GCD温故而知新1

GCD 三中queue
1.1 main queue
1.2 global queue
1.3 自己创建 queue
1.3.1 自己创建 queue 分两种
1>串行 dispatch_queue_t serial_queue = dispatch_queue_create("lcc", DISPATCH_QUEUE_SERIAL);
2>并行 dispatch_queue_t serial_concurrent = dispatch_queue_create("lccc", DISPATCH_QUEUE_CONCURRENT);

线程 有两种
2.1 sync 同步
2.2 async 异步

//异步 主队列
-(void)asyncMainQueue{
dispatch_queue_t main_queue = dispatch_get_main_queue();

for (int i = 0; i<5; i++) {
    dispatch_async(main_queue, ^{
        NSLog(@"i = %d",i);
        NSLog(@"current thread = %@",[NSThread currentThread]);
    });
}
for (int i = 0; i<5; i++) {
    NSLog(@"=%@",[NSThread currentThread]);
}
}
2016-11-07 13:39:55.601 gcd[5411:330259] ={number = 1, name = main}
2016-11-07 13:39:55.602 gcd[5411:330259] ={number = 1, name = main}
2016-11-07 13:39:55.603 gcd[5411:330259] ={number = 1, name = main}
2016-11-07 13:39:55.603 gcd[5411:330259] ={number = 1, name = main}
2016-11-07 13:39:55.604 gcd[5411:330259] ={number = 1, name = main}
2016-11-07 13:39:55.611 gcd[5411:330259] i = 0
2016-11-07 13:39:55.611 gcd[5411:330259] current thread = {number = 1, name = main}
2016-11-07 13:39:55.612 gcd[5411:330259] i = 1
2016-11-07 13:39:55.612 gcd[5411:330259] current thread = {number = 1, name = main}
2016-11-07 13:39:55.612 gcd[5411:330259] i = 2
2016-11-07 13:39:55.613 gcd[5411:330259] current thread = {number = 1, name = main}
2016-11-07 13:39:55.613 gcd[5411:330259] i = 3
2016-11-07 13:39:55.613 gcd[5411:330259] current thread = {number = 1, name = main}
2016-11-07 13:39:55.614 gcd[5411:330259] i = 4
2016-11-07 13:39:55.726 gcd[5411:330259] current thread = {number = 1, name = main}

异步主队列分析
异步是不阻塞我们的当前线程(主线程) 所以下面for循环的 NSLog(@"=%@",[NSThread currentThread]);先被打印.async和main_queue组合没有创建新的线程还是在当前线程中(主线程)这个时候当前线程(主线程)有下面的for循环打印任务所以要等下面的任务打印好上面的for循环才会打印

// 异步 全局队列
-(void)asyncGlobleQueue{
dispatch_queue_t globle_queue = dispatch_get_global_queue(0, 0);

for (int i = 0; i<5; i++) {
    dispatch_async(globle_queue, ^{
        NSLog(@"i = %d",i);
        NSLog(@"current thread = %@",[NSThread currentThread]);
    });
}
for (int i = 0; i<5; i++) {
    NSLog(@"+++%@",[NSThread currentThread]);
}
}
2016-11-07 13:52:18.783 gcd[5479:341111] i = 4
2016-11-07 13:52:18.783 gcd[5479:341056] +++{number = 1, name = main}
2016-11-07 13:52:18.783 gcd[5479:341092] i = 1
2016-11-07 13:52:18.783 gcd[5479:341094] i = 3
2016-11-07 13:52:18.783 gcd[5479:341091] i = 2
2016-11-07 13:52:18.783 gcd[5479:341109] i = 0
2016-11-07 13:52:18.783 gcd[5479:341056] +++{number = 1, name = main}
2016-11-07 13:52:18.783 gcd[5479:341111] current thread = {number = 3, name = (null)}
2016-11-07 13:52:18.784 gcd[5479:341094] current thread = {number = 5, name = (null)}
2016-11-07 13:52:18.784 gcd[5479:341092] current thread =  {number = 4, name = (null)}
2016-11-07 13:52:18.784 gcd[5479:341091] current thread = {number = 6, name = (null)}
2016-11-07 13:52:18.784 gcd[5479:341056] +++{number = 1, name = main}
2016-11-07 13:52:18.784 gcd[5479:341109] current thread = {number = 7, name = (null)}
2016-11-07 13:52:18.784 gcd[5479:341056] +++{number = 1, name = main}
2016-11-07 13:52:18.793 gcd[5479:341056] +++{number = 1, name = main}

