文档建议反馈控制台
首页
学习
活动
专区
圈层
工具
MCP广场
文章/答案/技术大牛
发布
社区首页 >问答首页 >如何分批执行承诺(先解析10，然后再执行10，等等)

问如何分批执行承诺(先解析10，然后再执行10，等等)
EN

Stack Overflow用户
提问于 2019-08-17 14:25:17
回答 1查看 1.6K关注 0票数 2

请在下面找到我所写的代码。如您所见，有一个名为waitForPromiseChunkToBeResolved的函数，它记录等待批处理被解析，解析一个承诺数组，然后最终记录该批处理已经全部解析。(程序从main()函数开始。)

每一批承诺都需要2秒的时间(因为这是我通过setTimeout硬编码的，参见promiseTakes2000ms)。这个程序目前总共需要大约2秒，因为它并行执行所有40个承诺，但我想要实现的是，它首先执行10个承诺，然后再执行10个承诺，以此类推。因此，程序应该花费大约8秒(由40个承诺组成的数组执行4块10项承诺)。

我试过使用第三方库，比如npmjs包、异步包和p队列。

代码语言：javascript
复制
const promiseTakes2000ms = (succeeds) => {
    return new Promise((resolve, reject) => {
        setTimeout(() => {
            if (succeeds) {
                resolve("Success / 2000ms wait")
            } else {
                reject("Failure / 2000ms wait")
            }
        }, 2000)
    })
}

const reflectPromise = (promise) => {
    return promise.then((promiseResult) => {
        return {
            promiseResult,
            success: true
        }
    }).catch((error) => {
            return {
                error,
                success: false
            }
    })
}

const sliceArrayIntoChunks = (arr, chunkSize) => {
    const chunks = []
    let i = 0
    const n = arr.length

    while (i < n) {
      chunks.push(arr.slice(i, i += chunkSize))
    }

    return chunks
}

const waitForPromiseChunkToBeResolved = (promiseChunk) => {
    console.log("=== Waiting for the batch to be resolved")
    return Promise.all(promiseChunk).then((resolvedChunkResults) => {
        console.log(resolvedChunkResults)
        console.log("*** The batch has been all resolved")
        return resolvedChunkResults
    })
}


const executePromisesBatchAfterBatch = async (promises) => {
    const promisesReflected = promises.map(reflectPromise)
    const manyPromisesInChunksOfTen = sliceArrayIntoChunks(promisesReflected, 10)
    const waitForAllPromiseChunks = manyPromisesInChunksOfTen.map(async (batch) => {
        await waitForPromiseChunkToBeResolved(batch)
    })
    await Promise.all(waitForAllPromiseChunks)
}

const main = async () => {
    const resolvingPromises = new Array(20).fill(promiseTakes2000ms(true))
    const rejectingPromises = new Array(20).fill(promiseTakes2000ms(false))
    const manyPromises = resolvingPromises.concat(rejectingPromises)
    await executePromisesBatchAfterBatch(manyPromises)
}

main()

我预计程序将花费8秒，并输出以下内容：

代码语言：javascript
复制
=== Waiting for the batch to be resolved
[ { promiseResult: 'Success / 2000ms wait', success: true },
  { promiseResult: 'Success / 2000ms wait', success: true },
  { promiseResult: 'Success / 2000ms wait', success: true },
  { promiseResult: 'Success / 2000ms wait', success: true },
  { promiseResult: 'Success / 2000ms wait', success: true },
  { promiseResult: 'Success / 2000ms wait', success: true },
  { promiseResult: 'Success / 2000ms wait', success: true },
  { promiseResult: 'Success / 2000ms wait', success: true },
  { promiseResult: 'Success / 2000ms wait', success: true },
  { promiseResult: 'Success / 2000ms wait', success: true } ]
*** The batch has been all resolved
=== Waiting for the batch to be resolved
[ { promiseResult: 'Success / 2000ms wait', success: true },
  { promiseResult: 'Success / 2000ms wait', success: true },
  { promiseResult: 'Success / 2000ms wait', success: true },
  { promiseResult: 'Success / 2000ms wait', success: true },
  { promiseResult: 'Success / 2000ms wait', success: true },
  { promiseResult: 'Success / 2000ms wait', success: true },
  { promiseResult: 'Success / 2000ms wait', success: true },
  { promiseResult: 'Success / 2000ms wait', success: true },
  { promiseResult: 'Success / 2000ms wait', success: true },
  { promiseResult: 'Success / 2000ms wait', success: true } ]
*** The batch has been all resolved
=== Waiting for the batch to be resolved
[ { promiseResult: 'Success / 2000ms wait', success: true },
  { promiseResult: 'Success / 2000ms wait', success: true },
  { promiseResult: 'Success / 2000ms wait', success: true },
  { promiseResult: 'Success / 2000ms wait', success: true },
  { promiseResult: 'Success / 2000ms wait', success: true },
  { promiseResult: 'Success / 2000ms wait', success: true },
  { promiseResult: 'Success / 2000ms wait', success: true },
  { promiseResult: 'Success / 2000ms wait', success: true },
  { promiseResult: 'Success / 2000ms wait', success: true },
  { promiseResult: 'Success / 2000ms wait', success: true } ]
*** The batch has been all resolved
=== Waiting for the batch to be resolved
[ { promiseResult: 'Success / 2000ms wait', success: true },
  { promiseResult: 'Success / 2000ms wait', success: true },
  { promiseResult: 'Success / 2000ms wait', success: true },
  { promiseResult: 'Success / 2000ms wait', success: true },
  { promiseResult: 'Success / 2000ms wait', success: true },
  { promiseResult: 'Success / 2000ms wait', success: true },
  { promiseResult: 'Success / 2000ms wait', success: true },
  { promiseResult: 'Success / 2000ms wait', success: true },
  { promiseResult: 'Success / 2000ms wait', success: true },
  { promiseResult: 'Success / 2000ms wait', success: true } ]
*** The batch has been all resolved

