Bug #13916: Race condition when sending a signal to a new fork

• Status: Closed
• Assignee: -
• Target version: -
• ruby -v: ruby 2.4.1p111 (2017-03-22 revision 58053) [x86_64-darwin16]
• Backport: 2.2: REQUIRED, 2.3: DONE, 2.4: DONE

[russelldavis (Russell Davis)]

To reproduce, run this script:

1_000_000.times do |i|
  pid = fork {sleep}
  puts pid
  Process.kill(:TERM, pid)
  Process.wait(pid)
end

Expected behavior: it should print a million pids and then exit.

Actual behavior: after some number of iterations, it freezes on the call to Process.wait, because the fork never got killed by the TERM signal. (I verified with ps that the pid it froze on is still running.)

[normalperson (Eric Wong)]

[e-mail] wrote:

https://bugs.ruby-lang.org/issues/13916

Oops, I don't think we block signals properly for plain fork' (vs spawn').
We need to use pthread_sigmask / sigprocmask to block signal.

I am testing this (slowly) and going to take a break while it
runs:

https://80x24.org/spew/[e-mail]/raw

• Status changed from Open to Closed

Applied in changeset trunk|r59975.

---

process: block/unblock signals around fork

As with forking for execve(2) in spawn', we must block signals to ensure they are handled correctly in a freshly fork'-ed child.

• process.c (retry_fork_ruby): block/unblock signals around fork
  (rb_fork_ruby): re-enable signals in forked child

• test/ruby/test_process.rb (test_forked_child_signal): new test
  [ruby-core:82883] [Bug #13916]

  Thanks to Russell Davis for the bug report and test case.

[normalperson (Eric Wong)]

Eric Wong [e-mail] wrote:

[e-mail] wrote:

https://bugs.ruby-lang.org/issues/13916
https://80x24.org/spew/[e-mail]/raw

Cleaned up and added test, committed as r59975

[normalperson (Eric Wong)]

• Status changed from Closed to Open
• Backport changed from 2.2: UNKNOWN, 2.3: UNKNOWN, 2.4: UNKNOWN to 2.2: REQUIRED, 2.3: REQUIRED, 2.4: REQUIRED

backport status change

[normalperson (Eric Wong)]

• Status changed from Open to Closed

closing to trigger backport of r59975

[nagachika (Tomoyuki Chikanaga)]

• Backport changed from 2.2: REQUIRED, 2.3: REQUIRED, 2.4: REQUIRED to 2.2: REQUIRED, 2.3: REQUIRED, 2.4: DONE

ruby_2_4 r62665 merged revision(s) 59975.

[usa (Usaku NAKAMURA)]

• Backport changed from 2.2: REQUIRED, 2.3: REQUIRED, 2.4: DONE to 2.2: REQUIRED, 2.3: DONE, 2.4: DONE

ruby_2_3 r62816 merged revision(s) 59975.