thread.patch

gistfile1.txt

diff --git a/src/org/jruby/RubyThread.java b/src/org/jruby/RubyThread.java
index f1f85b2..c45afe2 100644
--- a/src/org/jruby/RubyThread.java
+++ b/src/org/jruby/RubyThread.java
@@ -172,7 +172,11 @@ public class RubyThread extends RubyObject implements ExecutionContext {
     public ThreadContext getContext() {
         return contextRef.get();
     }
-    
+
+
+    public Thread getNativeThread() {
+        return threadImpl instanceof NativeThread ? ((NativeThread) threadImpl).getThread() : null;
+    }
     /**
      * Dispose of the current thread by removing it from its parent ThreadGroup.
      */
@@ -863,7 +867,7 @@ public class RubyThread extends RubyObject implements ExecutionContext {
 
     @JRubyMethod(compat = CompatVersion.RUBY1_9)
     public IRubyObject backtrace(ThreadContext context) {
-        return context.createCallerBacktrace(context.getRuntime(), 0);
+        return getContext().createCallerBacktrace(context.getRuntime(), 0);
     }
 
     public StackTraceElement[] javaBacktrace() {
diff --git a/src/org/jruby/runtime/ThreadContext.java b/src/org/jruby/runtime/ThreadContext.java
index e3e9c3e..c257117 100644
--- a/src/org/jruby/runtime/ThreadContext.java
+++ b/src/org/jruby/runtime/ThreadContext.java
@@ -795,12 +795,18 @@ public final class ThreadContext {
     }
     
     public RubyStackTraceElement[] gatherCallerBacktrace(int level) {
+        Thread nativeThread = thread.getNativeThread();
+
+        // Future thread or otherwise unforthgiving thread impl.
+        if (nativeThread == null) return new RubyStackTraceElement[] {};
+
         Backtrace[] copy = new Backtrace[backtraceIndex + 1];
+
         System.arraycopy(backtrace, 0, copy, 0, backtraceIndex + 1);
         RubyStackTraceElement[] trace = gatherHybridBacktrace(
                 runtime,
                 copy,
-                Thread.currentThread().getStackTrace(),
+                nativeThread.getStackTrace(),
                 false);
 
         return trace;