do an alive check before raising exception on fiber's thread

... otherwise leads to occassional NPE (seen on travis-ci) : ``` // [exec] 1) A Fiber that has been abandoned cleans itself up properly // [exec] Failure/Error: Unable to find org.jruby.ext.fiber.ThreadFiber.handleExceptionDuringExchange(ThreadFiber.java to read failed line // [exec] Java::JavaLang::NullPointerException: // [exec] # org.jruby.ext.fiber.ThreadFiber.handleExceptionDuringExchange(ThreadFiber.java:157) // [exec] # org.jruby.ext.fiber.ThreadFiber.exchangeWithFiber(ThreadFiber.java:115) // [exec] # org.jruby.ext.fiber.ThreadFiber.resume(ThreadFiber.java:90) ```
jruby · Dec 5, 2016 · 754fc04 · 754fc04
1 parent b17bee6
commit 754fc04
Showing 1 changed file with 2 additions and 2 deletions.
diff --git a/core/src/main/java/org/jruby/ext/fiber/ThreadFiber.java b/core/src/main/java/org/jruby/ext/fiber/ThreadFiber.java
@@ -154,7 +154,7 @@ private static void handleExceptionDuringExchange(ThreadContext context, FiberDa
         // Otherwise, we want to forward the exception to the target fiber
         // since it has the ball
         final ThreadFiber fiber = targetFiberData.fiber.get();
-        if ( fiber != null ) fiber.thread.raise(re.getException());
+        if ( fiber != null && fiber.alive() ) fiber.thread.raise(re.getException());
         else LOG.warn("no fiber thread to raise: {}", re.getException().inspect(context));
     }
 
@@ -239,7 +239,7 @@ public Map<Object, IRubyObject> getContextVariables() {
         return thread.getContextVariables();
     }
 
-    boolean alive() {
+    final boolean alive() {
         return thread != null && thread.isAlive() && !data.queue.isShutdown();
     }