include current thread-name as well as level in logger's formatted message e.g. :

kares · kares · commit f0e89f41c815 · 2016-04-19T15:23:11.000+02:00
2015-11-04T11:29:41.759+01:00 [main] INFO SampleLogger : hello world
diff --git a/core/src/main/java/org/jruby/util/log/OutputStreamLogger.java b/core/src/main/java/org/jruby/util/log/OutputStreamLogger.java
@@ -120,12 +120,12 @@ public void setDebugEnable(boolean debug) {
 
     protected void write(String message, String level, Object[] args) {
         CharSequence suble = substitute(message, args);
-        stream.println(formatMessage(suble.toString()));
+        stream.println(formatMessage(suble, level));
     }
 
     protected void write(String message, String level, Throwable throwable) {
         synchronized (stream) {
-            stream.println(formatMessage(message));
+            stream.println(formatMessage(message, level));
             //if ( message == null || message.length() > 0 ) stream.print(' ');
             writeStackTrace(stream, throwable);
         }
@@ -139,12 +139,17 @@ protected static void writeStackTrace(PrintStream stream, Throwable throwable) {
         throwable.printStackTrace(stream);
     }
 
-    protected String formatMessage(CharSequence message) {
-        return new StringBuilder()
+    protected String formatMessage(CharSequence message, String level) {
+        // 2015-11-04T11:29:41.759+01:00 [main] INFO SampleLogger : hello world
+        return new StringBuilder(64)
             .append(new DateTime(System.currentTimeMillis()))
-            .append(": ")
+            .append(' ')
+            .append('[').append(Thread.currentThread().getName()).append(']')
+            .append(' ')
+            .append(level)
+            .append(' ')
             .append(loggerName)
-            .append(": ")
+            .append(" : ")
             .append(message)
             .toString();
     }
diff --git a/core/src/main/java/org/jruby/util/log/StandardErrorLogger.java b/core/src/main/java/org/jruby/util/log/StandardErrorLogger.java
@@ -50,7 +50,7 @@ protected void write(String message, String level, Object[] args) {
         if ( stream == null ) stream = System.err;
 
         CharSequence suble = substitute(message, args);
-        stream.println(formatMessage(suble.toString()));
+        stream.println(formatMessage(suble, level));
     }
 
     @Override
@@ -61,7 +61,7 @@ protected void write(String message, String level, Throwable throwable) {
         if ( stream == null ) stream = System.err;
 
         synchronized (stream) {
-            stream.println(formatMessage(message));
+            stream.println(formatMessage(message, level));
             writeStackTrace(stream, throwable);
         }
     }
diff --git a/core/src/test/java/org/jruby/util/log/OutputStreamLoggerTest.java b/core/src/test/java/org/jruby/util/log/OutputStreamLoggerTest.java
@@ -83,6 +83,28 @@ public void testWithDebuggingEnabled() {
         }
     }
 
+    @Test
+    public void testIncludesLevel() {
+        final boolean debug = logger.isDebugEnabled();
+        try {
+            logger.setDebugEnable(true);
+            logger.debug("{} message", "a debug");
+            assertStreamNotEmpty();
+            assertStreamEndsWith("DEBUG OutputStreamLoggerTest : a debug message");
+
+            logger.info("hello!");
+            assertStreamNotEmpty();
+            assertStreamEndsWith("INFO OutputStreamLoggerTest : hello!");
+
+            logger.warn("red-{}", "alert");
+            assertStreamNotEmpty();
+            assertStreamEndsWith("WARN OutputStreamLoggerTest : red-alert");
+        }
+        finally {
+            logger.setDebugEnable(debug);
+        }
+    }
+
     @Test
     public void testWithException() {
         logger.error("debug-test-x", new RuntimeException("42"));

Original file line number	Diff line number	Diff line change
`@@ -50,7 +50,7 @@ protected void write(String message, String level, Object[] args) {`
`50`	`50`	`if ( stream == null ) stream = System.err;`
`51`	`51`
`52`	`52`	`CharSequence suble = substitute(message, args);`
`53`		`- stream.println(formatMessage(suble.toString()));`
	`53`	`+ stream.println(formatMessage(suble, level));`
`54`	`54`	`}`
`55`	`55`
`56`	`56`	`@Override`
`@@ -61,7 +61,7 @@ protected void write(String message, String level, Throwable throwable) {`
`61`	`61`	`if ( stream == null ) stream = System.err;`
`62`	`62`
`63`	`63`	`synchronized (stream) {`
`64`		`- stream.println(formatMessage(message));`
	`64`	`+ stream.println(formatMessage(message, level));`
`65`	`65`	`writeStackTrace(stream, throwable);`
`66`	`66`	`}`
`67`	`67`	`}`