javascript - 我如何判断我的 promise.all 是否并行运行？

Question

我有以下 Promise.all 示例。我想知道它在 lambda.invoke 方面是否“并行”运行？我如何测试某些东西是否并行运行？

引用此 thread

function get1(id) {
    return new Promise((resolve, reject) => {
        const params = {
            FunctionName: 'myLambda', // the lambda function we are going to invoke
            InvocationType: 'RequestResponse',
            Payload: { id },
        };

        lambda.invoke(params, (err, data) => {
            if (err) {
                reject(new Error('error'));
            } else {
                const result = JSON.parse(data.Payload);
                resolve(result);
            }
        });
    }).catch(e => Promise.resolve({ error: 'Error has occurred.' }));
}

exports.getDetails = list => Promise.all(list.map(get1))
    .then((response) => {
        return result;
    }).catch((error) => {
        console.log('oops ', error);
    });

Answer 1

你可以计算有多少 Action 已经开始但还没有完成:

  let running = 0;

  // Inside of the promise:
  running++;
  lambda.invoke(params, (err, data) => {
    running--;
    console.log(`lambda.invoked finished, ${running} tasks still running`);
  });

如果 invoke 是同步的，你会得到:

  lambda.invoked finished, 0 tasks still running
  lambda.invoked finished, 0 tasks still running
  lambda.invoked finished, 0 tasks still running

如果它是异步的，你会得到:

  lambda.invoked finished, 2 tasks still running
  lambda.invoked finished, 1 tasks still running
  lambda.invoked finished, 0 tasks still running