#24424 closed defect (fixed)

Dancing links random failures

Reported by: vbraun Owned by:
Priority: major Milestone: sage-8.2
Component: combinatorics Keywords: random_fail
Cc: slabbe, vdelecroix Merged in:
Authors: Sébastien Labbé Reviewers: Volker Braun
Report Upstream: N/A Work issues:
Branch: 2df8c97 (Commits) Commit: 2df8c973e4b7f0c0ced1d45ecf3f2a273d971892
Dependencies: Stopgaps:

Description

The output of one_solution is random:

**********************************************************************
File "src/sage/combinat/matrices/dancing_links.pyx", line 27, in sage.combinat.matrices.dancing_links
Failed example:
    sorted(x.one_solution(ncpus=8))
Expected:
    [0, 1]
Got:
    [2, 3]
**********************************************************************
1 item had failures:
   1 of  20 in sage.combinat.matrices.dancing_links
    [175 tests, 1 failure, 8.38 s]
----------------------------------------------------------------------
sage -t --long src/sage/combinat/matrices/dancing_links.pyx  # 1 doctest failed
----------------------------------------------------------------------

Also, does ncpus=8 really use 8 cores? We already parallelize doctests! Tests should definitely not x8 that.

Change History (6)

comment:1 Changed 10 months ago by slabbe

  • Branch set to u/slabbe/24424
  • Commit set to 2df8c973e4b7f0c0ced1d45ecf3f2a273d971892

New commits:

2df8c9724424: fixing random doctests failures

comment:2 Changed 10 months ago by slabbe

  • Status changed from new to needs_review

comment:3 in reply to: ↑ description Changed 10 months ago by slabbe

Replying to vbraun:

Also, does ncpus=8 really use 8 cores? We already parallelize doctests! Tests should definitely not x8 that.

I changed 8 to 2. The dancing links problem in question uses only 6 rows. So, it is not something that will use a lot of cpu time (something like 1ms).

comment:4 Changed 10 months ago by vbraun

  • Reviewers set to Volker Braun
  • Status changed from needs_review to positive_review

comment:5 Changed 10 months ago by vbraun

  • Authors set to Sébastien Labbé

comment:6 Changed 10 months ago by vbraun

  • Branch changed from u/slabbe/24424 to 2df8c973e4b7f0c0ced1d45ecf3f2a273d971892
  • Resolution set to fixed
  • Status changed from positive_review to closed
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