[Scons-users] Internal Error: No dependency cycle found

[Stefan Ross]

Hi all,

I'm hoping you can help with what looks like a bug, but could be an
artifact of how I've designed my SConscript files.

I'm seeing the following error when doing parallel builds (-j4):

scons: done building targets.
Traceback (most recent call last):
  File "/usr/local/lib/scons-2.4.0/SCons/Script/Main.py", line 1371, in main
    _exec_main(parser, values)
  File "/usr/local/lib/scons-2.4.0/SCons/Script/Main.py", line 1334, in
_exec_main
    _main(parser)
  File "/usr/local/lib/scons-2.4.0/SCons/Script/Main.py", line 1099, in
_main
    nodes = _build_targets(fs, options, targets, target_top)
  File "/usr/local/lib/scons-2.4.0/SCons/Script/Main.py", line 1296, in
_build_targets
    jobs.run(postfunc = jobs_postfunc)
  File "/usr/local/lib/scons-2.4.0/SCons/Job.py", line 111, in run
    self.job.start()
  File "/usr/local/lib/scons-2.4.0/SCons/Job.py", line 429, in start
    self.taskmaster.cleanup()
  File "/usr/local/lib/scons-2.4.0/SCons/Taskmaster.py", line 1043, in
cleanup
    raise SCons.Errors.UserError(desc)
UserError: Found dependency cycle(s):
  Internal Error: no cycle found for node <deleted>
 (<SCons.Node.FS.File object at 0x40d4360>) in state pending
  Internal Error: no cycle found for node <deleted>
 (<SCons.Node.FS.File object at 0x40ca1d0>) in state pending
  Internal Error: no cycle found for node <deleted>
 (<SCons.Node.FS.Dir object at 0x34a7e60>) in state pending


scons: *** Found dependency cycle(s):
  Internal Error: no cycle found for node ...

I see a range of similar symptoms:

1)  When the error is as above, if I build again, there are still some more
targets which get built, i.e. the build has finished before all targets
have been built.
2)  Sometimes I get failures because a source file is not found when
building a target.  I've confirmed using --tree that the dependency has
been detected by scons.

Clues:

1) In case 2 above, the target is being built using a Pseudo-builder
(AddMethod)
2) We've been using this build system for a long time without these issues.
The main thing I've changed recently is using a lot more variant_dir
builds.  The targets I have most problems with were originally built in
SConstruct.  They are now built in a SConscript file in the same directory
as the SConstruct, using a variant_dir.

Any suggestions for how I can proceed to debug?

Thanks

Stefan
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