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Fix memory leak in ConcurrentReferenceHashMap 

Update ConcurrentReferenceHashMap to protect against references that
have been garbage collected but for some reason do not appear as a
`pollForPurge` result.

Also added purgeUnreferencedEntries() method to allow for programmatic
cleanup.

Issue: SPR-11440
This commit is contained in:
Phillip Webb 2014-02-18 15:05:28 -08:00
parent fe6a9826c5
commit 2b4c81e642
1 changed files with 18 additions and 3 deletions
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21
spring-core/src/main/java/org/springframework/util/ConcurrentReferenceHashMap.java
View File

@ -338,6 +338,19 @@ public class ConcurrentReferenceHashMap<K, V> extends AbstractMap<K, V> implemen
} }
} }
/**
* Remove any entries that have been garbage collected and are no longer referenced.
* Under normal circumstances garbage collected entries are automatically purged as
* items are added or removed from the Map. This method can be used to force a purge,
* and is useful when the Map is read frequently but updated less often.
*/
public void purgeUnreferencedEntries() {
for (Segment segment : this.segments) {
segment.restructureIfNecessary(false);
}
}
@Override @Override
public int size() { public int size() {
int size = 0; int size = 0;
@ -512,7 +525,7 @@ public class ConcurrentReferenceHashMap<K, V> extends AbstractMap<K, V> implemen
* references that have been garbage collected. * references that have been garbage collected.
* @param allowResize if resizing is permitted * @param allowResize if resizing is permitted
*/ */
private void restructureIfNecessary(boolean allowResize) { protected final void restructureIfNecessary(boolean allowResize) {
boolean needsResize = ((this.count > 0) && (this.count >= this.resizeThreshold)); boolean needsResize = ((this.count > 0) && (this.count >= this.resizeThreshold));
Reference<K, V> reference = this.referenceManager.pollForPurge(); Reference<K, V> reference = this.referenceManager.pollForPurge();
if ((reference != null) || (needsResize && allowResize)) { if ((reference != null) || (needsResize && allowResize)) {
@ -550,7 +563,7 @@ public class ConcurrentReferenceHashMap<K, V> extends AbstractMap<K, V> implemen
restructured[i] = null; restructured[i] = null;
} }
while (reference != null) { while (reference != null) {
if (!toPurge.contains(reference)) { if (!toPurge.contains(reference) && (reference.get() != null)) {
int index = getIndex(reference.getHash(), restructured); int index = getIndex(reference.getHash(), restructured);
restructured[index] = this.referenceManager.createReference( restructured[index] = this.referenceManager.createReference(
reference.get(), reference.getHash(), reference.get(), reference.getHash(),
@ -564,7 +577,7 @@ public class ConcurrentReferenceHashMap<K, V> extends AbstractMap<K, V> implemen
if (resizing) { if (resizing) {
setReferences(restructured); setReferences(restructured);
} }
this.count = countAfterRestructure; this.count = Math.max(countAfterRestructure, 0);
} finally { } finally {
unlock(); unlock();
} }
@ -974,6 +987,7 @@ public class ConcurrentReferenceHashMap<K, V> extends AbstractMap<K, V> implemen
enqueue(); enqueue();
clear(); clear();
} }
} }
@ -1007,6 +1021,7 @@ public class ConcurrentReferenceHashMap<K, V> extends AbstractMap<K, V> implemen
enqueue(); enqueue();
clear(); clear();
} }
} }
} }