diff --git a/src/helma/xmlrpc/Benchmark.java b/src/helma/xmlrpc/Benchmark.java
index a39642ca..c64b3833 100644
--- a/src/helma/xmlrpc/Benchmark.java
+++ b/src/helma/xmlrpc/Benchmark.java
@@ -11,15 +11,15 @@ public class Benchmark implements Runnable {
 
     XmlRpcClient client;
     static String url;
-    static int clients = 8;
-    static int loops = 200;
+    static int clients = 16;
+    static int loops = 100;
 
     int gCalls = 0, gErrors = 0;
 
     Date date;
     
     public Benchmark () throws Exception {
-	client = new XmlRpcClient (url);
+	client = new XmlRpcClientLite (url);
 	
 	Vector args = new Vector ();
 	// Some JITs (Symantec, IBM) have problems with several Threads
diff --git a/src/helma/xmlrpc/XmlRpc.java b/src/helma/xmlrpc/XmlRpc.java
index d9ca8989..d1c72459 100644
--- a/src/helma/xmlrpc/XmlRpc.java
+++ b/src/helma/xmlrpc/XmlRpc.java
@@ -239,7 +239,7 @@ public abstract class XmlRpc extends HandlerBase {
     /**
      * Writes the XML representation of a supported Java object to the XML writer.
      */
-    void writeObject (Object what, XmlWriter writer)  {
+    void writeObject (Object what, XmlWriter writer) throws XmlRpcException {
 	writer.startElement ("value");
 	if (what == null) {
 	    // try sending experimental <ni/> element
@@ -295,7 +295,7 @@ public abstract class XmlRpc extends HandlerBase {
 	    }
 	    writer.endElement ("struct");
 	} else
-	    throw new RuntimeException ("unsupported Java type: " + what.getClass ());
+	    throw new XmlRpcException (0, "Java class not supported in XML-RPC: " + what.getClass ());
 	writer.endElement ("value");
     }
 
@@ -542,6 +542,7 @@ public abstract class XmlRpc extends HandlerBase {
     	
 	public XmlWriter (StringBuffer buf, String enc) {
 	    this.buf = buf;
+	    buf.setLength (0);
 	    this.enc = enc;
 	    // get name of encoding for XML prolog
 	    String encName = encodings.getProperty (enc, enc);
diff --git a/src/helma/xmlrpc/XmlRpcClient.java b/src/helma/xmlrpc/XmlRpcClient.java
index e8c208b8..1b1bf149 100644
--- a/src/helma/xmlrpc/XmlRpcClient.java
+++ b/src/helma/xmlrpc/XmlRpcClient.java
@@ -24,6 +24,8 @@ public class XmlRpcClient implements XmlRpcHandler {
     // pool of worker instances
     Stack pool = new Stack ();
     int workers = 0;
+    int asyncWorkers = 0;
+
 
     // average roundtrip of this method call. This is used to decide if
     // additional threads are needed or not in async mode
@@ -82,7 +84,7 @@ public class XmlRpcClient implements XmlRpcHandler {
      * @exception IOException: If the call could not be made because of lower level problems.
      */
     public Object execute (String method, Vector params) throws XmlRpcException, IOException {
-    	Worker worker = getWorker ();
+    	Worker worker = getWorker (false);
 	long start = System.currentTimeMillis ();
 	try {
     	    Object retval =  worker.execute (method, params);
@@ -90,7 +92,7 @@ public class XmlRpcClient implements XmlRpcHandler {
 	    roundtrip = (int) ((roundtrip*4)+(end-start))/5;
 	    return retval;
 	} finally {
-	    releaseWorker (worker);
+	    releaseWorker (worker, false);
 	}
     }
 
@@ -101,13 +103,13 @@ public class XmlRpcClient implements XmlRpcHandler {
      * 
      */
     public void executeAsync (String method, Vector params, AsyncCallback callback) {
-	if (workers > 2) {
+	if (asyncWorkers > 2) {
 	    enqueue (method, params, callback);
 	    return;
 	}
     	Worker worker = null;
 	try {
-	    worker = getWorker ();
+	    worker = getWorker (true);
     	    worker.executeAsync (method, params, callback);
 	} catch (IOException iox) {
 	    // make a queued worker that doesn't run immediately
@@ -116,14 +118,20 @@ public class XmlRpcClient implements XmlRpcHandler {
     }
     
 
-    synchronized Worker getWorker () throws IOException {
+    synchronized Worker getWorker (boolean async) throws IOException {
 	try {
 	    Worker w =  (Worker) pool.pop ();
-	     workers += 1;
+	    if (async)
+	        asyncWorkers += 1;
+	    else
+	        workers += 1;
 	     return w;
 	} catch (EmptyStackException x) {
 	    if (workers < maxThreads) {
-	        workers += 1;
+	        if (async)
+	            asyncWorkers += 1;
+	        else
+	            workers += 1;
 	        return new Worker ();
 	    }
 	    throw new IOException ("XML-RPC System overload");
@@ -133,12 +141,15 @@ public class XmlRpcClient implements XmlRpcHandler {
    /**
      * Release possibly big per-call object references to allow them to be garbage collected
      */
-    synchronized void releaseWorker (Worker w) {
+    synchronized void releaseWorker (Worker w, boolean async) {
 	w.result = null;
 	w.call = null;
 	if (pool.size() < 20 && !w.fault)
 	    pool.push (w);
-	workers -= 1;
+	if (async)
+	    asyncWorkers -= 1;
+	else
+	    workers -= 1;
     }
 
