improved thread death error diagnostics.

git-svn-id: https://hudson.dev.java.net/svn/hudson/trunk/hudson/main@4893 71c3de6d-444a-0410-be80-ed276b4c234a

core/src/main/java/hudson/Functions.java

@@ -27,6 +27,8 @@ import javax.servlet.http.HttpServletRequest;
 import javax.servlet.http.HttpServletResponse;
 import java.io.File;
 import java.io.IOException;
+import java.io.StringWriter;
+import java.io.PrintWriter;
 import java.lang.management.LockInfo;
 import java.lang.management.ManagementFactory;
 import java.lang.management.MonitorInfo;
@@ -622,4 +624,10 @@ public class Functions {
         if(b==null) return true;
         return b;
     }
+
+    public static String printThrowable(Throwable t) {
+        StringWriter sw = new StringWriter();
+        t.printStackTrace(new PrintWriter(sw));
+        return sw.toString();
+    }
 }