GCD 同步异步的串行和并发问题

来源：互联网发布：淘宝客佣金编辑：程序博客网时间：2024/06/05 01:54

    //1.主对列:(串行队列)

    dispatch_queue_t mainQueue=dispatch_get_main_queue();

    NSLog(@"%@",[NSThread currentThread]);




    //2.全局并行队列

    dispatch_queue_t concu=dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT,0);





    //3.创建串行队列

    dispatch_queue_t queueSerial=dispatch_queue_create("jrqueue1",DISPATCH_QUEUE_SERIAL);





    //4.创建并行队列

    dispatch_queue_t queueConcu=dispatch_queue_create("jrqueue2",DISPATCH_QUEUE_CONCURRENT);

//同步执行+串行队列

//主队列:卡死(死锁)

//自定义:顺序执行走主线程

    /*

     dispatch_sync(queueSerial, ^{

     [NSThread sleepForTimeInterval:2];

     NSLog(@"同步串行队列1-----%@",[NSThread currentThread]);

     });



     dispatch_sync(queueSerial, ^{

     [NSThread sleepForTimeInterval:2];

     NSLog(@"同步串行队列2-----%@",[NSThread currentThread]);

     });


    */


    //同步执行+并行队列走主线程

//主队列:顺序执行

//自定义:顺序执行

    /*
     dispatch_sync(queueConcu, ^{

     [NSThread sleepForTimeInterval:2];

     NSLog(@"同步并行队列1-----%@",[NSThread currentThread]);

     });



     dispatch_sync(queueConcu, ^{

     [NSThread sleepForTimeInterval:2];

     NSLog(@"同步并行队列2-----%@",[NSThread currentThread]);

     });


    */


    //异步执行+串行队列-----开启一个子线程，且顺序执行
//主队列:顺序执行(走主线程)
//自定义:顺序执行:(开辟子线程,子队列共用一个线程)

     dispatch_async(queueSerial, ^{

     [NSThread sleepForTimeInterval:2];

     NSLog(@"异步串行队列1-----%@",[NSThread currentThread]);

     });



     dispatch_async(queueSerial, ^{

     [NSThread sleepForTimeInterval:2];

     NSLog(@"异步串行队列2-----%@",[NSThread currentThread]);

     });



     dispatch_async(queueSerial, ^{

     [NSThread sleepForTimeInterval:2];

     NSLog(@"异步串行队列3-----%@",[NSThread currentThread]);

     });





    //异步执行+并行队列----开启多个线程，且并发执行(无序)

//主队列: 无序执行(开辟子线程,每一个任务单独开辟一个线程)

//自定义:无序执行(开辟子线程,每一个任务单独开辟一个线程)

//相同:当主线程走到子线程是,子线程会同时执行

     dispatch_async(concu, ^{

     [NSThread sleepForTimeInterval:2];

     NSLog(@"异步并行队列1-----%@",[NSThread currentThread]);

     });



     dispatch_async(concu, ^{

     [NSThread sleepForTimeInterval:2];

     NSLog(@"异步并行队列2-----%@",[NSThread currentThread]);

     });



     dispatch_async(concu, ^{

     [NSThread sleepForTimeInterval:2];

     NSLog(@"异步并行队列3-----%@",[NSThread currentThread]);

     });


    */


    //主对列+同步执行-----死锁（将以下两个添加到主队列，等待前面的执行完成（loadView。loadData之类的），但是当执行到这一步时，形成死循环）


     /*
     dispatch_sync(mainQueue, ^{

     [NSThread sleepForTimeInterval:2];

     NSLog(@"同步主队列1-----%@",[NSThread currentThread]);

     });



     dispatch_sync(mainQueue, ^{

     [NSThread sleepForTimeInterval:2];

     NSLog(@"同步主队列2-----%@",[NSThread currentThread]);

     });

    */

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