First big PITA in reallife D project

[Fawzi Mohamed]

On 19-ott-10, at 12:45, Stephan wrote:

> Hey guys I wanted to discuss my first major depressing experience  
> with D in a reallife project.
>
> First off here is the according bug report : http://d.puremagic.com/issues/show_bug.cgi?id=4951
>
> I have to mention that it was by far not the first bug i encountered  
> in D but it has never been such a PITA. I spent hours and hours of  
> searching, rewriting and crawling my code for the cause of this  
> issue. Just to finally find out that it was not my code but some bug  
> in druntime.
>
> What i do:
> I spawn multiple threads all periodically connecting to some  
> webservers waiting for the request to finish. Every request is  
> totally independent of the others. There is no data sharing in my  
> code. Now i have a protocol that makes my process send one last  
> important request when shutting down. For a clean shut down i wanted  
> to make sure that all the other threads are shut down first. That  
> way the final request of the process is the very last. So i wait for  
> every thread to finish their request and stop them.
> BUT it wont work like that. AFTER i stopped all other threads some  
> strange behavior of druntime makes every creation of an  
> InternetAddress instance (internally trying to resolve host)  
> impossible (throws an exception). Additionally even if the Internet  
> Addresses were created upfront the TcpSockets wont connect but throw.
> I have no idea what the heck is going on inside of the druntime that  
> could cause this but in my opinion it makes designing a big server  
> environment pretty much impossible because it would mean that i  
> cannot let any of my user generated threads exit unless i want to  
> shutdown completely anyway.
>
> Perhaps one side note: I am testing and having these issues under  
> Windows.
>
>
> I have never been so tempted to use another language while coding in  
> D as i was this time and that makes me sad.

I am not sure what is wrong in your case, and I worked only with D1/ 
tango on mac and linux, but I can definitely say that I had quite some  
very ugly bugs with threads and fibers, and gc.
I think I have fixed all of them (at least everything seems stable now).
Sean&co are welcome to take my fixes from tango into druntime, I  
release them with whatever license is needed: should I switch to D2 I  
will not complain if I don't have to debug those horrible things  
again... ;)

A non druntime bug you should maybe check if you use IP6 is the  
storage space you alloc for the address structure is large enough:  
sockaddr is too small, one should use sockaddr_storage (druntime is  
not always the culprit...).

good luck
Fawzi