* ext/thread/thread.c (rb_szqueue_clear): notify SZQUEUE_WAITERS

  on SizedQueue#clear. [ruby-core:59462] [Bug #9342]

* test/thread/test_queue.rb: add test. the patch is from
  Justin Collins.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@44595 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

1 files changed, 22 insertions, 0 deletions

diff --git a/test/thread/test_queue.rb b/test/thread/test_queue.rb
index 438e1e75e3..bf8344fade 100644
--- a/test/thread/test_queue.rb
+++ b/test/thread/test_queue.rb
@@ -122,6 +122,28 @@ class TestQueue < Test::Unit::TestCase
     assert_same q, retval
   end
 
+  def test_sized_queue_clear
+    # Fill queue, then test that SizedQueue#clear wakes up all waiting threads
+    sq = SizedQueue.new(2)
+    2.times { sq << 1 }
+
+    t1 = Thread.new do
+      sq << 1
+    end
+
+    t2 = Thread.new do
+      sq << 1
+    end
+
+    t3 = Thread.new do
+      Thread.pass
+      sq.clear
+    end
+
+    [t3, t2, t1].each(&:join)
+    assert_equal sq.length, 2
+  end
+
   def test_sized_queue_push_return_value
     q = SizedQueue.new(1)
     retval = q.push(1)