Class CloseableThreadLocal

  extended by org.apache.lucene.util.CloseableThreadLocal

public class CloseableThreadLocal
extends Object

Java's builtin ThreadLocal has a serious flaw: it can take an arbitrarily long amount of time to dereference the things you had stored in it, even once the ThreadLocal instance itself is no longer referenced. This is because there is single, master map stored for each thread, which all ThreadLocals share, and that master map only periodically purges "stale" entries. While not technically a memory leak, because eventually the memory will be reclaimed, it can take a long time and you can easily hit OutOfMemoryError because from the GC's standpoint the stale entries are not reclaimable. This class works around that, by only enrolling WeakReference values into the ThreadLocal, and separately holding a hard reference to each stored value. When you call close(), these hard references are cleared and then GC is freely able to reclaim space by objects stored in it.

Constructor Summary
Method Summary
 void close()
 Object get()
protected  Object initialValue()
 void set(Object object)
Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail


public CloseableThreadLocal()
Method Detail


protected Object initialValue()


public Object get()


public void set(Object object)


public void close()

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