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From "Geir Magnusson Jr." <g...@pobox.com>
Subject Re: [drlvm] my latest round of patches broke something
Date Fri, 29 Sep 2006 19:35:14 GMT

On Sep 29, 2006, at 2:48 PM, Rana Dasgupta wrote:

> On 9/26/06, Alexey Varlamov <alexey.v.varlamov@gmail.com> wrote:
>>
>> >Just to be clear: I suggest we apply new_queued_cond_var.patch
>> >attached to HARMONY-1519 - provided that Artem will answer  
>> >comments.
>
>
> Hi,
>  I went through both the patches apr_cond.patch and
> new_queued_cond_var.patch on H-1519.
>  There is no perfect solution to implementing conditional waits on  
> Windows
> due to well documented reasons. The original apr implementation was  
> matching
> generations of releases to corresponding waits and the first patch  
> improves
> it, by getting the last waiter to reset the manual event( which seems
> logical ). As Artem commented on the JIRA, even this has known  
> issues...the
> loop is inefficient and there can be signal stealing and permanent  
> waits due
> lack of atomicity between apr_thread_mutex_unlock() and
> WaitForSingleObject().
>  Artem's patch new_queued_cond_var.patch looks simple and new, using
> synchronized wait queues. Just from reading, it seemed like a good  
> solution,
> there is no way ( at least for me )to understand that it is perfect  
> without
> a lot of testing.
>  These changes are  a maintenance hazard. Are we planning to stay
> compatible with APR? I don't know if APR is still an active  
> community. If
> so, we should not commit more changes, and ask on the APR list first.

Thanks for doing this.

My $0.02 - right now, this is a fix that helps make DRLVM more useful  
as we go forward, by fixing a problem in APR.  If we continue with  
APR, we either get this fix in there or maintain ourselves, *or* we  
throw APR overboard and do something else.

Either way, I don't see too much harm from a software process POV in  
applying.  Seems like we need it now.

Thoughts?

geir


>
> Thanks,
> Rana


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