revise the RabitTracker Impl

delete FileUtil class

fix bugs

.gitignore

@@ -78,5 +78,4 @@ tags
 *.iml
 *.class
 target
-
 *.swp

dmlc-core

@@ -1 +1 @@
-Subproject commit 3f6ff43d3976d5b6d5001608b0e3e526ecde098f
+Subproject commit 71360023dba458bdc9f1bc6f4309c1a107cb83a0

jvm-packages/xgboost4j-demo/src/main/java/ml/dmlc/xgboost4j/demo/DistTrain.java

@@ -20,16 +20,17 @@ public class DistTrain {
   private Map<String, String> envs = null;
 
   private class Worker implements Runnable {
-    private int worker_id;
-    Worker(int worker_id) {
-      this.worker_id = worker_id;
+    private final int workerId;
+
+    Worker(int workerId) {
+      this.workerId = workerId;
     }
 
     public void run() {
       try {
         Map<String, String> worker_env = new HashMap<String, String>(envs);
 
-        worker_env.put("DMLC_TASK_ID", new Integer(worker_id).toString());
+        worker_env.put("DMLC_TASK_ID", String.valueOf(workerId));
         // always initialize rabit module before training.
         Rabit.init(worker_env);
 
@@ -44,7 +45,6 @@ public class DistTrain {
         params.put("nthread", 2);
         params.put("objective", "binary:logistic");
 
-
         HashMap<String, DMatrix> watches = new HashMap<String, DMatrix>();
         watches.put("train", trainMat);
         watches.put("test", testMat);
@@ -63,14 +63,15 @@ public class DistTrain {
     }
   }
 
-  void start(int nworker) throws IOException, XGBoostError, InterruptedException {
-    RabitTracker tracker = new RabitTracker(nworker);
-    tracker.start();
-    envs = tracker.getWorkerEnvs();
-    for (int i = 0; i < nworker; ++i) {
-      new Thread(new Worker(i)).start();
+  void start(int nWorkers) throws IOException, XGBoostError, InterruptedException {
+    RabitTracker tracker = new RabitTracker(nWorkers);
+    if (tracker.start()) {
+      envs = tracker.getWorkerEnvs();
+      for (int i = 0; i < nWorkers; ++i) {
+        new Thread(new Worker(i)).start();
+      }
+      tracker.waitFor();
     }
-    tracker.waitFor();
   }
 
   public static void main(String[] args) throws IOException, XGBoostError, InterruptedException {

jvm-packages/xgboost4j/src/main/java/ml/dmlc/xgboost4j/FileUtil.java

@@ -1,78 +0,0 @@
-package ml.dmlc.xgboost4j;
-
-
-import java.io.*;
-import java.io.IOException;
-
-/**
- * Auxiliary utils to
- */
-class FileUtil {
-  /**
-   * Create a temp file that copies the resource from current JAR archive
-   * <p/>
-   * The file from JAR is copied into system temp file.
-   * The temporary file is deleted after exiting.
-   * Method uses String as filename because the pathname is "abstract", not system-dependent.
-   * <p/>
-   * The restrictions of {@link File#createTempFile(java.lang.String, java.lang.String)} apply to
-   * {@code path}.
-   * @param path Path to the resources in the jar
-   * @return The created temp file.
-   * @throws IOException
-   * @throws IllegalArgumentException
-   */
-  static File createTempFileFromResource(String path) throws IOException, IllegalArgumentException {
-    // Obtain filename from path
-    if (!path.startsWith("/")) {
-      throw new IllegalArgumentException("The path has to be absolute (start with '/').");
-    }
-
-    String[] parts = path.split("/");
-    String filename = (parts.length > 1) ? parts[parts.length - 1] : null;
-
-    // Split filename to prexif and suffix (extension)
-    String prefix = "";
-    String suffix = null;
-    if (filename != null) {
-      parts = filename.split("\\.", 2);
-      prefix = parts[0];
-      suffix = (parts.length > 1) ? "." + parts[parts.length - 1] : null; // Thanks, davs! :-)
-    }
-
-    // Check if the filename is okay
-    if (filename == null || prefix.length() < 3) {
-      throw new IllegalArgumentException("The filename has to be at least 3 characters long.");
-    }
-    // Prepare temporary file
-    File temp = File.createTempFile(prefix, suffix);
-    temp.deleteOnExit();
-
-    if (!temp.exists()) {
-      throw new FileNotFoundException("File " + temp.getAbsolutePath() + " does not exist.");
-    }
-
-    // Prepare buffer for data copying
-    byte[] buffer = new byte[1024];
-    int readBytes;
-
-    // Open and check input stream
-    InputStream is = NativeLibLoader.class.getResourceAsStream(path);
-    if (is == null) {
-      throw new FileNotFoundException("File " + path + " was not found inside JAR.");
-    }
-
-    // Open output stream and copy data between source file in JAR and the temporary file
-    OutputStream os = new FileOutputStream(temp);
-    try {
-      while ((readBytes = is.read(buffer)) != -1) {
-        os.write(buffer, 0, readBytes);
-      }
-    } finally {
-      // If read/write fails, close streams safely before throwing an exception
-      os.close();
-      is.close();
-    }
-    return temp;
-  }
-}

jvm-packages/xgboost4j/src/main/java/ml/dmlc/xgboost4j/NativeLibLoader.java

@@ -21,8 +21,6 @@ import java.lang.reflect.Field;
 import org.apache.commons.logging.Log;
 import org.apache.commons.logging.LogFactory;
 
