[GitHub] wu-sheng edited a comment on issue #2016: fix classloader dead lock in jdk7+

[GitBox <gi...@apache.org>]

wu-sheng edited a comment on issue #2016: fix classloader dead lock in jdk7+
URL: https://github.com/apache/incubator-skywalking/pull/2016#issuecomment-445128525
 
 
   When I dive into the `ClassLoader`, from jvm7, if other class loaders run in parallel mode, and accidentally they ask AgentClassLoader to init a plugin interceptor concurrently. May trigger this lock. 
   
   The related codes are here
   ```
       // This method is invoked by the virtual machine to load a class.
       private Class<?> loadClassInternal(String name)
           throws ClassNotFoundException
       {
           // For backward compatibility, explicitly lock on 'this' when
           // the current class loader is not parallel capable.
           if (parallelLockMap == null) {
               synchronized (this) {
                    return loadClass(name);
               }
           } else {
               return loadClass(name);
           }
       }
   ```
   
   The deadlock info is here
   
   ![image](https://user-images.githubusercontent.com/5441976/49629641-75175f00-fa25-11e8-83f4-0266e85c0e59.png)
   

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