From: nagachika00@...
Date: 2017-07-08T02:21:41+00:00
Subject: [ruby-core:81966] [Ruby trunk Bug#13632] Not processable interrupt queue for a thread after it's notified that FD is closed in some other thread.

Issue #13632 has been updated by nagachika (Tomoyuki Chikanaga).

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

ruby_2_4 r59286 merged revision(s) 58284,58812,59028.

----------------------------------------
Bug #13632: Not processable interrupt queue for a thread after it's notified that FD is closed in some other thread.
https://bugs.ruby-lang.org/issues/13632#change-65689

* Author: nvashchenko (Nikolay Vashchenko)
* Status: Closed
* Priority: Normal
* Assignee: 
* Target version: 
* ruby -v: 2.2.x, 2.3.x, 2.4.x, 2.5.x
* Backport: 2.2: UNKNOWN, 2.3: DONE, 2.4: DONE
----------------------------------------
In the bugfix for https://bugs.ruby-lang.org/issues/13076 has been introduced another bug, caused by a busy waiting in rb_notify_fd_close method, while the FD is being released. During this waiting, it pumps huge amounts of the ruby_error_stream_closed errors into thread's interrupt queue, which almost all stay there unprocessed. It can be up for several hundred of exceptions in the queue, depending on circumstances.

```
  a = []
  t = []
  10.times do
    r,w = IO.pipe
    a << [r,w]
    t << Thread.new do
      while r.gets
      end rescue IOError
      # Interrupt queue is full and all IO is broken
     Thread.current.pending_interrupt? # Expected to be false, because it's already rescued
      IO.sysopen ("/dev/tty")                   # Expected not to throw an error. On each such call, it dequeues the next item from interrupt queue until there's none
    end
  end
  a.each do |r,w|
    w.puts "test"
    w.close
    r.close
  end
  t.each do |th|
    th.join
  end
```

Output:

``` text
Traceback (most recent call last):
	1: from test2.rb:9:in `block (2 levels) in <main>'
test2.rb:9:in `sysopen': stream closed in another thread (IOError)
```
 







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