我正在努力实现这一点: 我有四个数组和一个可以改变它们的函数“calculateResult”。这些数组的元素个数为 2^n,其中 n 是用户定义的值。该函数在循环中调用(例如,在实际项目中,迭代次数可以是 2^10)。 然后将数组分成多个部分(在实际项目中,部分数量 = 处理器数量)和“calculateResult”在此部分范围内并行。
我需要的具体情况(数组计数 = 2^10 = 1024,零件数 = 4):
import Foundation
func calculateResult(inRange calculationRange: CountableClosedRange<Int>) -> (ArraySlice<Double>, ArraySlice<Double>, ArraySlice<Double>, ArraySlice<Double>) {
var array1 = Array(repeating: 0.0, count: calculationRange.count)
var array2 = Array(repeating: 0.0, count: calculationRange.count)
var array3 = Array(repeating: 0.0, count: calculationRange.count)
var array4 = Array(repeating: 0.0, count: calculationRange.count)
var iRes = 0
for i in calculationRange {
array1[iRes] = Double(i * 1)
array2[iRes] = Double(i * 10)
array3[iRes] = Double(i * 100)
array4[iRes] = Double(i * 1000)
iRes += 1
}
return (ArraySlice(array1), ArraySlice(array2), ArraySlice(array3), ArraySlice(array4))
}
var result1 = Array(repeating: 0.0, count: 1024)
var result2 = Array(repeating: 0.0, count: 1024)
var result3 = Array(repeating: 0.0, count: 1024)
var result4 = Array(repeating: 0.0, count: 1024)
func calculateResConcurrent() {
let operationQueue = OperationQueue.init()
let op1 = BlockOperation.init {
print("Operation \(0)...")
(result1[0...255], result2[0...255], result3[0...255], result4[0...255]) = calculateResult(inRange: 0...255)
print("Operation \(0) DONE")
}
let op2 = BlockOperation.init {
print("Operation \(1)...")
(result1[256...511], result2[256...511], result3[256...511], result4[256...511]) = calculateResult(inRange: 256...511)
print("Operation \(1) DONE")
}
let op3 = BlockOperation.init {
print("Operation \(2)...")
(result1[512...767], result2[512...767], result3[512...767], result4[512...767]) = calculateResult(inRange: 512...767)
print("Operation \(2) DONE")
}
let op4 = BlockOperation.init {
print("Operation \(3)...")
(result1[768...1023], result2[768...1023], result3[768...1023], result4[768...1023]) = calculateResult(inRange: 768...1023)
print("Operation \(3) DONE")
}
operationQueue.addOperations([op1, op2, op3, op4], waitUntilFinished: true)
}
let numberOfIterations = 200
for i in 0...numberOfIterations {
print("\nMain iteration \(i) of \(numberOfIterations)")
calculateResConcurrent()
}
print("")
print(result1.last!, result2.last!, result3.last!, result4.last!) //Correct result is: (1023.0, 10230.0, 102300.0, 1023000.0)
我运行它,有时它崩溃并出现错误:“ fatal error :UnsafeMutablePointer.deinitialize with negative count”或返回错误结果。 请帮我找出错误并意识到这一点 :-) 我是 swift 的新手。
最佳答案
您最终可以做的是引入一个 DispatchQueue
以同步写入数组,并通过 BlockOperation
继续并发运行您的其余逻辑,因此您的功能可能是:
let queue = DispatchQueue(label: "syncQueue")
func calculateResConcurrent() {
let operationQueue = OperationQueue.init()
operationQueue.maxConcurrentOperationCount = 4
let ops:[BlockOperation] = [0...255, 256...511, 512...767, 768...1023].map { range in
let op = BlockOperation.init(block: {
let res = calculateResult(inRange: range) // concurrent
queue.sync(execute: { // synchronous
result1.replaceSubrange(range, with: res.0)
result2.replaceSubrange(range, with: res.1)
result3.replaceSubrange(range, with: res.2)
result4.replaceSubrange(range, with: res.3)
})
print("Operation \(range) finished")
})
return op
}
operationQueue.addOperations(ops, waitUntilFinished: true)
}
关于ios - 如何并发更新数组?,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/48780018/