org.apache.lucene.util
Class CloseableThreadLocal

java.lang.Object
  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 reclaimaible. 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

CloseableThreadLocal()

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

CloseableThreadLocal

public CloseableThreadLocal()

Method Detail

initialValue

protected Object initialValue()

get

public Object get()

set

public void set(Object object)

close

public void close()