[Opensim-dev] .NET / Mono lock(obj) statement

[J Ross Nicoll]

I'd agree; it's nice Java stops you shooting yourself in the foot like  
this, but from a design point of view I prefer to make sure I lock  
only once. My own code tends towards having method names that end with  
"WithLock" for the version to be called after locking, to  
differentiate easily...

On 14 Jan 2009, at 14:11, Mike Dickson wrote:

> Even though it works in Java, IMO that's an example of poor design  
> vis.
> the locking protocol used.  Again, I agree the spec may say that the
> locking primitives should test for the thread doing the locking to  
> avoid
> a deadlock.  Even that won't avoid a deadlock involving a cycles  
> across
> multiple objects.
>
> Mike
>
> On Wed, 2009-01-14 at 04:57 +0000, Diva Canto wrote:
>> Hi everyone,
>>
>> Just got back from vacation to TP grief caused by extra locking
>> introduced in 7982. The extra locking is all good, but it seems that
>> certain things confuse the heck out of mono, so I thought I'd bring  
>> up
>> the issue here -- I'm pretty sure this problem occurs in other  
>> places of
>> the code too, so it's good to know what to expect. I'd certainly  
>> like to
>> find out more about the .NET spec.
>>
>> Here's a simplified version of the problem:
>>
>> lock (a)
>> {
>>   foo();
>> }
>>
>> void foo()
>> {
>>  lock (a)
>>  {
>>    ...
>>  }
>> }
>>
>> (the real situation is a bit more complicated; foo() involves a
>> delegate; but ignore that)
>>
>> In Java, this situation does NOT result in locking, because it's the
>> same thread that's acquiring object a. I can't find the spec for .NET
>> for this particular issue, but I'd be very surprised if it is  
>> different
>> from Java. Nevertheless, mono was deadlocking here; Windows was  
>> not. I
>> find the mono behavior very strange.
>>
>> Crista
>>
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> -- 
> Mike Dickson <mike.dickson at hp.com>
> ESS SW Platform Enablement
>
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