[Scons-users] Scons always rebuilding

[Jeremy Elson]

Are you also migrating from a non-scons build system to scons? Or is it
that scons drove distcc properly but now is spuriously rebuilding when
you're using NFS files?

In your example compiler invocation, you elided the build flags. Are they
identical every time you run scons? scons rebuilds if the command line has
changed at all, e.g. if you're including a build timestamp in the complier
flags, or if the ordering of flags is not stable because you're storing
them in a set.

On Tue, Oct 27, 2020, 4:36 AM Stijn De Ruyck <Stijn.DeRuyck at onsemi.com>
wrote:

> Hello,
>
>
>
> We are in the process of migrating our development environment from
> individual workstations to a compute grid. In other words from local files
> & DistCC to NFS shares & LSF.
>
> We notice Scons 4.0.1 on Python 3.6.5/3.8.0 using the MD5 or MD5-timestamp
> decider is always rebuilding all targets. Scons thinks all dependencies
> have always changed even for what should be a no-op build.
>
>
>
> Source, target & external dependencies are on a single NFS share. Jobs are
> being submitted by wrapping g++ in LSF’s bsub command in the Scons CXX
> environment variable, similar to what we did with DistCC, which worked
> fine, but with DistCC everything was stored on local disks…
>
>
>
> Example --debug=explain when rerunning on a previous successful build:
>
>
>
> scons: rebuilding `build/debug/base/Date.o'
> because:
>
>            `base/Date.cc' is no longer a
> dependency
>
>            `base/Date.cc' is a new
> dependency
>
>
>            `base/Date.icc'
> changed
>
>
>            `base/BaseTypes.h'
> changed
>
>
>  (…)
>
>            `base/String.icc'
> changed
>
>
>            `base/String.tcc'
> changed
>
>
>            `/site/custom/tools/lsf/prod/prod/linux2.6-glibc2.3-x86_64/bin/bsub'
> changed
>
> bsub -I -n1 g++ -o build/debug/base/Date.o -c [...]
> -I/devel/tme/deps/include -I. base/Date.cc
>
>
>
> Any advice? :/
>
>
>
> Regards,
>
>
>
> Stijn
>
>
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