diff --git a/src/main/java/org/ids_mannheim/Worker.java b/src/main/java/org/ids_mannheim/Worker.java
index 1578a98..e1d052b 100644
--- a/src/main/java/org/ids_mannheim/Worker.java
+++ b/src/main/java/org/ids_mannheim/Worker.java
@@ -49,8 +49,8 @@
                 String fname = fnames.get(index);
                 File current_file = new File(fname);
                 long file_size = current_file.length();
-                int poolIndex = index % pool.size;
-                logger.info(String.format("%5d/%5d %-10s %-10s", index, fnames.size(), pool.getHost(poolIndex), current_file.getName()));
+                int poolIndex = pool.getNextFree();
+                logger.info(String.format("Started %d/%d %s %s", index, fnames.size(), pool.getHost(poolIndex), current_file.getName()));
                 String[] cmd = {
                         "/bin/sh",
                         "-c",
@@ -78,6 +78,7 @@
                     //noinspection ConstantConditions
                     slidingWindowQueue.add(strings[1]);
                 }
+                pool.markFree(poolIndex);
                 if (texts > 0) {
                     logger.info(pool.getHost(poolIndex)+" finished " + fname + " with "+texts+ " texts");
                     etaPrinter.update(file_size);
@@ -90,7 +91,6 @@
                     } else {
                         logger.severe ("Giving up " + fname);
                         index = queue.take();
-                        sleep(1000);
                     }
                 }
             }
diff --git a/src/main/java/org/ids_mannheim/WorkerNodePool.java b/src/main/java/org/ids_mannheim/WorkerNodePool.java
index 255809d..3d9485e 100644
--- a/src/main/java/org/ids_mannheim/WorkerNodePool.java
+++ b/src/main/java/org/ids_mannheim/WorkerNodePool.java
@@ -2,11 +2,16 @@
 
 import java.util.ArrayList;
 import java.util.Arrays;
+import java.util.Optional;
+import java.util.OptionalInt;
+import java.util.concurrent.CopyOnWriteArrayList;
 import java.util.stream.IntStream;
 
 public class WorkerNodePool {
-    ArrayList<String> execPool = new ArrayList<String>();
-    ArrayList<String> hostPool = new ArrayList<String>();
+    CopyOnWriteArrayList<String> execPool = new CopyOnWriteArrayList<>();
+    CopyOnWriteArrayList<String> hostPool = new CopyOnWriteArrayList<>();
+    CopyOnWriteArrayList<Boolean> busy = new CopyOnWriteArrayList<>();
+
     public final int size;
 
     public String getExec(int i) {
@@ -18,13 +23,31 @@
     }
 
     private String hostToExec(String host) {
-        if(host.equals("") || host.matches("local")) {
+        if (host.equals("") || host.matches("local")) {
             return "nice -5 ";
         } else {
             return " ssh " + host + " nice -5 ";
         }
     }
 
+    public void markFree(int i) {
+        busy.set(i, false);
+    }
+
+    public synchronized int getNextFree() throws InterruptedException {
+        while (true) {
+            OptionalInt result = IntStream.range(0, size).filter(i -> !busy.get(i)).findFirst();
+            if (result.isPresent()) {
+                int i = result.getAsInt();
+                busy.set(i, true);
+                return i;
+            } else {
+                TotalNGram.logger.warning("No free worker node. This should not happen.");
+                Thread.sleep(1000);
+            }
+        }
+    }
+
     public WorkerNodePool(String description) {
         Arrays.stream(description.split(", *")).forEachOrdered(s -> {
             String[] single = s.split("\\s*[*]\\s*");
@@ -44,6 +67,7 @@
             IntStream.range(0, procs).forEach(u -> {
                 hostPool.add(host);
                 execPool.add(hostToExec(host));
+                busy.add(false);
             });
 
         });