-import ml.dmlc.xgboost4j.FileUtil;
-
 
 /**
  * class to load native library
@@ -64,9 +62,78 @@ class NativeLibLoader {
    * three characters
    */
   private static void loadLibraryFromJar(String path) throws IOException, IllegalArgumentException{
-    File temp = FileUtil.createTempFileFromResource(path);
+    String temp = createTempFileFromResource(path);
     // Finally, load the library
-    System.load(temp.getAbsolutePath());
+    System.load(temp);
+  }
+
+  /**
+   * Create a temp file that copies the resource from current JAR archive
+   * <p/>
+   * The file from JAR is copied into system temp file.
+   * The temporary file is deleted after exiting.
+   * Method uses String as filename because the pathname is "abstract", not system-dependent.
+   * <p/>
+   * The restrictions of {@link File#createTempFile(java.lang.String, java.lang.String)} apply to
+   * {@code path}.
+   * @param path Path to the resources in the jar
+   * @return The created temp file.
+   * @throws IOException
+   * @throws IllegalArgumentException
+   */
+  static String createTempFileFromResource(String path) throws
+          IOException, IllegalArgumentException {
+    // Obtain filename from path
+    if (!path.startsWith("/")) {
+      throw new IllegalArgumentException("The path has to be absolute (start with '/').");
+    }
+
+    String[] parts = path.split("/");
+    String filename = (parts.length > 1) ? parts[parts.length - 1] : null;
+
+    // Split filename to prexif and suffix (extension)
+    String prefix = "";
+    String suffix = null;
+    if (filename != null) {
+      parts = filename.split("\\.", 2);
+      prefix = parts[0];
+      suffix = (parts.length > 1) ? "." + parts[parts.length - 1] : null; // Thanks, davs! :-)
+    }
+
+    // Check if the filename is okay
+    if (filename == null || prefix.length() < 3) {
+      throw new IllegalArgumentException("The filename has to be at least 3 characters long.");
+    }
+    // Prepare temporary file
+    File temp = File.createTempFile(prefix, suffix);
+    temp.deleteOnExit();
+
+    if (!temp.exists()) {
+      throw new FileNotFoundException("File " + temp.getAbsolutePath() + " does not exist.");
+    }
+
+    // Prepare buffer for data copying
+    byte[] buffer = new byte[1024];
+    int readBytes;
+
+    // Open and check input stream
+    InputStream is = NativeLibLoader.class.getResourceAsStream(path);
+    if (is == null) {
+      throw new FileNotFoundException("File " + path + " was not found inside JAR.");
+    }
+
+    // Open output stream and copy data between source file in JAR and the temporary file
+    OutputStream os = new FileOutputStream(temp);
+    try {
+      while ((readBytes = is.read(buffer)) != -1) {
+        os.write(buffer, 0, readBytes);
+      }
+    } finally {
+      // If read/write fails, close streams safely before throwing an exception
+      os.close();
+      is.close();
+    }
+    return temp.getAbsolutePath();
   }
 
   /**
@@ -84,8 +151,9 @@ class NativeLibLoader {
       try {
         String libraryFromJar = nativeResourcePath + System.mapLibraryName(libName);
         loadLibraryFromJar(libraryFromJar);
-      } catch (IOException e1) {
-        throw e1;
+      } catch (IOException ioe) {
+        logger.error("failed to load library from both native path and jar");
+        throw ioe;
       }
     }
   }

jvm-packages/xgboost4j/src/main/java/ml/dmlc/xgboost4j/RabitTracker.java

@@ -5,6 +5,7 @@ package ml.dmlc.xgboost4j;
 import java.io.*;
 import java.util.HashMap;
 import java.util.Map;
+import java.util.concurrent.atomic.AtomicReference;
 
 import org.apache.commons.logging.Log;
 import org.apache.commons.logging.LogFactory;
@@ -16,45 +17,40 @@ public class RabitTracker {
   // Maybe per tracker logger?
   private static final Log logger = LogFactory.getLog(RabitTracker.class);
   // tracker python file.
-  private static File tracker_py = null;
+  private static String tracker_py = null;
   // environment variable to be pased.
   private Map<String, String> envs = new HashMap<String, String>();
   // number of workers to be submitted.
   private int num_workers;
-  // child process
-  private  Process process = null;
-  // logger thread
-  private Thread logger_thread = null;
-
-  //load native library
-  static {
-    try {
-      initTrackerPy();
-    } catch (IOException ex) {
-      logger.error("load tracker library failed.");
-      logger.error(ex);
-    }
-  }
+  private AtomicReference<Process> trackerProcess = new AtomicReference<Process>();
 
