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Subject: Re: [boost] [pool] pool-based allocators and order of destruction
From: Stewart, Robert (Robert.Stewart_at_[hidden])
Date: 2011-05-23 12:59:04

John Maddock wrote:
> I'm looking for second opinions on this bug report:
> I see a number of solutions:
> * Document the limitation and leave it at that.
> * Make the singleton eternal and leak the pool's memory at
> program exit.
> * Use some kind of complex reference counting scheme so the
> pool is only
> destroyed when all it's memory has been released *and* main has
> exited.
> To be honest, I'm not thrilled by any of the above, but any
> opinions?

I leak Singletons to avoid late referencing problems. The OS cleans up the memory, of course, so the only problem is memory checking tools that complain about the leak. Those can be configured to ignore the Singleton, and the docs can describe the behavior and rationale, so I consider that a quick, safe, and practical solution to the problem.

If you want to avoid most memory leak complaints, you could create a second object that, upon destruction, asks the Singleton to release its dynamic resources. Then, if the Singleton is not actually used further, only the Singleton itself is leaked. OTOH, if there is a late use of the Singleton, it is still valid and can reacquire, and subsequently leak, whatever dynamic resources it then needs. (Then again, many memory checking tools look for leaks before statics are destroyed, in which case you are better off just letting the Singleton leak without extra steps.)

Rob Stewart robert.stewart_at_[hidden]
Software Engineer using std::disclaimer;
Dev Tools & Components
Susquehanna International Group, LLP

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