gmake && file time precision of 1 second

[Tristan Verniquet]

We have this problem too using recursive make and I am interested in 
what other solutions there are. Currently we sleep until the start of the next 
second using a custom binary, but it does slow down the 
build.

Another thing I've tried though haven't put much thought into is touching the lib file -1 second after each ar command.

Tristan

> Date: Mon, 13 Oct 2014 11:20:18 +0200
> From: guru at unixarea.de
> To: freebsd-hackers at freebsd.org
> Subject: gmake && file time precision of 1 second
> 
> 
> Hello,
> 
> I have a large project where a shell script fires up
> gmake runs in subdirs as:
> 
> for dir in src norm print ....; do 
>    cd $dir
>    gmake
>    cd ..
> done
> 
> in each subdir *.c are compiled to *.o and the resulting *.o are ar'ed
> into all the same lib.a; based on normal Makefile rules like:
> 
> SRCS = f1.c f2.c
> OBJS = $(SRCS:.c=.o)
> 
> .c.o:
> 	$(CC) -c ... $*.c
> 
> lib.a:: $(OBJS)
> 	$(AR) $@ $(OBJS)
> 
> 
> after moving to a faster server it turned out that gmake sometimes forget
> to ar the *.o into the lib; I investigated it and it turned out that the
> *.o files have the same modification time (in seconds) as the target
> lib.a (which was produced/updated in the last directory worked on) and
> gmake thinks that the lib.a is uptodate.
> 
> Any idea how to address this in the Makefiles?
> 
> Well I could place (and it works) a 'sleep 1' into the loop, but I think
> that there is some better way.
> 
> Thx
> 
> 	matthias
> -- 
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