iOS GCD全局隊列優先級都是0.5

我遇到的問題是爲什麼下面的代碼打印出來的優先級是一樣的？爲什麼是這樣？非常感謝你。iOS GCD全局隊列優先級都是0.5

print("main:\(Thread.current)") 
    print("thread main priorities:\(Thread.current.threadPriority)") 

    DispatchQueue.global(qos: .utility).async { 
     print("utility:\(Thread.current)") 
     print("thread utility priorities:\(Thread.current.threadPriority)") 
    } 

    DispatchQueue.global(qos: .background).async { 
     print("background:\(Thread.current)") 
     print("thread background priorities:\(Thread.current.threadPriority)") 
    } 

    DispatchQueue.global(qos: .userInteractive).async { 
     print("userInteractive:\(Thread.current)") 
     print("thread userInteractive priorities:\(Thread.current.threadPriority)") 
    } 

    DispatchQueue.global(qos: .userInitiated).async { 
     print("userInitiated:\(Thread.current)") 
     print("thread userInitiated priorities:\(Thread.current.threadPriority)") 
    }

日誌：

主：{數= 1，姓名=主} 螺紋主要優先：0.5

userInteractive：{數= 3，名稱=（空）}

實用程序：{number = 5，name =（null）}

背景：{number = 6，name =（null）}

個

螺紋userInteractive優先級：0.5

用戶引發：{數= 4，名稱=（空）}

螺紋效用優先級：0.5

螺紋背景優先級：0.5

螺紋用戶引發的優先級： 0.5

來源

2017-06-04 J.Deo

正如你可以在文檔中看到：

@available(iOS 4.0, *) 
open var threadPriority: Double // To be deprecated; use qualityOfService below

threadPriority已棄用。另外，Apple的GCD團隊在線程隊列主題上已經非常清楚。 GCD將爲您管理線程。隊列優先級不是線程優先級。看看這個例子，這是你在這裏發佈的代碼，我剛剛添加了「qos_class_self（）。rawValue」，這實際上應該如何測試QoS，而不是使用「threadPriority」。

print("main:\(Thread.current), Thread main priorities:\(Thread.current.threadPriority), QoS: \(qos_class_self().rawValue)") 

DispatchQueue.global(qos: .utility).async { 
    print("utility:\(Thread.current), Thread utility priorities:\(Thread.current.threadPriority), QoS: \(qos_class_self().rawValue)") 
} 

DispatchQueue.global(qos: .background).async { 
    print("background:\(Thread.current), Thread background priorities:\(Thread.current.threadPriority), QoS: \(qos_class_self().rawValue)") 
} 

DispatchQueue.global(qos: .userInteractive).async { 
    print("userInteractive:\(Thread.current), Thread userInteractive priorities:\(Thread.current.threadPriority), QoS: \(qos_class_self().rawValue)") 
} 

DispatchQueue.global(qos: .userInitiated).async { 
    print("userInitiated:\(Thread.current), Thread userInitiated priorities:\(Thread.current.threadPriority), QoS: \(qos_class_self().rawValue)") 
}

我也結合每封版畫所以它們不會在日誌中的不同線路加擾。這表明您保持了QoS，而不推薦使用threadPriority。

main:<NSThread: 0x6100000762c0>{number = 1, name = main}, Thread main priorities:0.5, QoS: 33 
userInteractive:<NSThread: 0x610000261fc0>{number = 4, name = (null)}, Thread userInteractive priorities:0.5, QoS: 33 
utility:<NSThread: 0x618000079100>{number = 3, name = (null)}, Thread utility priorities:0.5, QoS: 17 
userInitiated:<NSThread: 0x608000078380>{number = 5, name = (null)}, Thread userInitiated priorities:0.5, QoS: 25 
background:<NSThread: 0x610000262000>{number = 6, name = (null)}, Thread background priorities:0.5, QoS: 9

因此，在結束時，帶走的是不去想在主題方面，而且在隊列中，其服務質量的角度考慮，並知道GCD將管理線程爲您服務。與隊列中出現GCD之前我們習慣的概念截然不同。

來源

2017-06-05 03:15:51 zumzum

iOS GCD全局隊列優先級都是0.5

回答

相關問題