blocks|key|3126855|text|“低级线程”的典型实现是pthreads。通常与pthread一起教授的线程问题的最基本示例是某种形式的readers+and+writers+problem。该页面还链接到更经典的线程问题，如生产者/消费者和进餐哲学家。|type|unstyled|depth|inlineStyleRanges|entityRanges|offset|length|data|3126856|entityMap|0|LINK|mutability|MUTABLE|url|http://en.wikipedia.org/wiki/POSIX_Threads|1|http://en.wikipedia.org/wiki/Readers-writers_problem^0|C|8|0|1G|R|1|0^^$0|@$1|2|3|4|5|6|7|N|8|@]|9|@$A|O|B|P|1|Q]|$A|R|B|S|1|T]]|C|$]]|$1|D|3|-4|5|6|7|U|8|@]|9|@]|C|$]]]|E|$F|$5|G|H|I|C|$J|K]]|L|$5|G|H|I|C|$J|M]]]]

The canonical implementation of "low level threads" is <a href="http://en.wikipedia.org/wiki/POSIX_Threads" rel="nofollow noreferrer">pthreads</a>. The most basic examples of threading problems that are usually taught along with pthreads are some form of <a href="http://en.wikipedia.org/wiki/Readers-writers_problem" rel="nofollow noreferrer">readers and writers problem</a>. That page also links to more classical threading problems like producers/consumers and dining philosophers.

blocks|key|5383165|text|他可能指的是你对C#的使用，而不是你的线程经验。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|5383166|entityMap^0|0^^$0|@$1|2|3|4|5|6|7|D|8|@]|9|@]|A|$]]|$1|B|3|-4|5|6|7|E|8|@]|9|@]|A|$]]]|C|$]]

He was probably referring to your use of C#, not your threading experience.

blocks|key|3127355|text|如果是一家游戏公司，他们可能想要这样的答案：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|3127356|“我实现了一个多线程的AI例程，在可用的CPU资源中为NPCs分配决策树计算。正确的锁定很困难，特别是在将代码与应用程序的其余部分集成时。我们还花了一些时间跟踪每个线程的资源使用情况，以便在AI处理威胁到干扰主UI响应时控制它。”|3127357|(这一切都是我编造的，我个人并没有做过任何事情。(笑)|3127358|entityMap^0|0|0|0^^$0|@$1|2|3|4|5|6|7|H|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|I|8|@]|9|@]|A|$]]|$1|D|3|E|5|6|7|J|8|@]|9|@]|A|$]]|$1|F|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|G|$]]

If it is a game company, then they probably want an answer something like this:

"I implemented a multithreaded AI routine that allocated decision-tree calculations for NPCs among the available CPU resources. Correct locking, especially when integrating the code with the rest of the app, was difficult. We also spent some time tracking per-thread resource usage so we could throttle back the AI processing when it threatened to interfere with main UI responsiveness."

(I made all that up, I personally have not actually done any of that. grin)

blocks|key|3127030|text|这里有一个使用pthread的快速示例，基于我们的一些测试代码。它产生两个线程，并等待它们完成。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|3127031|int+main(+void+)
{
++pthread_t+reader,+writer;
++void+*arg;

++//+[...+initialisation+...]

++//+Spawn+threads
++if(+pthread_create(+&reader,+NULL,+reader_func,+arg+)+%7C%7C
++++++pthread_create(+&writer,+NULL,+writer_func,+arg+)+)
++++{
++++++perror(+"pthread_create"+);
++++++return+EX_OSERR;
++++}

++//+Wait+while+threads+run
++pthread_join(+reader,+&arg+);
++pthread_join(+writer,+&arg+);

++return+EX_OK;
}

void+*reader_func(+void+*arg+)
{
++//+[...+do+some+stuff+...]
++return+NULL;
}

void+*writer_func(+void+*arg+)
{
++//+[...+do+some+different+stuff+...]
++return+NULL;
}|code-block|syntax|javascript|3127032|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

Here's a quick example of using pthreads, based on some test code of ours. It spawns two threads, and waits for them to complete.
<pre><code>int main( void )
{
 pthread_t reader, writer;
 void *arg;

 // [... initialisation ...]

 // Spawn threads
 if( pthread_create( &amp;reader, NULL, reader_func, arg ) ||
 pthread_create( &amp;writer, NULL, writer_func, arg ) )
 {
 perror( &quot;pthread_create&quot; );
 return EX_OSERR;
 }

 // Wait while threads run
 pthread_join( reader, &amp;arg );
 pthread_join( writer, &amp;arg );

 return EX_OK;
}

void *reader_func( void *arg )
{
 // [... do some stuff ...]
 return NULL;
}

void *writer_func( void *arg )
{
 // [... do some different stuff ...]
 return NULL;
}
</code></pre>

blocks|key|3971925|text|我会看看http://zthread.sourceforge.net/，它是PThreads库的一个很好的包装器。它是一个非常快速和稳定的库，可以是相当低级的库。写得很好，文档也很清楚。|type|unstyled|depth|inlineStyleRanges|entityRanges|offset|length|data|3971926|entityMap|0|LINK|mutability|MUTABLE|url|http://zthread.sourceforge.net/^0|4|V|0|0^^$0|@$1|2|3|4|5|6|7|L|8|@]|9|@$A|M|B|N|1|O]]|C|$]]|$1|D|3|-4|5|6|7|P|8|@]|9|@]|C|$]]]|E|$F|$5|G|H|I|C|$J|K]]]]

