您的位置：首页 > 移动开发 > IOS开发

iOS gcd 串行，并行，同步，异步代码研究

2017-02-10 18:14 621 查看
参考文章：

p.p1{margin:0.0px0.0px0.0px0.0px;font:13.0pxMenlo;color:#527eff}
span.s1{}
http://www.cnblogs.com/mddblog/p/4767559.html

重要结论：

p.p1{margin:0.0px0.0px0.0px0.0px;font:13.0px"PingFangSC";color:#4bd157}
p.p2{margin:0.0px0.0px0.0px0.0px;font:13.0pxMenlo;color:#4bd157;min-height:15.0px}
span.s1{font:13.0pxMenlo}
span.s2{}
　　1）串行队列，同步执行-----串行队列意味着顺序执行，同步执行意味着不开启线程（在当前线程执行）

　　2）串行队列,异步执行-----串行队列意味着任务顺序执行，异步执行说明要开线程,（如果开多个线程的话，不能保证串行队列顺序执行，所以只开一个线程）

　　3）并行队列,异步执行-----并行队列意味着执行顺序不确定，异步执行意味着会开启线程，而并行队列又允许不按顺序执行，所以系统为了提高性能会开启多个线程，来队列取任务（队列中任务取出仍然是顺序取出的，只是线程执行无序）。

　　4）并行队列,同步执行-----同步执行意味着不开线程,则肯定是顺序执行

分别进行验证

串行同步

//串行同步
-(void)test_queue_serial_sync
{
NSLog(@"串行同步");
dispatch_queue_tqueue=dispatch_queue_create("com.demo.001",DISPATCH_QUEUE_SERIAL);
NSLog(@"mainthread:%p",[NSThreadmainThread]);
dispatch_sync(queue,^{
NSLog(@"1thread:%p",[NSThreadcurrentThread]);
});
dispatch_sync(queue,^{
NSLog(@"2thread:%p",[NSThreadcurrentThread]);
});
dispatch_sync(queue,^{
NSLog(@"3thread:%p",[NSThreadcurrentThread]);
});
dispatch_sync(queue,^{
NSLog(@"4thread:%p",[NSThreadcurrentThread]);
});
}
//结果

2017-02-1018:00:21.991383RXVerifyExample[4927:2465789]串行同步
2017-02-1018:00:21.991636RXVerifyExample[4927:2465789]mainthread:0x17406cb00
2017-02-1018:00:21.992020RXVerifyExample[4927:2465789]1thread:0x17406cb00
2017-02-1018:00:21.992097RXVerifyExample[4927:2465789]2thread:0x17406cb00
2017-02-1018:00:21.992165RXVerifyExample[4927:2465789]3thread:0x17406cb00
2017-02-1018:00:21.992230RXVerifyExample[4927:2465789]4thread:0x17406cb00



结论：

串行同步，不创建任何新的线程，因为是在主线程中执行这个方法的，所以，同步方法都在主线程。

并行同步

//并行同步
-(void)test_queue_concurrent_sync
{
NSLog(@"并行同步");
dispatch_queue_tqueue=dispatch_queue_create("com.demo.002",DISPATCH_QUEUE_CONCURRENT);
NSLog(@"mainthread:%p",[NSThreadmainThread]);
dispatch_sync(queue,^{
NSLog(@"1thread:%p",[NSThreadcurrentThread]);
});
dispatch_sync(queue,^{
NSLog(@"2thread:%p",[NSThreadcurrentThread]);
});
dispatch_sync(queue,^{
NSLog(@"3thread:%p",[NSThreadcurrentThread]);
});
dispatch_sync(queue,^{
NSLog(@"4thread:%p",[NSThreadcurrentThread]);
});
}
//结果：

2017-02-1018:04:33.107907RXVerifyExample[4930:2467403]并行同步
2017-02-1018:04:33.108053RXVerifyExample[4930:2467403]mainthread:0x174066600
2017-02-1018:04:33.108121RXVerifyExample[4930:2467403]1thread:0x174066600
2017-02-1018:04:33.108177RXVerifyExample[4930:2467403]2thread:0x174066600
2017-02-1018:04:33.108219RXVerifyExample[4930:2467403]3thread:0x174066600
2017-02-1018:04:33.108259RXVerifyExample[4930:2467403]4thread:0x174066600



