Question

请在下面找到我编写的代码。如您所见，有一个名为waitForPromiseChunkToBeResolved的函数，该函数记录等待要解决的批次，解析承诺，然后最终记录该批次已全部解决。（程序从 main（）函数开始。）

每批承诺都需要2秒钟（因为这是我通过setTimeout硬编码的内容，请参见 promiseTakes2000ms ）。该程序目前总共需要2秒钟左右的时间，因为它并行执行所有40个诺言-但是我要实现的是它首先执行10个诺言，然后执行下一个10个诺言，依此类推。因此，该程序大约需要8秒钟的时间（一个包含40个承诺的数组执行4个块（每个10个承诺））。

我尝试使用第三方库，例如npmjs包async和p-queue。


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()

我希望程序花费8秒钟并输出以下内容：

=== 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

但是当前不正确的输出是：

=== 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

Answer 1

您可以在此处并行执行所有块：

 const waitForAllPromiseChunks = manyPromisesInChunksOfTen.map(async (batch) => {
    await waitForPromiseChunkToBeResolved(batch)
})

相反，只是一个接一个地循环：

 const results = [];

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

 return results;

如何分批执行承诺（先解决10个，然后再解决10个，依此类推）

1 个答案: