1.用户自定义线程队列,创建时很容易创建 注意创建时的第一个参数:标记值,方便调试查看
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dispatch_queue_t serialqueue=dispatch_queue_create( "serialqueue" , DISPATCH_QUEUE_SERIAL); //串行线程队列
dispatch_queue_t concurrentqueue=dispatch_queue_create( "concurrent" , DISPATCH_QUEUE_CONCURRENT); //并行线程队列
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2.创建之后那如何验证它是串行还是并行的呢?
第一种:
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dispatch_apply(5, concurrentqueue, ^(size_t index) { NSLog (@ "%ld" ,index);
});
dispatch_apply(5, serialqueue, ^(size_t index) {
NSLog (@ "%ld" ,index);
});
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输出结果:
第一个循环输出无序第一个有序,可以看出第一个是多线程并行,第二哥是单线程串行。
第二种:
(1)串行的验证:
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dispatch_async(serialqueue, ^{ NSLog (@ "1" );
});
dispatch_async(serialqueue, ^{
NSLog (@ "2" );
});
dispatch_async(serialqueue, ^{
NSLog (@ "3" );
});
dispatch_async(serialqueue, ^{
NSLog (@ "4" );
});
dispatch_async(serialqueue, ^{
NSLog (@ "5" );
});
dispatch_async(serialqueue, ^{
NSLog (@ "6" );
});
dispatch_async(serialqueue, ^{
NSLog (@ "7" );
});
dispatch_async(serialqueue, ^{
NSLog (@ "8" );
});
dispatch_async(serialqueue, ^{
NSLog (@ "9" );
});
dispatch_async(serialqueue, ^{
NSLog (@ "10" );
});
dispatch_async(serialqueue, ^{
NSLog (@ "11" );
});
dispatch_async(serialqueue, ^{
NSLog (@ "12" );
});
dispatch_async(serialqueue, ^{
NSLog (@ "13" );
});
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输出结果:
可以看到输出结果连续。
(2)并行的验证:
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dispatch_async(concurrentqueue, ^{ NSLog (@ "1" );
});
dispatch_async(concurrentqueue, ^{
NSLog (@ "2" );
});
dispatch_async(concurrentqueue, ^{
NSLog (@ "3" );
});
dispatch_async(concurrentqueue, ^{
NSLog (@ "4" );
});
dispatch_async(concurrentqueue, ^{
NSLog (@ "5" );
});
dispatch_async(concurrentqueue, ^{
NSLog (@ "6" );
});
dispatch_async(concurrentqueue, ^{
NSLog (@ "7" );
});
dispatch_async(concurrentqueue, ^{
NSLog (@ "8" );
});
dispatch_async(concurrentqueue, ^{
NSLog (@ "9" );
});
dispatch_async(concurrentqueue, ^{
NSLog (@ "10" );
});
dispatch_async(concurrentqueue, ^{
NSLog (@ "11" );
});
dispatch_async(concurrentqueue, ^{
NSLog (@ "12" );
});
dispatch_async(concurrentqueue, ^{
NSLog (@ "13" );
});
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输出结果:
由此可见:输出结果不连续。
3.从上面的两个输出结果可以看出:串行是在一个线程上执行任务,而并行是在多个线程上执行任务。