Fix potential hang when joining threads.

If the thread termination invokes user code after `th->status` becomes
`THREAD_KILLED`, and the user unblock function causes that `th->status` to
become something else (e.g. `THREAD_RUNNING`), threads waiting in
`thread_join_sleep` will hang forever. We move the unblock function call
to before the thread status is updated, and allow threads to join as soon
as `th->value` becomes defined.

This reverts commit 6505c77501f1924571b2fe620c5c7b31ede0cd22.

1 files changed, 39 insertions, 0 deletions

diff --git a/test/fiber/test_thread.rb b/test/fiber/test_thread.rb
index 843604b5f1..5c25c43de2 100644
--- a/test/fiber/test_thread.rb
+++ b/test/fiber/test_thread.rb
@@ -20,6 +20,31 @@ class TestFiberThread < Test::Unit::TestCase
     assert_equal :done, thread.value
   end
 
+  def test_thread_join_implicit
+    sleeping = false
+    finished = false
+
+    thread = Thread.new do
+      scheduler = Scheduler.new
+      Fiber.set_scheduler scheduler
+
+      Fiber.schedule do
+        sleeping = true
+        sleep(0.1)
+        finished = true
+      end
+
+      :done
+    end
+
+    Thread.pass until sleeping
+
+    thread.join
+
+    assert_equal :done, thread.value
+    assert finished, "Scheduler thread's task should be finished!"
+  end
+
   def test_thread_join_blocking
     thread = Thread.new do
       scheduler = Scheduler.new
@@ -66,4 +91,18 @@ class TestFiberThread < Test::Unit::TestCase
       thread.join
     end
   end
+
+  def test_thread_join_hang
+    thread = Thread.new do
+      scheduler = SleepingUnblockScheduler.new
+
+      Fiber.set_scheduler scheduler
+
+      Fiber.schedule do
+        Thread.new{sleep(0.01)}.value
+      end
+    end
+
+    thread.join
+  end
 end