I'd take a look at <a href="http://zthread.sourceforge.net/" rel="nofollow noreferrer">http://zthread.sourceforge.net/</a> which is an excellent wrapper around PThreads library. It's a very fast and stable and can be rather low-level library.
Very well written and documented.

blocks|key|3971983|text|老实说，我不认为你所做的和使用pthread之间有太大的区别。如果你在线程上做了大量的工作，你就会遇到所有的锁、同步等问题，并且可以很容易地直接使用pthread调用。有一件事你可能已经被隔离了，那就是终止，从线程中取出退出代码等等。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|3971984|(当然，pthread并不是您能获得的最低级别；如果您使用的是linux，请查看clone()以了解它在系统调用级别上的真正工作方式。但没有人真正使用它，除非他们实现了pthread。)|3971985|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|F|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|G|8|@]|9|@]|A|$]]|$1|D|3|-4|5|6|7|H|8|@]|9|@]|A|$]]]|E|$]]

I don't think there's much difference between what you've been doing and using pthreads, to be honest. If you've done a significant amount of work with threads you'll have had all the issues with locking, synchronisation etc, and could pick up using pthreads calls directly easily enough. The one thing that's slightly tricky that you've probably been insulated from is termination, getting exit codes out of the threads etc.

(Of course, pthreads isn't as low level as you can get; if you're on linux, look at clone() to see how it really works on a system call level. But no-one actually uses that unless they're implementing pthreads.)

blocks|key|816209|text|好吧，如果你真的想把这个想法发挥到“最大”，并且你愿意用线程弄脏你的手。我建议尝试实现一个用户空间线程库。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|816210|研究uconext.h及其各种过程(setcontext、swapcontext和makecontext)，并尝试用它们编写一个简单的协作线程库。实现锁、条件变量线程创建/销毁和协作让步。它不会特别花哨(即没有真正的并行性(因为你需要深入研究克隆系统调用或内核)，但如果你能做到这一点，没有人会说你没有低级经验。|816211|只是为了让你对这个项目的规模有个大概的了解。我在大约500行的c%2B%2B代码中编写了这样一个简单的线程库，考虑到其中至少有20%25是注释、断言语句和用于调试的日志记录。|816212|entityMap^0|0|0|0^^$0|@$1|2|3|4|5|6|7|H|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|I|8|@]|9|@]|A|$]]|$1|D|3|E|5|6|7|J|8|@]|9|@]|A|$]]|$1|F|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|G|$]]

well if you really want to take this idea to the "max" and you are willing to get your hands dirty with threads. I would recommend trying to implement a user space thread library. 

look into uconext.h and its various procedures (setcontext, swapcontext and makecontext) and try to write a simple cooperative thread library with them. implement locks, condition variables thread creation/destruction and cooperative yielding. It won't be particularly fancy (i.e. there is no actualy parallelism (for that you need to ether dig into the clone system call or the kernel) but if you can do it no one will be able to say you don't have low level experience.

Just to give a sense of the scale of the project. I wrote just such a simple thread library in about 500 lines of c++, and considering that at least 20% of that was comments, assert statements and logging for debugging purposes.

blocks|key|3972312|text|此外，Boost+Threads是一个相当便携的pthreads和Windows线程的包装器……据我所知，许多游戏开发商店都在使用C%2B%2B和一些Boost库。|type|unstyled|depth|inlineStyleRanges|entityRanges|offset|length|data|3972313|entityMap|0|LINK|mutability|MUTABLE|url|http://www.boost.org/doc/libs/1_36_0/doc/html/thread.html^0|3|D|0|0^^$0|@$1|2|3|4|5|6|7|L|8|@]|9|@$A|M|B|N|1|O]]|C|$]]|$1|D|3|-4|5|6|7|P|8|@]|9|@]|C|$]]]|E|$F|$5|G|H|I|C|$J|K]]]]

Also <a href="http://www.boost.org/doc/libs/1_36_0/doc/html/thread.html" rel="nofollow noreferrer">Boost Threads</a> is fairly portable wrapper around pthreads and Windows threads... and from what I hear many game dev shops use C++ and like some of the Boost libraries.

I'm a kinda newbie developer with a few years under my belt. Recently I interviewed at a game company and was asked "have you done any multi-threading?" I told them about having a C# app with a few Threads... and then I said a bit about transactions and locking etc in Sql. The interviewer politely told me that this was too high-level and they are looking for someone with experience doing multi-threading in C++.

So what is a basic example of "low-level" multi-threading in C++ ?

What is a basic example of "low-level" multi-threading in C++?

翻译质量差，导致语言生硬或混乱。

没有提供实际的解决方法或示例。

解答不清晰，无法理解或解决问题。

页面排版不美观，阅读体验差。

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我是一个有几年经验的新手开发者。最近我在一家游戏公司面试，被问到“你做过多线程吗？”我告诉他们有一个带有几个线程的C#应用程序...然后我谈到了Sql中的事务和锁定等问题。面试官礼貌地告诉我，这太高级了，他们正在寻找有在C++中做多线程经验的人。那么，C++中“低级”多线程的基本示例是什么呢？

问C++中“低级”多线程的基本示例是什么？
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回答 8

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