NodeJS Promise 全部从任务队列中获取所有承诺

问题描述

我正在尝试创建一个函数，该函数将获取一组 promise 并分块执行它们。

这里我有一个我写的函数的例子，它应该能完成我想要的。但是发生的事情是所有的承诺都已经在第一个 promise.all 之后执行了。 nodeJS 调试器显示它按我希望的那样工作。但是我可以在whireshark中看到所有请求都是在第一个块之后发送的。

const reqs = [...Array(10)].map(() => () => axios.post('http://localhost:7000/test',{}))


const handleChunks = (reqs) => {
    const chunks = []
    const chunkSize = 5
    for (let i = 0; i < reqs.length; i += chunkSize) {
      chunks.push(reqs.slice(i,i + chunkSize))
    }
    chunks.reduce(async (acc,chunk) => {
      const chunkToPromise = chunk.map((chunkFunc) => chunkFunc())
      return Promise.all(chunkToPromise).then(async (result) => {
          acc = await acc
          acc.push(result)
          return acc
      })
    },Promise.resolve([]))
}

在我看来，我创建的所有 Promise 都已经在任务队列中声明了自己，而 Promise.all 并没有真正接受你给他的东西，而是任务队列中的所有承诺>

有人知道如何处理这种问题吗？

编辑：我发现在客户端上的工作方式相同......

解决方法

这里有三个方面，对 Promise 进行分块，运行分块，并等待它们全部完成。让我们创建一些助手：

// NOTE: works but probably not optimal. I fired this off the top of my head,// for something like this in production I'd use a library function from
// lodash or ramda or something.
const partition = (n,xs) => {
  const results = [];
  let i = k = 0;
  while (i < xs.length) {
    results.push([]);
    while (k < n) {
      if (i === xs.length) break;
      results[results.length - 1].push(xs[i]);
      i++;
      k++;
    }
    k = 0;
  }
  return results; 
};

// This will make the requests from the passed in array and
// wait for them all to finish. Note that unlike Promise.all
// allSettled will not bail early if you get a rejection.
const runPromiseFns = async (ps) => Promise.allSettled(ps.map(x => x()));

// This will take an array of arrays of Promise generating functions
// and wait for each sub-array to settle before moving on
// to the next one.
const runChunks = async (chunks) => {
  for (let chunk of chunks) {
    await runPromiseFns(chunk);
  }

  return;
};

太好了。现在：

// Array of request thunks from your original code
const reqs = [...Array(10)].map(() => () => axios.post('http://localhost:7000/test',{}));

// Break into chunks of 5
const chunks = partition(5,reqs);

// Run through the execution pipe. Here allDone is a
// Promise you can .then or await somewhere else.
const allDone = runChunks(chunks);

const promiseAllFn = (pollingRequests) => Promise.all(pollingRequests.map((pollingRequest) => callApi(pollingRequest)));

    chunk(Object.values(subRegister),4).reduce(
        (prev,pollingRequests) => prev.then(() => promiseAllFn(pollingRequests)),Promise.resolve('start')
    );

async-await chunks javascript