🚀 go-pugleaf

Keith R. Bennett (kbennett@access.digex.net) wrote:
: 
: 
: I have a question about thread programming.  Is there any way to make
: a given variable specific to an instance of a thread?
: 
: The best I can think of so far is to use either local variables, or
: variables allocated from the heap.  There is a large number of
: these variables that will be thread-specific, so I was thinking
: of putting them in structures and creating a new instance of each
: structure for each thread.
: 
: The C++ programmers guide mentions that there is a separate copy of
: errno for each thread.  Can I do that with my own variables?
: 

Yes, there is an errno for each thread. At least when you use
_begin_thread. I am not sure whether a new errno is created when you
directly call DosCreateThread.

With _begin_thread you can pass a parameter list to the thread. This
parameter list (it may contain simple variables as well as arrays and
structures) could be used to have thread-specifics.
This way you can preload some or all of these variables, which you
cannot when the thread allocated memory from the heap for its specifics.

WARNING: Do not use local variables (allocated on the stack) of the
procedure that calls _begin_thread as parameters to the thread. When
leaving the procedure, all your locals will be gone and the thread will
be 'ghost-operating' on your stack.

Han