但当前的、不正确的输出是：

代码语言：javascript
复制
=== Waiting for the batch to be resolved
=== Waiting for the batch to be resolved
=== Waiting for the batch to be resolved
=== Waiting for the batch to be resolved
[ { promiseResult: 'Success / 2000ms wait', success: true },
  { promiseResult: 'Success / 2000ms wait', success: true },
  { promiseResult: 'Success / 2000ms wait', success: true },
  { promiseResult: 'Success / 2000ms wait', success: true },
  { promiseResult: 'Success / 2000ms wait', success: true },
  { promiseResult: 'Success / 2000ms wait', success: true },
  { promiseResult: 'Success / 2000ms wait', success: true },
  { promiseResult: 'Success / 2000ms wait', success: true },
  { promiseResult: 'Success / 2000ms wait', success: true },
  { promiseResult: 'Success / 2000ms wait', success: true } ]
*** The batch has been all resolved
[ { promiseResult: 'Success / 2000ms wait', success: true },
  { promiseResult: 'Success / 2000ms wait', success: true },
  { promiseResult: 'Success / 2000ms wait', success: true },
  { promiseResult: 'Success / 2000ms wait', success: true },
  { promiseResult: 'Success / 2000ms wait', success: true },
  { promiseResult: 'Success / 2000ms wait', success: true },
  { promiseResult: 'Success / 2000ms wait', success: true },
  { promiseResult: 'Success / 2000ms wait', success: true },
  { promiseResult: 'Success / 2000ms wait', success: true },
  { promiseResult: 'Success / 2000ms wait', success: true } ]
*** The batch has been all resolved
[ { error: 'Failure / 2000ms wait', success: false },
  { error: 'Failure / 2000ms wait', success: false },
  { error: 'Failure / 2000ms wait', success: false },
  { error: 'Failure / 2000ms wait', success: false },
  { error: 'Failure / 2000ms wait', success: false },
  { error: 'Failure / 2000ms wait', success: false },
  { error: 'Failure / 2000ms wait', success: false },
  { error: 'Failure / 2000ms wait', success: false },
  { error: 'Failure / 2000ms wait', success: false },
  { error: 'Failure / 2000ms wait', success: false } ]
*** The batch has been all resolved
[ { error: 'Failure / 2000ms wait', success: false },
  { error: 'Failure / 2000ms wait', success: false },
  { error: 'Failure / 2000ms wait', success: false },
  { error: 'Failure / 2000ms wait', success: false },
  { error: 'Failure / 2000ms wait', success: false },
  { error: 'Failure / 2000ms wait', success: false },
  { error: 'Failure / 2000ms wait', success: false },
  { error: 'Failure / 2000ms wait', success: false },
  { error: 'Failure / 2000ms wait', success: false },
  { error: 'Failure / 2000ms wait', success: false } ]
*** The batch has been all resolved
javascript
EN

回答 1

Stack Overflow用户

回答已采纳

发布于 2019-08-17 14:28:43

在这里并行执行所有块：

代码语言：javascript
复制
 const waitForAllPromiseChunks = manyPromisesInChunksOfTen.map(async (batch) => {
    await waitForPromiseChunkToBeResolved(batch)
})

相反，只需一个又一个地循环：

代码语言：javascript
复制
 const results = [];

  for(const batch of manyPromisesInChunksOfTen)
    results.push(...await waitForPromiseChunkToBeResolved(batch));

 return results;
票数 2
EN
页面原文内容由Stack Overflow提供。腾讯云小微IT领域专用引擎提供翻译支持
原文链接：

https://stackoverflow.com/questions/57537154

复制
相关文章

相似问题

领券

腾讯云开发者

扫码关注腾讯云开发者

扫码关注腾讯云开发者

领取腾讯云代金券

热门产品

热门推荐

更多推荐

Copyright © 2013 - 2026 Tencent Cloud. All Rights Reserved. 腾讯云 版权所有 

深圳市腾讯计算机系统有限公司 ICP备案/许可证号：粤B2-20090059 粤公网安备44030502008569号

腾讯云计算（北京）有限责任公司 京ICP证150476号 |  京ICP备11018762号

问题归档专栏文章快讯文章归档关键词归档开发者手册归档开发者手册 Section 归档