====== Java ThreadLocal ======
  * [[https://docs.oracle.com/javase/8/docs/api/java/lang/ThreadLocal.html|ThreadLocal]]

  Each thread holds an implicit reference to its copy of a thread-local variable
  as long as the thread is alive and the ThreadLocal instance is accessible;
  after a thread goes away, all of its copies of thread-local instances are subject 
  to garbage collection (unless other references to these copies exist).
  
 ===== withInitialValue =====
  * 초기값을 생성하는 lambda 를 지정해두면 최초에 값이 없을 때에 적절한 초기값을 제공해준다.
  * ''remove()'' 를 호출해서 초기값이 없어진 상태에서 다시 ''get()''을 하면 ''withInitialValue''로 설정했다면 다시 초기값을 생성해서 반환해준다.


===== 참조 =====
  * [[http://stackoverflow.com/questions/17968803/threadlocal-memory-leak|java - ThreadLocal & Memory Leak]]