Critical Section in multithreading

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In a reader/writer multithreaded program, when only two threads, main thread to update GUI and worker thread to generate data for updating, does a reader (main thread) need to lock a shared memory? or both reader (main thread) and writer (worker thread) need to lock?

Thanks,

Posted 9-May-11 8:12am

ktn0805

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Espen Harlinn · Answer 1 · 2011-05-09T10:32:00

Solution 3

>> In a reader procedure, I have a while loop
>> checking if data[i] is available, if not sleep for a certain time,
>> otherwise go ahead and display the data. Is there any better way to do the checking?

Use Control.Invoke[^] to notify the UI thread. The method passed to Invoke will be executed on the UI thread.

You can even pass the new data as a parameter, enabling you to drop the locking entirely ...

Regards
Espen Harlinn

Posted 9-May-11 10:32am

Espen Harlinn

Comments

Sergey Alexandrovich Kryukov 9-May-11 20:43pm

Good locking is no locking, good point. My 5.
--SA

Espen Harlinn 10-May-11 2:53am

Thank you, SAKryukov!

Sergey Alexandrovich Kryukov 9-May-11 20:49pm

I added my some details and explanation in my answer, please see.
--SA

Sergey Alexandrovich Kryukov · Answer 2 · 2011-05-09T14:48:00

In addition to what Espen suggested: it can be either method Invoke or BeginInvoke of System.Threading.Dispatcher (can work with both WPF and Forms) or System.Windows.Forms.Control (Forms only, does not matter what instance of control; it just has to participate in currently running System.Windows.Forms.Application).

For detailed explanation on how it works and usage samples, please see my past answers:
Control.Invoke() vs. Control.BeginInvoke()[^],
Problem with Treeview Scanner And MD5[^].

—SA

OriginalGriff · Answer 3 · 2011-05-09T08:25:00

Solution 1

Both threads.
The idea of a lock is that when you try to acquire the lock, either you will get it or be suspended waiting for it. If only one thread locks the data, it does nothing useful to anything!

Posted 9-May-11 8:25am

OriginalGriff

ktn0805 · Answer 4 · 2011-05-09T08:54:00

Solution 2

In a reader procedure, I have a while loop checking if data[i] is available, if not sleep for a certain time, otherwise go ahead and display the data. Is there any better way to do the checking?

Posted 9-May-11 8:54am

ktn0805