Re: threading in rpg. was RPG and Web.. (was Using OO conceptsinRPG)

[Hans Boldt <boldt@xxxxxxxxxx>]

Steve Richter wrote:
> I just figured I would ask Hans the technical reasons for threads not being
> supported in RPG.  Threads are not as mysterious as people might think they
> and they help programmers solve problems.

As discussed, there are two possible implementations: First, take 
all the global data and pass it in to each thread, which is pretty 
ugly to implement. Second, we could put mutexes around all accesses 
to global data, which is also pretty nasty. The latter may in fact 
be counter-productive in that any performance gain that might be 
achieved in a threaded solution may be eaten up by the additional 
overhead of all the mutexes.

Sure, threads are commonly used in TCP server applications, in that 
one thread is spun off for each request (not for each transaction). 
If you implement a Java Servlet or a HTTP server using Python's 
xxxHTTPServer classes (to pick a couple of HTTP frameworks), that's 
what happens - one thread per request. In such schemes, state 
persistence can be achieved by saving data in global data structures 
indexed by a transaction id.

I could go on, but I'm afraid the discussion would simply devolve 
into yet another comparison of RPG versus other languages better 
suited to HTTP processing.

Cheers! Hans