How to parallelize the build of multiple configurations in the same source code directory

[HalfSweet]

I have a requirement where I want to build multiple configurations simultaneously in the same source code directory, similar to the difference between Debug and Release. I tried running two scons commands directly to build, but occasionally encountered errors like the following

FileNotFoundError: [Errno 2] No such file or directory: '.sconsign.tmp' -> '.sconsign.dblite':
  File "/home/gitlab-runner/.sifli/python_env/sifli-sdk2.3_py3.10_env/lib/python3.10/site-packages/SCons/Script/Main.py", line 1515:
    _exec_main(parser, values)
  File "/home/gitlab-runner/.sifli/python_env/sifli-sdk2.3_py3.10_env/lib/python3.10/site-packages/SCons/Script/Main.py", line 1469:
    _main(parser)
  File "/home/gitlab-runner/.sifli/python_env/sifli-sdk2.3_py3.10_env/lib/python3.10/site-packages/SCons/Script/Main.py", line 1214:
    nodes = _build_targets(fs, options, targets, target_top)
  File "/home/gitlab-runner/.sifli/python_env/sifli-sdk2.3_py3.10_env/lib/python3.10/site-packages/SCons/Script/Main.py", line 1403:
    jobs.run(postfunc = jobs_postfunc)
  File "/home/gitlab-runner/.sifli/python_env/sifli-sdk2.3_py3.10_env/lib/python3.10/site-packages/SCons/Taskmaster/Job.py", line 114:
    postfunc()
  File "/home/gitlab-runner/.sifli/python_env/sifli-sdk2.3_py3.10_env/lib/python3.10/site-packages/SCons/Script/Main.py", line 1400:
    SCons.SConsign.write()
  File "/home/gitlab-runner/.sifli/python_env/sifli-sdk2.3_py3.10_env/lib/python3.10/site-packages/SCons/SConsign.py", line 131:
    syncmethod()
  File "/home/gitlab-runner/.sifli/python_env/sifli-sdk2.3_py3.10_env/lib/python3.10/site-packages/SCons/dblite.py", line 199:
    self._os_replace(self._tmp_name, self._file_name)

For CI services, such occasional errors are critical, and without reviewing the detailed logs, it is impossible to determine whether the issue stems from code problems or what appears to be a data race problem. I would like to know if there are any best practices in SCons for parallel builds of multiple configurations?

[mwichmann]

By simultaneous builds, you mean concurrent running of SCons instances from the same source tree? That doesn't work, mainly for the reason in the snip above: the signature database is a single file, with no resource protection beyond the one you see (writing to a temporary and renaming it). You'll always be fighting over the contents of that file. You might be able to improve on things by arranging for each build flavor to have its own sconsign:

https://scons.org/doc/production/HTML/scons-man.html#f-SConsignFile

It's possible that judicious use of environments and variant directories can let you do such a build with a single SCons invocation.

[bdbaddog]

@HalfSweet You can build multiple variants via one invocation of scons by using VariantDirs()'s (easier if you specify them in your call to SConsign()..
(This is exactly the use model VariantDirs are meant for)