[Java] make java worker log file prefix (default to java-worker) conf…

…igurable (#33797)

For java worker, it's log file always being prefixed with "java-worker". And in python log_monitor.py, it hardcodes "java-worker*.log" to be polled for new log msg periodically. Some configs, like log_to_driver and RAY_BACKEND_LOG_LEVEL, don't prevent the log monitor from polling and publishing logs to gcs. To save some CPU cycle and network bandwidth, especially if there is large amount of logs produced from JVM, we can have an option. like a JVM system property, to set log file prefix for java worker instead of hard coded to "java-worker".

java/runtime/src/main/java/io/ray/runtime/util/LoggingUtil.java

@@ -79,7 +79,12 @@ public static synchronized void setupLogging(RayConfig rayConfig) {
       RootLoggerComponentBuilder rootLoggerBuilder = globalConfigBuilder.newAsyncRootLogger(level);
       rootLoggerBuilder.addAttribute("RingBufferSize", "1048576");
       final String javaWorkerLogName = "JavaWorkerLogToRollingFile";
-      String logFileName = "java-worker-" + jobIdHex + "-" + SystemUtil.pid();
+      String logFileName =
+          rayConfig.getInternalConfig().getString("ray.logging.file-prefix")
+              + "-"
+              + jobIdHex
+              + "-"
+              + SystemUtil.pid();
       setupLogger(
           globalConfigBuilder,
           rayConfig.logDir,

java/runtime/src/main/resources/ray.default.conf

@@ -89,6 +89,10 @@ ray {
     max-file-size: 500MB
     // Maximum number of backup files to keep around.
     max-backup-files: 10
+    // log file name prefix of default logger
+    // change it to something else other than "java-worker" if you dont want
+    // ray log monitor to poll and publish log to gcs from the log file
+    file-prefix: java-worker
 
     // Configuration for the customized loggers.
     // For example, if you want to customize the file name and the log pattern for a logger

java/runtime/src/test/java/io/ray/runtime/config/RayConfigTest.java

@@ -15,4 +15,14 @@ public void testCreateRayConfig() {
     Assert.assertEquals(
         Collections.singletonList("path/to/ray/job/resource/path"), rayConfig.codeSearchPath);
   }
+
+  @Test
+  public void testGetLogFilePrefix() {
+    String key = "ray.logging.file-prefix";
+    RayConfig rayConfig = RayConfig.create();
+    Assert.assertEquals("java-worker", rayConfig.getInternalConfig().getString(key));
+    System.setProperty(key, "raydp-java-worker");
+    rayConfig = RayConfig.create();
+    Assert.assertEquals("raydp-java-worker", rayConfig.getInternalConfig().getString(key));
+  }
 }