Swift3 GCD全局队列(global)的优先级

布满荆棘的人生 2022-07-15 11:26 426阅读 0赞

**Swift 3 在GCD的语法上改变了很多，更加贴近了swift的语法，而且关于队列的优先级也改变了不少。**

**原先的GCD只有四个优先级，high，default，low，background**

**然而现在的GCD有六个优先级，background，utility，default，userInitiated，userInteractive，unspecified**

**经过试验，得出了几个结论，**

**userInteractive的优先级最高，相当于high**

**background的优先级最低，相当于原来的background**

**default的优先级高于unspecified，userInitiated，utility**

**unspecified的优先级高于userInitiated，utility**

**userInitiated的优先级高于utility**

**userInteractive>default>unspecified>userInitiated>utility>background**

**另附实验代码，若有不正确的地方欢迎指正**

for i in 1...10 {
           DispatchQueue.global(qos: DispatchQoS.QoSClass.default).async {
               NSLog("DispatchQoS.QoSClass.default, %d", i)
           }
                
           DispatchQueue.global(qos: DispatchQoS.QoSClass.background).async {
               NSLog("DispatchQoS.QoSClass.background, %d", i)
           }
                
           DispatchQueue.global(qos: DispatchQoS.QoSClass.unspecified).async {
               NSLog("DispatchQoS.QoSClass.unspecified, %d", i)
           }
                
           DispatchQueue.global(qos: DispatchQoS.QoSClass.userInitiated).async {
               NSLog("DispatchQoS.QoSClass.userInitiated, %d", i)
           }
                
           DispatchQueue.global(qos: DispatchQoS.QoSClass.userInteractive).async {
               NSLog("DispatchQoS.QoSClass.userInteractive, %d", i)
           }
                
           DispatchQueue.global(qos: DispatchQoS.QoSClass.utility).async {
               NSLog("DispatchQoS.QoSClass.utility, %d", i)
           }
    }

