Make sure a Monitor is not initialized twice

* Otherwise it makes it possible to have two threads enter the same Monitor concurrently, as they can acquire two different Mutex instances.
oracle · May 5, 2017 · 1adf384 · 1adf384
1 parent 7f73240
commit 1adf384
Showing 1 changed file with 1 addition and 0 deletions.
diff --git a/lib/mri/monitor.rb b/lib/mri/monitor.rb
@@ -239,6 +239,7 @@ def initialize(*args)
   # Initializes the MonitorMixin after being included in a class or when an
   # object has been extended with the MonitorMixin
   def mon_initialize
+    raise "already initialized" if @mon_mutex
     @mon_owner = nil
     @mon_count = 0
     @mon_mutex = Mutex.new