结论：跟串行同步是一样的。

串行异步1

//串行异步1
-(void)test_queue_serial_async1
{
NSLog(@"串行异步方法1");
dispatch_queue_tqueue=dispatch_queue_create("com.demo.0031",DISPATCH_QUEUE_SERIAL);
NSLog(@"mainthread:%p",[NSThreadmainThread]);
dispatch_async(queue,^{
NSLog(@"1thread:%p",[NSThreadcurrentThread]);
});
dispatch_async(queue,^{
NSLog(@"2thread:%p",[NSThreadcurrentThread]);
});
dispatch_async(queue,^{
NSLog(@"3thread:%p",[NSThreadcurrentThread]);
});
dispatch_async(queue,^{
NSLog(@"4thread:%p",[NSThreadcurrentThread]);
});
}
//结果：
2017-02-1018:06:15.124048RXVerifyExample[4932:2468052]串行异步方法1
2017-02-1018:06:15.124244RXVerifyExample[4932:2468052]mainthread:0x174076a40
2017-02-1018:06:15.125490RXVerifyExample[4932:2468084]1thread:0x174271800
2017-02-1018:06:15.125574RXVerifyExample[4932:2468084]2thread:0x174271800
2017-02-1018:06:15.125643RXVerifyExample[4932:2468084]3thread:0x174271800
2017-02-1018:06:15.125710RXVerifyExample[4932:2468084]4thread:0x174271800


串行异步2

//串行异步2
-(void)test_queue_serial_async2
{
NSLog(@"串行异步方法2");
dispatch_queue_tqueue=dispatch_queue_create("com.demo.0032",DISPATCH_QUEUE_SERIAL);
NSLog(@"mainthread:%p",[NSThreadmainThread]);
dispatch_async(queue,^{
NSLog(@"1thread:%p",[NSThreadcurrentThread]);
});
dispatch_async(queue,^{
NSLog(@"2thread:%p",[NSThreadcurrentThread]);
});
dispatch_async(queue,^{
[NSThreadsleepForTimeInterval:4.1];
NSLog(@"3thread:%p",[NSThreadcurrentThread]);
});
dispatch_async(queue,^{
[NSThreadsleepForTimeInterval:3.1];
NSLog(@"4thread:%p",[NSThreadcurrentThread]);
});
}
//结果
2017-02-1018:08:16.478508RXVerifyExample[4935:2468827]串行异步方法2
2017-02-1018:08:16.478611RXVerifyExample[4935:2468827]mainthread:0x170072380
2017-02-1018:08:16.479034RXVerifyExample[4935:2468869]1thread:0x174264240
2017-02-1018:08:16.479069RXVerifyExample[4935:2468869]2thread:0x174264240
2017-02-1018:08:20.584321RXVerifyExample[4935:2468869]3thread:0x174264240
2017-02-1018:08:23.689611RXVerifyExample[4935:2468869]4thread:0x174264240


结论：

串行异步只创建一个新的线程

并行异步1

//并行异步1
-(void)test_queue_concurrent_async1
{
NSLog(@"并行异步方法1");
dispatch_queue_tqueue=dispatch_queue_create("com.demo.0041",DISPATCH_QUEUE_CONCURRENT);
NSLog(@"mainthread:%p",[NSThreadmainThread]);
dispatch_async(queue,^{
NSLog(@"1thread:%p",[NSThreadcurrentThread]);
});
dispatch_async(queue,^{
NSLog(@"2thread:%p",[NSThreadcurrentThread]);
});
dispatch_async(queue,^{
NSLog(@"3thread:%p",[NSThreadcurrentThread]);
});
dispatch_async(queue,^{
NSLog(@"4thread:%p",[NSThreadcurrentThread]);
});
}

