handle ConcurrentModification Exception

gistfile1.diff

diff --git a/src/main/java/zmq/PollerBase.java b/src/main/java/zmq/PollerBase.java
index b1ad801..a37ed09 100644
--- a/src/main/java/zmq/PollerBase.java
+++ b/src/main/java/zmq/PollerBase.java
@@ -99,7 +99,7 @@ abstract public class PollerBase {
         //  Get the current time.
         long current = Clock.now_ms ();
 
-        ArrayList <Long> removes = new ArrayList <Long> ();
+        ArrayList <Long> executes = new ArrayList <Long> ();
         //   Execute the timers that are already due.
         long ret = 0L;
         for (Entry <Long, TimerInfo> o : timers.entrySet ()) {
@@ -112,14 +112,20 @@ abstract public class PollerBase {
                 ret = o.getKey() - current;
                 break;
             }
-
-            //  Trigger the timer.
-            o.getValue().sink.timer_event (o.getValue().id);
-            //  Remove it from the list of active timers.
-            removes.add (o.getKey ());
+            
+            // Add timer toexecution list
+            executes.add (o.getKey ());
         }
-        for (long key : removes)
+        for (long key : executes)
+        {
+          TimerInfo ti = timers.get(key);
+        	if(ti!=null)
+        	{
+                //  Trigger the timer.
+        		ti.sink.timer_event (ti.id);
+        	}
             timers.remove (key);
+        }
         //  There are no more timers.
         return ret;
     }

Thank you for addressing the issue.

Please send a pull request regarding this issue.

But please make sure the indentation is 4 spaces (no tabs).