Index: logback-classic/src/test/java/ch/qos/logback/classic/issue/lbclassic36/SelectiveDateFormattingRunnable.java
===================================================================
--- logback-classic/src/test/java/ch/qos/logback/classic/issue/lbclassic36/SelectiveDateFormattingRunnable.java	(revision 2293)
+++ logback-classic/src/test/java/ch/qos/logback/classic/issue/lbclassic36/SelectiveDateFormattingRunnable.java	Wed Jun 17 12:39:31 CEST 2009
@@ -1,6 +1,8 @@
 package ch.qos.logback.classic.issue.lbclassic36;
 
 import java.text.SimpleDateFormat;
+import java.util.concurrent.atomic.AtomicLong;
+
 import org.joda.time.format.DateTimeFormat;
 import org.joda.time.format.DateTimeFormatter;
 
@@ -22,7 +24,7 @@
   }
 
   FormattingModel model;
-  static long CACHE = 0;
+  static AtomicLong CACHE = new AtomicLong();
 
   static SimpleDateFormat SDF = new SimpleDateFormat(ISO8601_PATTERN);
   static final DateTimeFormatter JODA = DateTimeFormat
@@ -46,10 +48,9 @@
   void sdfRun() {
 
     for (;;) {
-      synchronized (SDF) {
-        long now = System.currentTimeMillis();
+      long now = System.currentTimeMillis();
-        if (CACHE != now) {
-          CACHE = now;
+      if(isCacheStale(now)) {
+        synchronized (SDF) {
           SDF.format(now);
         }
       }
@@ -74,12 +75,9 @@
   }
   
   private static boolean isCacheStale(long now) {
-    synchronized (JODA) {
-      if (CACHE != now) {
-        CACHE = now;
+    if(CACHE.getAndSet(now) != now) {
-        return true;
-      }
+      return true;
+    }
-    }
     return false;
   }