Re: [Boost-users] boost.regex with ICU memory cleanup on windows

Subject: Re: [Boost-users] boost.regex with ICU memory cleanup on windows
From: Alex Perry (Alex.Perry_at_[hidden])
Date: 2011-08-02 23:22:04

John Maddock wrote on Tue, 2 Aug 2011 12:14:53 +0100
> There are a number of issues here:
> 
> 1) Your call to u_cleanup() occurs while a u32regex object is still in existence,
> so any ICU data being cached is actually still being used at that point.

I couldn't get u_cleanup() to work anywhere - ie 

BOOST_AUTO_TEST_CASE( u32_regex ) 
{
   {
        boost::u32regex re( boost::make_u32regex("\\d{3}"));
   }
    u_cleanup();
}
Or having u_cleanup() in a fixture teardown (which is how it was in the original code) doesn't seem to make any difference

> 2) Boost.Regex does cache some internal data for improved performance -
> this is relatively small and gets cleared after main() exits.
> 3) Point (2) means that a call to _CrtDumpMemoryLeaks() before main exits
> will report leaks, where as using something like:
> 
> struct cleanup
> {
>    ~cleanup()
>    {
>       _CrtDumpMemoryLeaks();
>    }
> };
> 
> cleanup c;

The boost unit test framework does appear to do the memory dump in a destructor of a static object - I guess whether the regex library statics are destructed first depends on the order of loading - not sure if there is any easy way of ensuring that the unit test framework is destructed last (perhaps if I link to UTF as a static library?).

> 4) Other leak detectors such as valgrind and VLD report no errors (and give
> much more useful reports than the brain-dead MS ones IMO).
> 
> HTH, John.

:-) yes I agree - my current solution is --detect_memory_leaks=0 when running the unit tests - which at least stops the report.  

I was hoping that this was a reasonably common issue and there was some clean up function (like u_cleanup()) specifically for the regex library but if not can live with switching off memory loss detection.  

Thanks a lot for the help here though - it is much appreciated.

Alex