GThreadCount: TIdThreadSafeInteger = nil;

GThreadCount is a TIdThreadSafeInteger variable that represents the global count of TIdThread instances created for the application using the Indy library. 

Resources are allocated to the GThreadCount variable during initialization of the unit that contains the declaration (IdThread.pas). GThreadCount is freed when the unit is finalized. 

GThreadCount is updated when TIdThread instances are created or freed in the application. Creating a TTIdThread instance causes the value in GThreadCount to be incremented. Calling Destroy for the TIdThread instance causes the value in GThreadCount to be decremented. 

GThreadCount is used in TIdThread.WaitAllThreadsTerminated to determine when all executing or suspended TIdThread instances have been terminated.