//结果
2017-02-1018:09:25.692681RXVerifyExample[4937:2469287]并行异步方法1
2017-02-1018:09:25.692880RXVerifyExample[4937:2469287]mainthread:0x174073000
2017-02-1018:09:25.693828RXVerifyExample[4937:2469323]1thread:0x174267d00
2017-02-1018:09:25.693916RXVerifyExample[4937:2469323]2thread:0x174267d00
2017-02-1018:09:25.693988RXVerifyExample[4937:2469323]3thread:0x174267d00
2017-02-1018:09:25.694056RXVerifyExample[4937:2469323]4thread:0x174267d00


并行异步2

//并行异步2
-(void)test_queue_concurrent_async2
{
NSLog(@"并行异步方法2");
dispatch_queue_tqueue=dispatch_queue_create("com.demo.0042",DISPATCH_QUEUE_CONCURRENT);
NSLog(@"mainthread:%p",[NSThreadmainThread]);
dispatch_async(queue,^{
NSLog(@"1thread:%p",[NSThreadcurrentThread]);
});
dispatch_async(queue,^{
NSLog(@"2thread:%p",[NSThreadcurrentThread]);
});
dispatch_async(queue,^{
[NSThreadsleepForTimeInterval:4.1];
NSLog(@"3thread:%p",[NSThreadcurrentThread]);
});
dispatch_async(queue,^{
[NSThreadsleepForTimeInterval:3.1];
NSLog(@"4thread:%p",[NSThreadcurrentThread]);
});
}
//结果
2017-02-1018:10:27.262009RXVerifyExample[4940:2469782]并行异步方法2
2017-02-1018:10:27.262213RXVerifyExample[4940:2469782]mainthread:0x17406e080
2017-02-1018:10:27.263710RXVerifyExample[4940:2469821]1thread:0x174262e80
2017-02-1018:10:27.263811RXVerifyExample[4940:2469821]2thread:0x174262e80
2017-02-1018:10:30.369209RXVerifyExample[4940:2469813]4thread:0x1742648c0
2017-02-1018:10:31.369205RXVerifyExample[4940:2469821]3thread:0x174262e80


并行异步3

//并行异步3
-(void)test_queue_concurrent_async3
{
NSLog(@"并行异步方法3");
dispatch_queue_tqueue=dispatch_queue_create("com.demo.0043",DISPATCH_QUEUE_CONCURRENT);
NSLog(@"mainthread:%p",[NSThreadmainThread]);
dispatch_async(queue,^{
[NSThreadsleepForTimeInterval:2.1];
NSLog(@"1thread:%p",[NSThreadcurrentThread]);
});
dispatch_async(queue,^{
[NSThreadsleepForTimeInterval:1.1];
NSLog(@"2thread:%p",[NSThreadcurrentThread]);
});
dispatch_async(queue,^{
[NSThreadsleepForTimeInterval:4.1];
NSLog(@"3thread:%p",[NSThreadcurrentThread]);
});
dispatch_async(queue,^{
[NSThreadsleepForTimeInterval:3.1];
NSLog(@"4thread:%p",[NSThreadcurrentThread]);
});
}
//结果
2017-02-1018:10:59.926988RXVerifyExample[4942:2470140]并行异步方法3
2017-02-1018:10:59.927184RXVerifyExample[4942:2470140]mainthread:0x17007f8c0
2017-02-1018:11:01.033209RXVerifyExample[4942:2470183]2thread:0x170462ac0
2017-02-1018:11:02.033478RXVerifyExample[4942:2470185]1thread:0x170462f40
2017-02-1018:11:03.037799RXVerifyExample[4942:2470176]4thread:0x170462a40
2017-02-1018:11:04.033691RXVerifyExample[4942:2470177]3thread:0x170462480


从并行异步的三个例子来看。

创建的新的线程的数目是不确定的，是跟队列中异步方法个数和异步方法执行的时间有关。
                                            

                                        

                        
                        内容来自用户分享和网络整理，不保证内容的准确性，如有侵权内容，可联系管理员处理 点击这里给我发消息 
                    

                    

                    

                        

                         标签： 
                                                

                        

                    


                

            


            

                
相关文章推荐

                

                

                    
                

            

        

        

            

            
            

                

                    
新的分享

                    

                        
                    

                

            


            

                

                    
章节导航