diff --git a/htroot/Threaddump_p.java b/htroot/Threaddump_p.java
index ca9b36dc8..644713fd4 100644
--- a/htroot/Threaddump_p.java
+++ b/htroot/Threaddump_p.java
@@ -34,6 +34,7 @@ import java.util.ArrayList;
 
 import net.yacy.cora.protocol.RequestHeader;
 import net.yacy.kelondro.logging.ThreadDump;
+import net.yacy.kelondro.util.OS;
 
 import de.anomic.search.Switchboard;
 import de.anomic.server.serverObjects;
@@ -82,16 +83,16 @@ public class Threaddump_p {
             ThreadDump.appendStackTraceStats(appPath, buffer, traces, plain, null);
         } else {
             // write a thread dump to standard error output
-        	/*
-            if (OS.canExecUnix) {
-                int pid = OS.getPID();
-                if (pid >= 0) try {OS.execSynchronous("kill -3 " + pid);} catch (IOException e) {}
-            }
-            */
-            try {
-                new ThreadDump().appendBlockTraces(buffer, plain);
-            } catch (IOException e) {
-                e.printStackTrace();
+            File logFile = new File("yacy.log");
+            if (ThreadDump.canProduceLockedBy(logFile)) {
+                try {
+                    new ThreadDump(logFile).appendBlockTraces(buffer, plain);
+                } catch (IOException e) {
+                    e.printStackTrace();
+                }
+            } else if (OS.canExecUnix) {
+                ThreadDump.bufferappend(buffer, plain, "this thread dump function can find threads that lock others, to enable this function start YaCy with 'startYACY.sh -l'");
+                ThreadDump.bufferappend(buffer, plain, "");
             }
             
             // generate a single thread dump
diff --git a/source/net/yacy/kelondro/logging/ThreadDump.java b/source/net/yacy/kelondro/logging/ThreadDump.java
index 633b5e49e..3b7a3eaf9 100644
--- a/source/net/yacy/kelondro/logging/ThreadDump.java
+++ b/source/net/yacy/kelondro/logging/ThreadDump.java
@@ -28,7 +28,6 @@ package net.yacy.kelondro.logging;
 import java.io.BufferedReader;
 import java.io.ByteArrayInputStream;
 import java.io.File;
-import java.io.FileInputStream;
 import java.io.IOException;
 import java.io.InputStream;
 import java.io.InputStreamReader;
@@ -95,15 +94,26 @@ public class ThreadDump extends HashMap<ThreadDump.Thread, List<String>> impleme
         return java.lang.Thread.getAllStackTraces();
     }
     
-    public ThreadDump() throws IOException {
+    public static boolean canProduceLockedBy(File logFile) {
+
+        // check os version
+        if (!OS.canExecUnix) return false;
+        
+        // check if log file exists
+        if (!logFile.exists()) return false;
+        
+        // check last modification date of log file
+        if (System.currentTimeMillis() - logFile.lastModified() > 60000) return false;
+        
+        return true;
+    }
+    
+    public ThreadDump(File logFile) throws IOException {
         super();
         
         // try to get the thread dump from yacy.log which is available when YaCy is started with
         // startYACY.sh -l
-        if (!OS.canExecUnix) return;
-        
-        File logFile = new File("yacy.log");
-        if (!logFile.exists()) return;
+        if (!canProduceLockedBy(logFile)) return;
         long sizeBefore = logFile.length();
         
         // get the current process PID
@@ -126,10 +136,6 @@ public class ThreadDump extends HashMap<ThreadDump.Thread, List<String>> impleme
         importText(new ByteArrayInputStream(b));
     }
     
-    public ThreadDump(final File f) throws IOException {
-        this(new FileInputStream(f));
-    }
-    
     public ThreadDump(final InputStream is) throws IOException {
         super();
         importText(is);
@@ -248,14 +254,14 @@ public class ThreadDump extends HashMap<ThreadDump.Thread, List<String>> impleme
         bufferappend(buffer, plain, "");
         
         Map<Thread, Integer> locks = this.countLocks();
-        for (int i = 0; i < this.size() + 10; i++) {
+        for (int i = this.size() + 10; i > 0; i--) {
             for (Map.Entry<Thread, Integer> entry: locks.entrySet()) {
                 if (entry.getValue().intValue() == i) {
                 	bufferappend(buffer, plain, "holds lock for " + i + " threads:");
                 	final List<String> list = this.get(entry.getKey());
                     if (list == null) continue;
-                    bufferappend(buffer, plain, "Thread: " + entry.getKey());
-                    for (String s: list) bufferappend(buffer, plain, "  " + s);
+                    bufferappend(buffer, plain, "Thread= " + entry.getKey());
+                    for (String s: list) bufferappend(buffer, plain, "  " + (plain ? s : s.replaceAll("<", "&lt;").replaceAll(">", "&gt;")));
                     bufferappend(buffer, plain, "");
                 }
             }