**试验数据：**

2016-11-15 11:46:12.927070 GraphicsContext[2099:635166] DispatchQoS.QoSClass.userInteractive, 1
    2016-11-15 11:46:12.927363 GraphicsContext[2099:635166] DispatchQoS.QoSClass.userInteractive, 2
    2016-11-15 11:46:12.927407 GraphicsContext[2099:635171] DispatchQoS.QoSClass.userInteractive, 3
    2016-11-15 11:46:12.927490 GraphicsContext[2099:635166] DispatchQoS.QoSClass.userInteractive, 4
    2016-11-15 11:46:12.927674 GraphicsContext[2099:635166] DispatchQoS.QoSClass.userInteractive, 5
    2016-11-15 11:46:12.927780 GraphicsContext[2099:635166] DispatchQoS.QoSClass.userInteractive, 6
    2016-11-15 11:46:12.927868 GraphicsContext[2099:635172] DispatchQoS.QoSClass.userInteractive, 7
    2016-11-15 11:46:12.927871 GraphicsContext[2099:635166] DispatchQoS.QoSClass.userInteractive, 8
    2016-11-15 11:46:12.928016 GraphicsContext[2099:635172] DispatchQoS.QoSClass.userInteractive, 9
    2016-11-15 11:46:12.928138 GraphicsContext[2099:635166] DispatchQoS.QoSClass.userInteractive, 10
    2016-11-15 11:46:12.928719 GraphicsContext[2099:635113] DispatchQoS.QoSClass.default, 1
    2016-11-15 11:46:12.928817 GraphicsContext[2099:635166] DispatchQoS.QoSClass.unspecified, 1
    2016-11-15 11:46:12.928924 GraphicsContext[2099:635172] DispatchQoS.QoSClass.userInitiated, 1
    2016-11-15 11:46:12.929190 GraphicsContext[2099:635173] DispatchQoS.QoSClass.default, 2
    2016-11-15 11:46:12.929225 GraphicsContext[2099:635171] DispatchQoS.QoSClass.utility, 1
    2016-11-15 11:46:12.929723 GraphicsContext[2099:635174] DispatchQoS.QoSClass.unspecified, 2
    2016-11-15 11:46:12.930104 GraphicsContext[2099:635176] DispatchQoS.QoSClass.userInitiated, 2
    2016-11-15 11:46:12.930131 GraphicsContext[2099:635175] DispatchQoS.QoSClass.utility, 2
    2016-11-15 11:46:12.930641 GraphicsContext[2099:635177] DispatchQoS.QoSClass.default, 3
    2016-11-15 11:46:12.931705 GraphicsContext[2099:635179] DispatchQoS.QoSClass.unspecified, 3
    2016-11-15 11:46:12.931857 GraphicsContext[2099:635180] DispatchQoS.QoSClass.userInitiated, 3
    2016-11-15 11:46:12.932196 GraphicsContext[2099:635181] DispatchQoS.QoSClass.default, 4
    2016-11-15 11:46:12.932277 GraphicsContext[2099:635178] DispatchQoS.QoSClass.utility, 3
    2016-11-15 11:46:12.932779 GraphicsContext[2099:635183] DispatchQoS.QoSClass.unspecified, 4
    2016-11-15 11:46:12.932889 GraphicsContext[2099:635182] DispatchQoS.QoSClass.userInitiated, 4
    2016-11-15 11:46:12.933215 GraphicsContext[2099:635185] DispatchQoS.QoSClass.default, 5
    2016-11-15 11:46:12.933027 GraphicsContext[2099:635184] DispatchQoS.QoSClass.utility, 4
    2016-11-15 11:46:12.933423 GraphicsContext[2099:635113] DispatchQoS.QoSClass.unspecified, 5
    2016-11-15 11:46:12.933586 GraphicsContext[2099:635166] DispatchQoS.QoSClass.userInitiated, 5
    2016-11-15 11:46:12.933709 GraphicsContext[2099:635172] DispatchQoS.QoSClass.default, 6
    2016-11-15 11:46:12.933831 GraphicsContext[2099:635173] DispatchQoS.QoSClass.unspecified, 6
    2016-11-15 11:46:12.933976 GraphicsContext[2099:635174] DispatchQoS.QoSClass.userInitiated, 6
    2016-11-15 11:46:12.934095 GraphicsContext[2099:635176] DispatchQoS.QoSClass.default, 7
    2016-11-15 11:46:12.934242 GraphicsContext[2099:635177] DispatchQoS.QoSClass.unspecified, 7
    2016-11-15 11:46:12.934356 GraphicsContext[2099:635179] DispatchQoS.QoSClass.userInitiated, 7
    2016-11-15 11:46:12.934503 GraphicsContext[2099:635180] DispatchQoS.QoSClass.default, 8
    2016-11-15 11:46:12.934611 GraphicsContext[2099:635171] DispatchQoS.QoSClass.utility, 5
    2016-11-15 11:46:12.934701 GraphicsContext[2099:635175] DispatchQoS.QoSClass.utility, 6
    2016-11-15 11:46:12.937166 GraphicsContext[2099:635186] DispatchQoS.QoSClass.unspecified, 8
    2016-11-15 11:46:12.937476 GraphicsContext[2099:635188] DispatchQoS.QoSClass.userInitiated, 8
    2016-11-15 11:46:12.937521 GraphicsContext[2099:635187] DispatchQoS.QoSClass.utility, 7
    2016-11-15 11:46:12.937682 GraphicsContext[2099:635181] DispatchQoS.QoSClass.default, 9
    2016-11-15 11:46:12.937868 GraphicsContext[2099:635183] DispatchQoS.QoSClass.unspecified, 9
    2016-11-15 11:46:12.937987 GraphicsContext[2099:635182] DispatchQoS.QoSClass.userInitiated, 9
    2016-11-15 11:46:12.938110 GraphicsContext[2099:635185] DispatchQoS.QoSClass.default, 10
    2016-11-15 11:46:12.938262 GraphicsContext[2099:635113] DispatchQoS.QoSClass.unspecified, 10
    2016-11-15 11:46:12.938381 GraphicsContext[2099:635166] DispatchQoS.QoSClass.userInitiated, 10
    2016-11-15 11:46:12.938692 GraphicsContext[2099:635178] DispatchQoS.QoSClass.utility, 8
    2016-11-15 11:46:12.938837 GraphicsContext[2099:635184] DispatchQoS.QoSClass.utility, 9
    2016-11-15 11:46:12.941483 GraphicsContext[2099:635174] DispatchQoS.QoSClass.utility, 10
    2016-11-15 11:46:12.949181 GraphicsContext[2099:635115] DispatchQoS.QoSClass.background, 1
    2016-11-15 11:46:12.949734 GraphicsContext[2099:635115] DispatchQoS.QoSClass.background, 2
    2016-11-15 11:46:12.950257 GraphicsContext[2099:635115] DispatchQoS.QoSClass.background, 3
    2016-11-15 11:46:12.950775 GraphicsContext[2099:635115] DispatchQoS.QoSClass.background, 4
    2016-11-15 11:46:12.951348 GraphicsContext[2099:635115] DispatchQoS.QoSClass.background, 5
    2016-11-15 11:46:12.952512 GraphicsContext[2099:635115] DispatchQoS.QoSClass.background, 6
    2016-11-15 11:46:12.953108 GraphicsContext[2099:635115] DispatchQoS.QoSClass.background, 7
    2016-11-15 11:46:12.953659 GraphicsContext[2099:635115] DispatchQoS.QoSClass.background, 8
    2016-11-15 11:46:12.954176 GraphicsContext[2099:635115] DispatchQoS.QoSClass.background, 9
    2016-11-15 11:46:12.954890 GraphicsContext[2099:635115] DispatchQoS.QoSClass.background, 10