUG = *）

问题：在大约17次循环后，噩梦引发了两个不同的错误。在我的nodejs-stderr.log文件中，我得到了

Taking screenshot x
Error: Evaluation timed out after 1000msec.  Are you calling done() or resolving your promises?

在评估中使用done（）回调或promise测试并没有改变任何东西，因此我保持了简单性

在我的nodejs-stdout.log文件中，每次成功循环我都会得到它

Mon, 19 Nov 2018 09:37:06 GMT nightmare:actions .screenshot()
Mon, 19 Nov 2018 09:37:06 GMT nightmare:log subscribing to browser window frames
Mon, 19 Nov 2018 09:37:06 GMT nightmare:log Highlighting page to trigger rendering.
Mon, 19 Nov 2018 09:37:06 GMT nightmare:log unsubscribing from browser window frames
Mon, 19 Nov 2018 09:37:07 GMT nightmare:actions .screenshot() captured with length 1092963
Mon, 19 Nov 2018 09:37:07 GMT nightmare:actions .evaluate() fn on the page
Mon, 19 Nov 2018 09:37:07 GMT nightmare queueing action "screenshot"
Mon, 19 Nov 2018 09:37:07 GMT nightmare queueing action "evaluate"
Mon, 19 Nov 2018 09:37:07 GMT nightmare running

然后经过17个左右的循环，我得到：

Mon, 19 Nov 2018 09:37:07 GMT nightmare:actions .screenshot()
Mon, 19 Nov 2018 09:37:07 GMT nightmare:log subscribing to browser window frames
Mon, 19 Nov 2018 09:37:07 GMT nightmare:log Highlighting page to trigger rendering.
Tue, 20 Nov 2018 02:11:43 GMT nightmare:log crashed [{},false]
Mon, 19 Nov 2018 09:37:12 GMT nightmare:log FrameManager timing out after 1000 ms with no new rendered frames
Mon, 19 Nov 2018 09:37:12 GMT nightmare:log unsubscribing from browser window frames
Mon, 19 Nov 2018 09:37:12 GMT nightmare:actions .screenshot() captured with length 0
Mon, 19 Nov 2018 09:37:12 GMT nightmare:actions .evaluate() fn on the page
Mon, 19 Nov 2018 09:37:13 GMT nightmare queueing action "screenshot"
Mon, 19 Nov 2018 09:37:13 GMT nightmare queueing action "evaluate"
Mon, 19 Nov 2018 09:37:13 GMT nightmare running

其余所有失败，没有crashed [{},false]消息。
在循环中删除.evaluate(shot => { timeline.seek((8 / 200) * shot) }, i)可解决此问题，但我需要这样做，否则就只是一动不动的视频！我尝试了单独的调用（而不是链接评估和屏幕截图），将.wait（200）放在了东西之间，但是我无法弄清楚这个问题，也找不到任何帮助。

Answer 1

原来是共享内存太小。我认为当图像全部加载完毕时，它超出了内存限制，Electron崩溃了。将共享内存从64MB升级到128MB后，问题得以解决。

噩梦Js评估在多次评估后超时

1 个答案: