只要是主队列就不会开线程

作者: test158888 | 来源:发表于2016-10-30 18:31 被阅读101次

只要是主队列就不会开线程
iOS线程安全问题
GCD
iOS GCD 常用功能
iOS多线程-并发队列
06 GCD 并发队列
iOS开发—GCD笔记
谈谈dispatch_sync 和 dispatch_async
队列（一）
iOS开发笔记-多线程的使用方法

同步函数+（并发队列or主队列）的两种情况

dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^{
        dispatch_sync(dispatch_get_main_queue(), ^{
            NSLog(@"11  %@",[NSThread currentThread]);
        });
    });
     
    dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^{
        dispatch_sync(dispatch_get_main_queue(), ^{
            NSLog(@"22  %@",[NSThread currentThread]);
        });
    });
     
    dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^{
        dispatch_sync(dispatch_get_main_queue(), ^{
            NSLog(@"33  %@",[NSThread currentThread]);
        });
    });
     
    dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^{
        dispatch_sync(dispatch_get_main_queue(), ^{
            NSLog(@"44  %@",[NSThread currentThread]);
        });
    });
     
    dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^{
        dispatch_sync(dispatch_get_main_queue(), ^{
            NSLog(@"55  %@",[NSThread currentThread]);
        });
    });

一个接一个执行

dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^{
    dispatch_sync(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^{
        NSLog(@"11  %@",[NSThread currentThread]);
    });
});
 
dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^{
    dispatch_sync(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^{
        NSLog(@"22  %@",[NSThread currentThread]);
    });
});
 
dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^{
    dispatch_sync(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^{
        NSLog(@"33  %@",[NSThread currentThread]);
    });
});
 
dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^{
    dispatch_sync(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^{
        NSLog(@"44  %@",[NSThread currentThread]);
    });
});
 
dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^{
    dispatch_sync(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^{
        NSLog(@"55  %@",[NSThread currentThread]);
    });
});

异步执行