US Patent 7865914 Cooperative DLL unload

Loading and unloading a plurality of libraries on a computing device having a loader lock and internal and external counts for each library in the plurality of libraries is disclosed. The libraries assume an initialize state, followed by an initialized state, a pending unload state, and an unload state according to when the internal and external counts are incremented and decremented. When in the pending unload state, the functions of a library that include functions that require acquiring the loader lock exit, the internal count is decremented by one, and the loader lock is released. Prior to entering the pending unload state, a library may be placed into a reloadable state. A library in the reloadable state may be reloaded upon request until a timer times out. When the timer times out, the library in the reloadable state transitions into the pending unload state.