[Dlang-internal] multi threading in dmd

[Robert Schadek]

Compiling is IMHO is getting painfully slow with growing projects.
One thing I'm working on is up to 30+ seconds, for 20k lines of 
somewhat heavy code.
But lets not argue whether or not or not I'm doing it wrong, for 
the sake of
the arguments lets assume compiling is slow.

One thing I see is that dub passes many files at once to dmd.
And dmd runs one thread on that input.

I think there is some opportunity to start multiple threads to do 
at least some of
the work in parallel.

1. Has anybody done any work on doing work in dmd with threads?

2. Am I correct that in theory dmd should be able to lex all 
passed files in
parallel (given enough cpu cores).

3. Is it correct that currently one token is created at a time on 
request by the
parser.

4. This would currently require the classes Identifier and 
StringTable be made
thread safe.

5. AsyncRead in mars.d is dead code?

6. Is there any way to test all the different version statements 
and static if's
used for the same purpose?

7. Is there a change to parse all the initially given files in 
parallel?

8. Any other ideas on how to do threading in dmd?