 
@@ -155,8 +166,8 @@ public class XmlRpcClient implements XmlRpcHandler {
     synchronized CallData dequeue () {
 	if (first == null)
 	    return null;
-	// if (workers > 2 && workers*4 > roundtrip)
-	//     return null;
+	if (asyncWorkers > 4 && asyncWorkers*4 > roundtrip)
+	    return null;
 	CallData call = first;
 	if (first == last)
 	    first = last = null;
@@ -187,11 +198,9 @@ public class XmlRpcClient implements XmlRpcHandler {
     public void run () {
 	while (call != null) {
 	    runAsync (call.method, call.params, call.callback);
-// System.err.println (workers+" ---- "+ roundtrip);
 	    call = dequeue ();
-	    // if (call != null) System.err.print (".");
 	}
-	releaseWorker (this);
+	releaseWorker (this, false);
     }
 
     void runAsync (String method, Vector params, AsyncCallback callback) {
@@ -203,8 +212,9 @@ public class XmlRpcClient implements XmlRpcHandler {
 	    if (callback != null)
 	        callback.handleResult (res, url, method);
 	} catch (Exception x) {
-                 if (callback != null)
+                 if (callback != null) try {
 	        callback.handleError (x, url, method);
+	    } catch (Exception ignore) {}
 	}
 	long end = System.currentTimeMillis ();
 	roundtrip = (int) ((roundtrip*4)+(end-start))/5;
@@ -218,8 +228,7 @@ public class XmlRpcClient implements XmlRpcHandler {
 
 	    if (strbuf == null)
 	        strbuf = new StringBuffer ();
-	    else
-	        strbuf.setLength (0);
+
 	    XmlWriter writer = new XmlWriter (strbuf);
 	    writeRequest (writer, method, params);
 	    byte[] request = writer.getBytes();
@@ -272,7 +281,7 @@ public class XmlRpcClient implements XmlRpcHandler {
     /**
      * Generate an XML-RPC request from a method name and a parameter vector.
      */
-    void writeRequest (XmlWriter writer, String method, Vector params) throws IOException {
+    void writeRequest (XmlWriter writer, String method, Vector params) throws IOException, XmlRpcException {
 	writer.startElement ("methodCall");
 
 	writer.startElement ("methodName");
diff --git a/src/helma/xmlrpc/XmlRpcClientLite.java b/src/helma/xmlrpc/XmlRpcClientLite.java
index 669c97e6..7dced08b 100644
--- a/src/helma/xmlrpc/XmlRpcClientLite.java
+++ b/src/helma/xmlrpc/XmlRpcClientLite.java
@@ -41,14 +41,20 @@ public class XmlRpcClientLite extends XmlRpcClient {
     }
 
 
-   synchronized Worker getWorker () throws IOException {
+   synchronized Worker getWorker (boolean async) throws IOException {
 	try {
 	    Worker w = (Worker) pool.pop ();
-	    workers += 1;
+	    if (async)
+	        asyncWorkers += 1;
+	    else
+	        workers += 1;
 	    return w;
 	} catch (EmptyStackException x) {
 	    if (workers < maxThreads) {
-	        workers += 1;
+	        if (async)
+	            asyncWorkers += 1;
+	        else
+	            workers += 1;
 	        return new LiteWorker ();
 	    }
 	    throw new IOException ("XML-RPC System overload");
diff --git a/src/helma/xmlrpc/XmlRpcServer.java b/src/helma/xmlrpc/XmlRpcServer.java
index 0d347ee1..e8d52adb 100644
--- a/src/helma/xmlrpc/XmlRpcServer.java
+++ b/src/helma/xmlrpc/XmlRpcServer.java
@@ -96,8 +96,7 @@ public class XmlRpcServer {
 	inParams = new Vector ();
 	if (strbuf == null)
 	    strbuf = new StringBuffer ();
-	else
-	    strbuf.setLength (0);
+
 	long now = System.currentTimeMillis ();
 
     	try {
@@ -150,7 +149,11 @@ public class XmlRpcServer {
 	    String message = x.toString ();
 	    // check if XmlRpcException was thrown so we can get an error code
 	    int code = x instanceof XmlRpcException ? ((XmlRpcException) x).code : 0;
-	    writeError (code, message, writer);
+	    try {
+	        writeError (code, message, writer);
+	    } catch (XmlRpcException xrx) {
+	        // won't happen, we just sent a struct with an int and a string
+	    }
 	    try {
 	        result = writer.getBytes ();
 	    } catch (UnsupportedEncodingException encx) {
@@ -173,7 +176,7 @@ public class XmlRpcServer {
     /**
      * Writes an XML-RPC response to the XML writer.
      */
-    void writeResponse (Object param, XmlWriter writer) {
+    void writeResponse (Object param, XmlWriter writer) throws XmlRpcException {
 	writer.startElement ("methodResponse");
 	// if (param == null) param = ""; // workaround for Frontier bug
 	writer.startElement ("params");
@@ -187,7 +190,7 @@ public class XmlRpcServer {
      /**
      * Writes an XML-RPC error response to the XML writer.
      */
-     void writeError (int code, String message, XmlWriter writer) {
+     void writeError (int code, String message, XmlWriter writer) throws XmlRpcException {
     	// System.err.println ("error: "+message);
 	Hashtable h = new Hashtable ();
 	h.put ("faultCode", new Integer (code));