Re: call/cc

[address@hidden (Kragen Sitaker)]

You write:
> Here's the single most practical reason why I love call/cc: Web
> application servers et filia.
> 
> - NThreads > CPUParallelism is a bad condition for high performance IO
>   systems.  Examples abound in which naively implemented fully 
>   asynchronous I/O engines beat the pants off of highly tuned 
>   multithreaded servers, up to the limit of 1 CPU.  

I don't quite understand the connection.  What are you counting as
"threads" in your NThreads?  Are you counting captured continuations
that will be resumed later, or not?  How about other user-level thread
packages that don't require a round trip into and out of the kernel for
each context switch?

While I've written some of the examples you mention myself, I don't
really know where the extra CPU time goes in multithreaded systems.

I think your (later) point about threads being harder to maintain is
debatable; writing complex asynchronous code (without call/cc, that is)
forces your program into explicit CPS, which is a major pain.