[jamming] Multiprocessing with Jam

John Waugh john.waugh at gmail.com
Sat Dec 6 12:11:53 PST 2008


I'm poking around with using JAMSHELL and -jN, but am having trouble.
It seems that the "slot number" is always 1, at least in my simple
case.

Here's an example Jamfile:

#------------------------------------------------------------

# rules, setup

rule Bla
{
	Depends all : $(<) ;
	Depends $(<) : $(>) ;
	doBla $(<) : $(>) ;
}

actions doBla
{
	@echo off
	echo process $(>) to $(<) (do something sloowww)
	echo results of processing $(>) > $(<)
}

JAMSHELL = cmd /C echo slot is: \! \& % ;

# the Jamfile contents

Bla foo : foo.txt ;
Bla bar : bar.txt ;

#------------------------------------------------------------

However, when I try "jam" or "jam all" or "jam foo bar", I get the two
actions run serially, both using slot 1.
Am I misunderstanding something?

I would have thought jam would give different slot numbers to two
actions that have nothing to do with each other.

I'm using FTJam 2.5.2, tried it on WinXP and FreeBSD (though the
example above is the WinXP version).

-John



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