   /**
    * Tracker logger that logs output from tracker.
    */
-  private class TrackerLogger implements Runnable {
+  private class TrackerProcessLogger implements Runnable {
     public void run() {
-      BufferedReader reader = new BufferedReader(new InputStreamReader(process.getErrorStream()));
+
+      Log trackerProcessLogger = LogFactory.getLog(TrackerProcessLogger.class);
+      BufferedReader reader = new BufferedReader(new InputStreamReader(
+              trackerProcess.get().getErrorStream()));
       String line;
       try {
         while ((line = reader.readLine()) != null) {
-          logger.info(line);
+          trackerProcessLogger.info(line);
         }
       } catch (IOException ex) {
-        logger.error(ex.toString());
+        trackerProcessLogger.error(ex.toString());
       }
     }
   }
 
-  private static synchronized void initTrackerPy() throws IOException {
-    tracker_py = FileUtil.createTempFileFromResource("/tracker.py");
+  private void initTrackerPy() throws IOException {
+    try {
+      tracker_py = NativeLibLoader.createTempFileFromResource("/tracker.py");
+    } catch (IOException ioe) {
+      logger.trace("cannot access tracker python script");
+      throw ioe;
+    }
   }
 
 
@@ -70,29 +66,71 @@ public class RabitTracker {
     return envs;
   }
 
-  public void start() throws IOException {
-    process = Runtime.getRuntime().exec("python " + tracker_py.getAbsolutePath() +
-            " --num-workers=" + new Integer(num_workers).toString());
-    BufferedReader reader = new BufferedReader(new InputStreamReader(process.getInputStream()));
-    assert reader.readLine().trim().equals("DMLC_TRACKER_ENV_START");
-    String line;
-    while ((line = reader.readLine()) != null) {
-      if (line.trim().equals("DMLC_TRACKER_ENV_END")) {
-        break;
-      }
-      String []sep = line.split("=");
-      if (sep.length == 2) {
-        envs.put(sep[0], sep[1]);
+  private void loadEnvs(InputStream ins) throws IOException {
+    try {
+      BufferedReader reader = new BufferedReader(new InputStreamReader(ins));
+      assert reader.readLine().trim().equals("DMLC_TRACKER_ENV_START");
+      String line;
+      while ((line = reader.readLine()) != null) {
+        if (line.trim().equals("DMLC_TRACKER_ENV_END")) {
+          break;
+        }
+        String[] sep = line.split("=");
+        if (sep.length == 2) {
+          envs.put(sep[0], sep[1]);
+        }
       }
+      reader.close();
+    } catch (IOException ioe){
+      logger.error("cannot get runtime configuration from tracker process");
+      ioe.printStackTrace();
+      throw ioe;
     }
-    logger.debug("Tracker started, with env=" + envs.toString());
-    // also start a tracker logger
-    logger_thread = new Thread(new TrackerLogger());
-    logger_thread.setDaemon(true);
-    logger_thread.start();
   }
 
-  public void waitFor() throws InterruptedException {
-    process.waitFor();
+  private boolean startTrackerProcess() {
+    try {
+      initTrackerPy();
+      trackerProcess.set(Runtime.getRuntime().exec("python " + tracker_py +
+              " --num-workers=" + String.valueOf(num_workers)));
+      loadEnvs(trackerProcess.get().getInputStream());
+      return true;
+    } catch (IOException ioe) {
+      ioe.printStackTrace();
+      return false;
+    }
+  }
+
+  private void stop() {
+    if (trackerProcess.get() != null) {
+      trackerProcess.get().destroy();
+    }
+  }
+
+  public boolean start() {
+    if (startTrackerProcess()) {
+      logger.debug("Tracker started, with env=" + envs.toString());
+      // also start a tracker logger
+      Thread logger_thread = new Thread(new TrackerProcessLogger());
+      logger_thread.setDaemon(true);
+      logger_thread.start();
+      return true;
+    } else {
+      logger.error("FAULT: failed to start tracker process");
+      stop();
+      return false;
+    }
+  }
+
+  public void waitFor() {
+    try {
+      trackerProcess.get().waitFor();
+      logger.info("Tracker Process ends with exit code " + trackerProcess.get().exitValue());
+      stop();
+    } catch (InterruptedException e) {
+      // we should not get here as RabitTracker is accessed in the main thread
+      e.printStackTrace();
+      logger.error("the RabitTracker thread is terminated unexpectedly");
+    }
   }
 }

rabit

@@ -1 +1 @@
-Subproject commit be50e7b63224b9fb7ff94ce34df9f8752ef83043
+Subproject commit 1392e9f3da59bd5602ddebee944dd8fb5c6507b0