thread count is increasing every time we unload flash from process space a thread is left over

In general, if you're building a desktop or mobile application on top of the Flash runtime, Adobe AIR is the supported path.  There is a history of legacy applications embedding Flash Player; however, that approach is fragile, and not something we test or officially support.  We *do* have a network of third-party system integrators (aka. porting partners) that specialize in customizing and supporting the Flash Player in unique environments, and I can refer you to our business development group to discuss options in that vein.

Because there is a body of legacy applications that did embed Flash Player into executables, we do tend to fix things when they're broken catastrophically, but it's not an approach that we recommend (especially for new content), nor is it something that we're going to optimize or prioritize bugs for.  This approach is fragile, and because Windows 10 is a fast-moving target, we regularly break these kinds of applications while accommodating new changes to the Windows platform.

Off the top of my head, this isn't an issue that I'm aware of.  It's also not an issue that I believe that we'd invest a lot of effort into fixing unless it also affected the plug-in, when it is running inside a browser that's listed on our system requirements page.

Either way, we'd need to debug it to figure out what's going on.  The best path forward would be to file a bug at http://bugbase.adobe.com/ with an executable example that we can debug.  We probably do want to understand why it's happening; however, there are no guarantees that this is something that we would ultimately choose to invest engineering resources into fixing.