异步全局队列分析
首先异步没有阻塞当前线程(主线程) 所以打印的第二行就已经打印了我们下面的for循环了根据打印的log可以清楚的看到 async和globle_queue创建了新的线程解释一下打印的顺序打印第一行
2016-11-07 13:52:18.783 gcd[5479:341111] i = 4 这个时候创建了新的线程(非主线程)是在新的线程中打印的,不阻塞当前线程(主线程)
2016-11-07 13:52:18.783 gcd[5479:341056] +++{number = 1, name = main}就是在当前线程打印的上面开辟了一个新线程做他自己的事下面当前线程做自己的事想象一下就是第一个for循环一下就走完了没循环一次(就可能)创建一个线程就结束循环了打印就是在这创建的各个线程中异步打印..所以上面 for循环的顺序和下面的就乱了

//异步 穿行队列
-(void)asyncSerialQueue{
dispatch_queue_t serial_queue = dispatch_queue_create("com.rea", DISPATCH_QUEUE_SERIAL);

for (int i = 0; i<10; i++) {
    dispatch_async(serial_queue, ^{
        NSLog(@"---i = %d",i);
        NSLog(@"current thread = %@",[NSThread currentThread]);
    });
}

for (int i = 0; i<5; i++) {
    NSLog(@"+++%@",[NSThread currentThread]);
}
}

2016-11-07 14:19:17.060 gcd[5549:360426] +++{number = 1, name = main}
2016-11-07 14:19:17.060 gcd[5549:360461] ---i = 0
2016-11-07 14:19:17.061 gcd[5549:360426] +++{number = 1, name = main}
2016-11-07 14:19:17.061 gcd[5549:360461] current thread = {number = 3, name = (null)}
2016-11-07 14:19:17.062 gcd[5549:360426] +++{number = 1, name = main}
2016-11-07 14:19:17.062 gcd[5549:360461] ---i = 1
2016-11-07 14:19:17.062 gcd[5549:360426] +++{number = 1, name = main}
2016-11-07 14:19:17.062 gcd[5549:360461] current thread = {number = 3, name = (null)}
2016-11-07 14:19:17.062 gcd[5549:360426] +++{number = 1, name = main}
2016-11-07 14:19:17.062 gcd[5549:360461] ---i = 2
2016-11-07 14:19:17.062 gcd[5549:360461] current thread = {number = 3, name = (null)}
2016-11-07 14:19:17.062 gcd[5549:360461] ---i = 3
2016-11-07 14:19:17.062 gcd[5549:360461] current thread = {number = 3, name = (null)}
2016-11-07 14:19:17.063 gcd[5549:360461] ---i = 4
2016-11-07 14:19:17.078 gcd[5549:360461] current thread = {number = 3, name = (null)}
2016-11-07 14:19:17.078 gcd[5549:360461] ---i = 5
2016-11-07 14:19:17.078 gcd[5549:360461] current thread = {number = 3, name = (null)}
2016-11-07 14:19:17.078 gcd[5549:360461] ---i = 6
2016-11-07 14:19:17.078 gcd[5549:360461] current thread = {number = 3, name = (null)}
2016-11-07 14:19:17.078 gcd[5549:360461] ---i = 7
2016-11-07 14:19:17.079 gcd[5549:360461] current thread = {number = 3, name = (null)}
2016-11-07 14:19:17.079 gcd[5549:360461] ---i = 8
2016-11-07 14:19:17.079 gcd[5549:360461] current thread = {number = 3, name = (null)}
2016-11-07 14:19:17.079 gcd[5549:360461] ---i = 9
2016-11-07 14:19:17.080 gcd[5549:360461] current thread = {number = 3, name = (null)}

