等待线程 - 重访 [英] Waiting on a Thread - Revisited
问题描述
这是一个古老的问题，关于等待事情发生而不是
浪费时间做它。
采取两个线程：主线程和工作线程。工作线程是
读取串口，等待事情发生（服务
请求）。当它发生时它会引发一个事件。当然，在工作线程上执行事件
。这个想法是，当事件被引发时，处理程序
在串口发出命令并等待响应。问题是
，工作线程的一部分（用于回复）是
与它刚刚提出的事件捆绑在一起，因此无法监听
最新回复。
所以，我认为当事件发生时，我需要设置一个标志，
可以在主线程上获取。这样事件完成后，
工作线程回到侦听回复，主线程看到
标志并发出命令。
听起来不错，但现在我必须定期检查主要的
线程中的标志。这对我来说听起来非常糟糕，而且我不想浪费时间来投票。
我怎样才能抓住主线程何时发生变化，没有
坐下等待它？
像往常一样，关于如何做到这一点的任何建议总是受欢迎的，
但是很激进。
TIA
Charles
嗨Charles，
当我看到你的问题我的答案是直接遥控，但也许这可以
也由一个线程程序。这是一个老问题。在
我的意见需要一个堆栈。
那么为什么不使用arraylist创建一个堆栈。
每次从arraylist的第一行开始你的子步（
）（当踏板不活动时你可以使用线程轮询arraylist
）。 threading.sleep如果有什么东西）并删除
项目它已完成。
当你有东西时，你每次都添加到最后一行完成，
这个简单的解决方案在我看来会起作用
Cor
Charles Law< ; BL *** @ nowhere.com>写道：
< snip>
听起来不错，但现在我必须定期检查主要旗帜
线。这对我来说听起来非常糟糕，而且我不想浪费时间轮询。
如果主线程发生变化，我怎样才能抓住主线程中的标志
坐下来等待它？
像往常一样，任何关于如何做到这一点的建议总是受欢迎的，
无论如何激进。
我害怕我没有密切关注你的例子，但听起来像你基本上想要Monitor.Wait和Monitor.Pulse这样的b $ b。
我有一篇未完成的文章谈论它们（以及其他的b $ b b） - 它在
http://www.pobox.com/~skeet/csharp/multithreading.html
当我接触到它时，还有更多的东西，但是更多
监视方法中的位描述等待和脉冲。
（你也可以使用ManualResetEvent或AutoResetEvent。）
-
Jon Skeet - < sk *** @ pobox.com>
http：// www.pobox.com/~skeet
如果回复小组，请不要给我发邮件
Hi Cor
我刚刚阅读了Jon关于.NET中多线程的文章，现在我想知道等待和脉冲方法是如何工作的，所以我是试试这个。
看起来就像工作一样。
感谢您的建议，因为我认为它会帮助我/>
另一个区域，与同一任务相关。
查尔斯
" Cor Ligthert" <无********** @ planet.nl>在消息中写道
新闻：OZ **************** @ TK2MSFTNGP11.phx.gbl ...嗨Charles，
当我看到你的问题我的答案是直接遥控，但是也许这个
也可以通过线程程序来完成。这是一个老问题。我的意见中需要一个堆栈。
那么为什么不使用arraylist创建一个堆栈。
每次完成任务时你都会开始你的子步骤该arraylist的第一行
（当踏板未激活时，你可以使用thread.threading.sleep轮询arraylist
如果有的话）并删除它完成的项目。
当你完成
时，每次都会添加到最后一行，这个简单的解决方案在我看来会起作用
Cor
Hi guys. I''m back on the threading gig again.
It''s the age-old question about waiting for something to happen without
wasting time doing it.
Take two threads: the main thread and a worker thread. The worker thread is
reading the serial port, waiting for something to happen (a service
request). When it does it raises an event. Of course, the event is executed
on the worker thread. The idea is that when the event is raised, the handler
issues a command on the serial port and waits for a response. The problem is
that the part of the worker thread that does the listening (for replies) is
tied up with the event it has just raised, and therefore cannot listen for
the latest reply.
So, I think that when the event is raised, I need to set a flag perhaps,
that can be picked up on the main thread. This way the event completes, the
worker thread goes back to listening for replies, and the main thread sees
the flag and issues its command.
Sounds good, but now I have to periodically check for the flag in the main
thread. That sounds an awful lot like polling to me, and I don''t want to
waste time polling.
How can I catch the flag in the main thread when it changes, without having
to sit and wait for it?
As usual, any suggestions about how else to do this are always welcome,
however radical.
TIA
Charles
Hi Charles,
When I see your problem my answer is direct remoting, however maybe this can
also done by a threading program. It is a problem old as hell. There is in
my opinion needed a stack.
So why not create a stack using an arraylist.
You start your sub tread every time something is done from the first row of
that arraylist (when the tread is not active you can polling the arraylist
using the thread.threading.sleep if there is something) and delete that
item it is done.
While you add every time to the last row when there is something to be done,
this simple solution would work in my opinion
Cor
Charles Law <bl***@nowhere.com> wrote:
<snip>
Sounds good, but now I have to periodically check for the flag in the main
thread. That sounds an awful lot like polling to me, and I don''t want to
waste time polling.
How can I catch the flag in the main thread when it changes, without having
to sit and wait for it?
As usual, any suggestions about how else to do this are always welcome,
however radical.
I''m afraid I didn''t follow your example very closely, but it sounds
like you basically want Monitor.Wait and Monitor.Pulse.
I''ve got an unfinished article which talks about them (and other
things) - it''s at
http://www.pobox.com/~skeet/csharp/multithreading.html
There''s more to come when I get round to it, but the bit in "More
Monitor methods" described Wait and Pulse.
(You could also use ManualResetEvent or AutoResetEvent.)
--
Jon Skeet - <sk***@pobox.com>
http://www.pobox.com/~skeet
If replying to the group, please do not mail me too
Hi Cor
I have just read Jon''s article on multi-threading in .NET and I now
understand how the Wait and Pulse methods work, so I am going to try that.
It looks like just the job.
Thanks for your suggestion though, as I think it is going to help me in
another area, related to the same task.
Charles
"Cor Ligthert" <no**********@planet.nl> wrote in message
news:OZ****************@TK2MSFTNGP11.phx.gbl...Hi Charles,
When I see your problem my answer is direct remoting, however maybe this can also done by a threading program. It is a problem old as hell. There is in
my opinion needed a stack.
So why not create a stack using an arraylist.
You start your sub tread every time something is done from the first row of that arraylist (when the tread is not active you can polling the arraylist
using the thread.threading.sleep if there is something) and delete that
item it is done.
While you add every time to the last row when there is something to be done, this simple solution would work in my opinion
Cor
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