[fpc-devel] OO rewrite - technical questions

[Michael Schnell]

  On 07/24/2010 04:55 AM, Hans-Peter Diettrich wrote:
>> Moreover the point with threadvars is that threads that use the same 
>> code see different values in the same threadvar. These threads of 
>> course can't use different registers to access them as the run the 
>> same code.
>
> Consider a threadvar as a field of a related thread object (instance).
>
It is very clear what a threadvar is: the same variable automatically is 
instantiated dedicated for each thread while  a normal (static or 
global) variable is instantiated once for all threads. Multiple threads 
that each use different code don't need threadvars as they can be 
programmed to use individual static/global variables. Inly if the same 
code is used for multiple threads, threadvars are necessary to allow 
these threads to identify themselves (e.g a threadvar can store an ID 
number for the thread so that it can know who it is without doing an OS 
API call.

-Michael