异步穿行队列分析
异步不会阻塞当前线程所以第一行打印的是下面的for循环
2016-11-07 14:19:17.060 gcd[5549:360426] +++{number = 1, name = main}
async 和serial_queue组合会创建新的线程但是只会创建一个线程各个线程做各个的事情打印就是各打印各的. 异步穿行只会创建一个线程在这个所以这个异步串行是有顺序的额

// 异步 并行
-(void)asyncConcurrentQueue{
dispatch_queue_t concurrent_queue = dispatch_queue_create("lccc", DISPATCH_QUEUE_CONCURRENT);

for (int i = 0; i<10; i++) {
    dispatch_async(concurrent_queue, ^{
        NSLog(@"i = %d",i);
        NSLog(@"current thread = %@",[NSThread currentThread]);
    });
}
for (int i = 0; i<5; i++) {
    NSLog(@"+++%@",[NSThread currentThread]);
}}

2016-11-07 14:30:55.875 gcd[5596:370161] i = 2
2016-11-07 14:30:55.875 gcd[5596:370159] i = 1
2016-11-07 14:30:55.875 gcd[5596:370127] +++{number = 1, name = main}
2016-11-07 14:30:55.875 gcd[5596:370174] i = 0
2016-11-07 14:30:55.876 gcd[5596:370177] i = 5
2016-11-07 14:30:55.876 gcd[5596:370176] i = 4
2016-11-07 14:30:55.875 gcd[5596:370158] i = 3
2016-11-07 14:30:55.876 gcd[5596:370159] current thread = {number = 4, name = (null)}
2016-11-07 14:30:55.876 gcd[5596:370127] +++{number = 1, name = main}
2016-11-07 14:30:55.876 gcd[5596:370178] i = 6
2016-11-07 14:30:55.876 gcd[5596:370161] current thread = {number = 3, name = (null)}
2016-11-07 14:30:55.876 gcd[5596:370177] current thread = {number = 6, name = (null)}
2016-11-07 14:30:55.876 gcd[5596:370174] current thread = {number = 5, name = (null)}
2016-11-07 14:30:55.877 gcd[5596:370179] i = 7
2016-11-07 14:30:55.877 gcd[5596:370158] current thread = {number = 8, name = (null)}
2016-11-07 14:30:55.877 gcd[5596:370127] +++{number = 1, name = main}
2016-11-07 14:30:55.877 gcd[5596:370180] i = 8
2016-11-07 14:30:55.877 gcd[5596:370159] i = 9
2016-11-07 14:30:55.877 gcd[5596:370176] current thread = {number = 7, name = (null)}
2016-11-07 14:30:55.877 gcd[5596:370178] current thread = {number = 9, name = (null)}
2016-11-07 14:30:55.877 gcd[5596:370179] current thread = {number = 10, name = (null)}
2016-11-07 14:30:55.884 gcd[5596:370127] +++{number = 1, name = main}
2016-11-07 14:30:55.884 gcd[5596:370180] current thread = {number = 11, name = (null)}
2016-11-07 14:30:55.884 gcd[5596:370159] current thread = {number = 4, name = (null)}
2016-11-07 14:30:55.885 gcd[5596:370127] +++{number = 1, name = main}

异步并行队列分析
貌似和异步 globle队列是一样的....

====================================================================================================
异步的说完了现在说一下同步
1 同步 mainQueue
2同步 globleQueue
3同步 serialQueue
3同步 concurrentQueue
第一种我会在下一篇单独讨论下面三种简单说一下如图下图

EE9372F8-FA11-490B-A269-DB9481BE1BB6.png

同步的意思是 (不创建线程) 重点哦当前在神马线程那么block代码块里面就会在神马线程并且同步会立马回调重点哦立马回调
所以如图所示 for循环所在的线程是主线程那么block里面肯定也是主线程下面for 循环也是主线程记住同步会立马回调并且block里和下面的for循环都是zai 一个线程在任何(一个)线程中做任务那么都是有先后顺序的. 所以fou循环运行的如图 164 行就会立马回调打印block里面的知道fou循环结束再打印下面for循环的 ...

打印效果是这样的

A7F3A549-FAC5-403C-BBCE-45A5BEE83EF7.png

希望我说明白了

GCD温故而知新1

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