From 16ce2074812ad28806144dc897d3947805c05d9b Mon Sep 17 00:00:00 2001 From: Todd Gamblin Date: Mon, 4 Jan 2021 01:28:16 -0800 Subject: [PATCH] bugfix: infinite loop when building a set from incomplete specs (#20649) This code in `SpecBuilder.build_specs()` introduced in #20203, can loop seemingly interminably for very large specs: ```python set([spec.root for spec in self._specs.values()]) ``` It's deceptive, because it seems like there must be an issue with `spec.root`, but that works fine. It's building the set afterwards that takes forever, at least on `r-rminer`. Currently if you try running `spack solve r-rminer`, it loops infinitely and spins up your fan. The issue (I think) is that the spec is not yet complete when this is run, and something is going wrong when constructing and comparing so many values produced by `_cmp_key()`. We can investigate the efficiency of `_cmp_key()` separately, but for now, the fix is: ```python roots = [spec.root for spec in self._specs.values()] roots = dict((id(r), r) for r in roots) ``` We know the specs in `self._specs` are distinct (they just came out of the solver), so we can just use their `id()` to unique them here. This gets rid of the infinite loop. --- lib/spack/spack/solver/asp.py | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-) diff --git a/lib/spack/spack/solver/asp.py b/lib/spack/spack/solver/asp.py index 858b577662..2091dd8976 100644 --- a/lib/spack/spack/solver/asp.py +++ b/lib/spack/spack/solver/asp.py @@ -1601,7 +1601,12 @@ def build_specs(self, function_tuples): # fix flags after all specs are constructed self.reorder_flags() - for root in set([spec.root for spec in self._specs.values()]): + # inject patches -- note that we' can't use set() to unique the + # roots here, because the specs aren't complete, and the hash + # function will loop forever. + roots = [spec.root for spec in self._specs.values()] + roots = dict((id(r), r) for r in roots) + for root in roots.values(): spack.spec.Spec.inject_patches_variant(root) # Add external paths to specs with just external modules