Re: Parallel Make

[Noel Yap]

Tristan Van Berkom wrote:

> Noel Yap wrote:
>
> > I agree that a lone -j shouldn't default to infinity for practical 
> > reasons.  OTOH, a default of 1 would make the flag meaningless and a 
> > default of 2 seems unclean to me.  IMHO, -j shouldn't have a default 
> > at all.  Further, for those that like the infinite behaviour, I think 
> > allowing --jobs=infinity would help curb such an appetite a little.
>
>     Hmmm, the same could be said about the unix open system call; why
> should i have to open a named pipe in read/write if I dont want to block ?
> why not throw non-blocking behavior on as default and add a O_BLOCK flag
> instead ?
>
> Ok, so its a bad example; but what I'm getting at is that you cant just
> modify the expected behavior of the open() system call because everyone's
> code will instantly break, much in the same way as IMO, many build
> systems will break when you change the expected behavior of GNU make.
>
> If everyone is bent on changing that behavior, why not add something new
> like `-J' which behaves exactly like `-j' but with a different default
> behavior ?

To satisfy parsimony, I can understand why a default of infinity would be good. 
 OTOH, the issue here is that having an interface that makes a dangerous 
behaviour easy to invoke isn't good.

I would suspect that those using the default is in the minority.  They'll be 
the ones satisfying at least one of the below:
- not understanding the consequences of launching a large number of jobs.  
These developers will soon learn not to do this.
- working on small projects, but then, why use -j at all?
- using --max-load.  These developers can start using the proposed 
--jobs=infinity if they want to keep doing this.

For a small, stable group of developers, it's easy to say the developers should learn how to use the tool correctly.  When the number of developers grows, though, and these developers share a common set of compile servers, chances are, there's /always/ 
someone who needs to be educated so "educate them" will be much easier to follow if poor behaviour wasn't the default.

Noel