Do not null processor at the end of the while loop. Instead do it at the

front if there are (for some reason which in theory shouldn't happen) no
IRPs to process.

Author: kayahr

src/main/java/org/usb4java/javax/AbstractIrpQueue.java

@@ -83,33 +83,43 @@ final void process()
     {
         // Get the next IRP
         T irp = this.irps.poll();
-        while (irp != null)
+        
+        // If there are no IRPs to process then mark the thread as closing
+        // right away. Otherwise process the IRP (and more IRPs from the queue
+        // if present).
+        if (irp == null)
         {
-            // Process the IRP
-            try
-            {
-                processIrp(irp);
-            }
-            catch (final UsbException e)
+            this.processor = null;
+        }
+        else
+        {
+            while (irp != null)
             {
-                irp.setUsbException(e);
+                // Process the IRP
+                try
+                {
+                    processIrp(irp);
+                }
+                catch (final UsbException e)
+                {
+                    irp.setUsbException(e);
+                }
+    
+                // Get next IRP and mark the thread as closing before sending the
+                // events for the previous IRP
+                final T nextIrp = this.irps.poll();
+                if (nextIrp == null) this.processor = null;
+    
+                // Finish the previous IRP
+                irp.complete();
+                finishIrp(irp);
+    
+                // Process next IRP (if present)
+                irp = nextIrp;
             }
-
-            // Get next IRP and mark the thread as closing before sending the
-            // events for the previous IRP
-            final T nextIrp = this.irps.poll();
-            if (nextIrp == null) this.processor = null;
-
-            // Finish the previous IRP
-            irp.complete();
-            finishIrp(irp);
-
-            // Process next IRP (if present)
-            irp = nextIrp;
         }
 
         // No more IRPs are present in the queue so terminate the thread.
-        this.processor = null;
         synchronized (this.irps)
         {
             this.irps.notifyAll();