[HADOOP-11771] Configuration::getClassByNameOrNull synchronizes on a static object

• Type: Sub-task
• Status: Open
• Priority: Critical
• Resolution: Unresolved
• Component/s: conf, io, ipc
• Assignee: Unassigned
• Reporter: Gopal Vijayaraghavan
• Created: 28/Mar/15 04:08
• Updated: 14/Nov/15 06:37

Description

 IPC Client (1970436060) connection to cn106-10.l42scl.hortonworks.com/172.21.128.106:34530 from application_1442254312093_2976 [BLOCKED] [DAEMON]
org.apache.hadoop.conf.Configuration.getClassByNameOrNull(String) Configuration.java:2117
org.apache.hadoop.conf.Configuration.getClassByName(String) Configuration.java:2099
org.apache.hadoop.io.ObjectWritable.loadClass(Configuration, String) ObjectWritable.java:373
org.apache.hadoop.io.ObjectWritable.readObject(DataInput, ObjectWritable, Configuration) ObjectWritable.java:282
org.apache.hadoop.io.ObjectWritable.readFields(DataInput) ObjectWritable.java:77
org.apache.hadoop.ipc.Client$Connection.receiveRpcResponse() Client.java:1098
org.apache.hadoop.ipc.Client$Connection.run() Client.java:977

  private static final Map<ClassLoader, Map<String, WeakReference<Class<?>>>>
    CACHE_CLASSES = new WeakHashMap<ClassLoader, Map<String, WeakReference<Class<?>>>>();

...
 synchronized (CACHE_CLASSES) {
      map = CACHE_CLASSES.get(classLoader);
      if (map == null) {
        map = Collections.synchronizedMap(
          new WeakHashMap<String, WeakReference<Class<?>>>());
        CACHE_CLASSES.put(classLoader, map);
      }
    }

Issue Links

• is related to: HADOOP-10513 ReflectionUtils::CONSTRUCTOR_CACHE leaks class loaders