Re: [RFC]serialize the output of parallel make?

[Howard Chu]

Chiheng Xu wrote:
> On Fri, Jul 30, 2010 at 6:01 PM, Howard Chu<address@hidden>  wrote:
> > Chiheng Xu wrote:
> > > On Fri, Jul 30, 2010 at 5:35 PM, Eli Zaretskii<address@hidden>    wrote:
> > > > I asked for an example.  Could you please show a "messy" output and
> > > > the output you'd like to have after "serialization"?
> > > >
> > > > TIA
> > >
> > > serially make : execute  A, B, C programs, they print:
> > >
> > > A:  Hello, I'm A, I am from Earth.
> > > B:  The moon is my home.
> > > C:  Welcome to Mars, It's an amazing planet.
> > >
> > > parallely make : the output of A, B, C programs interleave :
> > >
> > > C:  Welcome to
> > > B:  The moon is my
> > > A:  Hello, I'm A, I am from Earth.home.Mars, It's an amazing planet.
> >
> > This seems like quite an extreme example. stdout is line buffered by
> > default, so individual lines would get written atomically unless the
> > programs you're running are doing weird things with their output. In the
> > common case interleaving like this doesn't happen within lines, it only
> > happens between lines of multi-line output. stderr may skew things since
> > it's usually nonbuffered, but again, that's not the common case.
>
> I use "make -j 4" to build and test gcc, the situation above is very common.

Then it means you're getting a lot of diagnostics written to stderr, and you 
should probably look into why you're getting so many. I routinely do large 
builds with "make -j24" on a 16 core server and the output doesn't have 
problems like that. If you're getting lots of diagnostics while building gcc, 
then you're probably going to wind up with a broken compiler when it's done.

Garbage-in-garbage-out. Prettying up the make output isn't going to solve that.
--
  -- Howard Chu
  CTO, Symas Corp.           http://www.symas.com
  Director, Highland Sun     http://highlandsun.com/hyc/
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