Is "Out of Memory" a recoverable error?

[Robert Jacques]

On Wed, 03 Dec 2008 08:34:43 -0500, Leandro Lucarella <llucax at gmail.com>  
wrote:

> Walter Bright, el  2 de diciembre a las 04:13 me escribiste:
>> I asked this over on stackoverflow.com to see what people using other  
>> languages
>> have to say, as well as the D community. The reason I ask is to see if  
>> memory
>> allocation can be allowed in functions marked "nothrow".
>>
>> http://stackoverflow.com/questions/333736/is-out-of-memory-a-recoverable-error
>
> I think all the things said in this thread makes sense (adding callbacks
> to the garbage collector, adding a way to ask for memory that don't throw
> if the memory can't be allocated), but I think this don't cover all the
> possible scenarios.
>
> For example, I'm working on a softswitch (unfortunately no in D). Lets  
> say
> we have a really bad moment and all the subscribers want to talk at the
> same time and we don't support that workload. Lets say our memory is
> exhausted and a new call arrive. A new allocation is done somewhere deep
> inside the call logic, so the PRE COLLECT callback is called. No memory
> can be reclaimed, so the GC runs a collection. Still no memory. POST
> COLLECT and CRISIS are called too without success. My softswitch is down,
> I lost all the current calls. This is not good for business. What I  
> really
> wanted to do is to catch the memory error as shallow in the call logic as
> possible and drop only that current call, leaving all the current
> established calls intact.
>
> So what can I do? Should I manually check each and every allocation in  
> all
> the call logic? I think that's unacceptable.
>
> I think this scenario apply to each client-server application that needs
> to stay alive even with high workloads, as the expense of dropping some
> connection/client (web servers or web applications for example, as  
> someone
> said in stackoverflow.com).
>

That's a good point/use case. However,
1) Many client-sever applications seperate each client into a logical  
thread of some kind. And inside this thread, out of memory is not  
recoverable.
2) One can still catch an error if need be.