Hello everyone! I'm learning D and trying to write some sample code in D.
I wrote: http://codepad.org/K4xQOREZ
It compiles well with dmd 2.0.59, but I got an error when running:
    object.Error: Access Violation
Any one help? Thanks.

What's in console?

On Saturday, 5 May 2012 at 09:16:04 UTC, Kagamin wrote:
> What's in console?

object.Error: Access Violation
----------------
----------------

Expected output:
12341234123....

PS:
Line 13 should be: write(Idx);

On Saturday, 5 May 2012 at 09:28:34 UTC, Tongzhou Li wrote:
> On Saturday, 5 May 2012 at 09:16:04 UTC, Kagamin wrote:
>> What's in console?
>
> object.Error: Access Violation
> ----------------
> ----------------
>
> Expected output:
> 12341234123....
>
> PS:
> Line 13 should be: write(Idx);

By default, everything is TLS (thread local) ... so, cv[0] will be null in main even though another thread set it to something else.

Adding __gshared in front of "Condition[4] cv;" on line 7 will make it not crash with the Access Violation. However, I highly recommend you read the concurrency chapter in the DPL book: http://www.informit.com/articles/article.aspx?p=1609144

On Saturday, 5 May 2012 at 08:45:21 UTC, Tongzhou Li wrote:
> I wrote: http://codepad.org/K4xQOREZ

Besides the other things mentioned, you also need to lock the monitor associated with a condition before notifying/waiting (cf. a recent discussion on the druntime list).

David

On Saturday, 5 May 2012 at 17:03:00 UTC, Chris Cain wrote:
> On Saturday, 5 May 2012 at 09:28:34 UTC, Tongzhou Li wrote:
>> On Saturday, 5 May 2012 at 09:16:04 UTC, Kagamin wrote:
>>> What's in console?
>>
>> object.Error: Access Violation
>> ----------------
>> ----------------
>>
>> Expected output:
>> 12341234123....
>>
>> PS:
>> Line 13 should be: write(Idx);
>
> By default, everything is TLS (thread local) ... so, cv[0] will be null in main even though another thread set it to something else.
>
> Adding __gshared in front of "Condition[4] cv;" on line 7 will make it not crash with the Access Violation. However, I highly recommend you read the concurrency chapter in the DPL book: http://www.informit.com/articles/article.aspx?p=1609144

Thanks. Now it works fine with gdc, but still prints nothing with dmd. It seems that "cv[0].notify()" on line 29 affects nothing at all when using dmd2 :(

On Saturday, 5 May 2012 at 18:46:32 UTC, David Nadlinger wrote:
> On Saturday, 5 May 2012 at 08:45:21 UTC, Tongzhou Li wrote:
>> I wrote: http://codepad.org/K4xQOREZ
>
> Besides the other things mentioned, you also need to lock the monitor associated with a condition before notifying/waiting (cf. a recent discussion on the druntime list).
>
> David

Why? There's no data races...

On Sunday, 6 May 2012 at 04:54:44 UTC, Tongzhou Li wrote:
> Why? There's no data races...

It's part of the protocol/contract/whatever you want to call it of condition variables as implemented in druntime.

David

On Sunday, 6 May 2012 at 04:52:48 UTC, Tongzhou Li wrote:
> Thanks. Now it works fine with gdc, but still prints nothing with dmd. It seems that "cv[0].notify()" on line 29 affects nothing at all when using dmd2 :(

I'm not exactly sure what's going on for it not to work for you, but here's the code I have (I used stdout.flush() because in some command prompts it won't display until it reaches a new line '\n' character otherwise). Maybe this will work better.

https://gist.github.com/5a9b7f611f33ee143880

On Sunday, 6 May 2012 at 10:39:04 UTC, Chris Cain wrote:
> On Sunday, 6 May 2012 at 04:52:48 UTC, Tongzhou Li wrote:
>> Thanks. Now it works fine with gdc, but still prints nothing with dmd. It seems that "cv[0].notify()" on line 29 affects nothing at all when using dmd2 :(
>
> I'm not exactly sure what's going on for it not to work for you, but here's the code I have (I used stdout.flush() because in some command prompts it won't display until it reaches a new line '\n' character otherwise). Maybe this will work better.
>
> https://gist.github.com/5a9b7f611f33ee143880

I used stdout.flush() then it works. Thanks.