Bug#1064786: jruby: mri-extra - flaky TestOpen3 pipe tests

[Vladimir Petko]

Source: jruby
Version: 9.4.5.0+ds-1
Severity: normal
X-Debbugs-Cc: vladimir.petko at canonical.com

Dear Maintainer,

The autopkgtests for jruby fail `mri-extra` with the following errors:

  1) Failure:
TestOpen3#test_pipeline_start
[/tmp/autopkgtest.Dz4xQk/autopkgtest_tmp/test/mri/test_open3.rb:303]:
Failed assertion, no message given.

  2) Failure:
TestOpen3#test_pipeline_w
[/tmp/autopkgtest.Dz4xQk/autopkgtest_tmp/test/mri/test_open3.rb:288]:
<true> expected but was
<false>.

  3) Failure:
TestOpen3#test_capture3_flip
[/tmp/autopkgtest.Dz4xQk/autopkgtest_tmp/test/mri/test_open3.rb:190]:

The minimal reproducer of those:
----
require 'open3'

RUBY = 'jruby'
Open3.pipeline_r([RUBY, '-e', 'print "1"'],
                     [RUBY, '-e', 'print STDIN.read + "2"']) {|o,ts|
      print(o.read)
    }
---

executing the above sample results in the following output:
# jruby test.rb
12# jruby test.rb
12# jruby test.rb
12# jruby test.rb
12# jruby test.rb
2# jruby test.rb
12# jruby test.rb
2# jruby test.rb
12# jruby test.rb
2# jruby test.rb
2# jruby test.rb
2# jruby test.rb
2# jruby test.rb
12# jruby test.rb
12# jruby test.rb
2Errno::EPIPE: Broken pipe - <STDOUT>
   write at org/jruby/RubyIO.java:1569
   write at org/jruby/RubyIO.java:1458
   write at org/jruby/RubyIO.java:2829
   print at org/jruby/RubyIO.java:1831
   print at org/jruby/RubyKernel.java:649
  <main> at -e:1

Note: the failure occurs both with Java 17 and Java 21


-- System Information:
Debian Release: trixie/sid
  APT prefers mantic-updates
  APT policy: (500, 'mantic-updates'), (500, 'mantic-security'), (500, 'mantic'), (100, 'mantic-backports')
Architecture: amd64 (x86_64)
Foreign Architectures: i386

Kernel: Linux 6.5.0-21-generic (SMP w/32 CPU threads; PREEMPT)
Kernel taint flags: TAINT_PROPRIETARY_MODULE, TAINT_OOT_MODULE
Locale: LANG=en_US.UTF-8, LC_CTYPE=en_US.UTF-8 (charmap=UTF-8), LANGUAGE=en
Shell: /bin/sh linked to /usr/bin/dash
Init: systemd (via /run/systemd/system)
LSM: AppArmor: enabled