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LUCENE-7237: LRUQueryCache now prefers returning an uncached Scorer than waiting on a lock.

This commit is contained in:
Adrien Grand 2016-04-22 14:09:44 +02:00
parent 927a44881c
commit bf232d7635
2 changed files with 154 additions and 83 deletions
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3
lucene/CHANGES.txt
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@ -76,6 +76,9 @@ Optimizations
* LUCENE-7238: Explicitly disable the query cache in MemoryIndex#createSearcher.
(Adrien Grand)
* LUCENE-7237: LRUQueryCache now prefers returning an uncached Scorer than
waiting on a lock. (Adrien Grand)
Bug Fixes
* LUCENE-7127: Fix corner case bugs in GeoPointDistanceQuery. (Robert Muir)

232
lucene/core/src/java/org/apache/lucene/search/LRUQueryCache.java
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@ -29,6 +29,7 @@ import java.util.List;
import java.util.Map;
import java.util.Set;
import java.util.concurrent.atomic.AtomicBoolean;
import java.util.concurrent.locks.ReentrantLock;
import java.util.function.Predicate;
import org.apache.lucene.index.LeafReader.CoreClosedListener;
@ -112,6 +113,7 @@ public class LRUQueryCache implements QueryCache, Accountable {
// mostRecentlyUsedQueries. This is why write operations are performed under a lock
private final Set<Query> mostRecentlyUsedQueries;
private final Map<Object, LeafCache> cache;
private final ReentrantLock lock;
// these variables are volatile so that we do not need to sync reads
// but increments need to be performed under the lock
@ -134,6 +136,7 @@ public class LRUQueryCache implements QueryCache, Accountable {
uniqueQueries = new LinkedHashMap<>(16, 0.75f, true);
mostRecentlyUsedQueries = uniqueQueries.keySet();
cache = new IdentityHashMap<>();
lock = new ReentrantLock();
ramBytesUsed = 0;
}
@ -182,6 +185,7 @@ public class LRUQueryCache implements QueryCache, Accountable {
* @lucene.experimental
*/
protected void onHit(Object readerCoreKey, Query query) {
assert lock.isHeldByCurrentThread();
hitCount += 1;
}
@ -191,6 +195,7 @@ public class LRUQueryCache implements QueryCache, Accountable {
* @lucene.experimental
*/
protected void onMiss(Object readerCoreKey, Query query) {
assert lock.isHeldByCurrentThread();
assert query != null;
missCount += 1;
}
@ -203,6 +208,7 @@ public class LRUQueryCache implements QueryCache, Accountable {
* @lucene.experimental
*/
protected void onQueryCache(Query query, long ramBytesUsed) {
assert lock.isHeldByCurrentThread();
this.ramBytesUsed += ramBytesUsed;
}
@ -212,6 +218,7 @@ public class LRUQueryCache implements QueryCache, Accountable {
* @lucene.experimental
*/
protected void onQueryEviction(Query query, long ramBytesUsed) {
assert lock.isHeldByCurrentThread();
this.ramBytesUsed -= ramBytesUsed;
}
@ -223,6 +230,7 @@ public class LRUQueryCache implements QueryCache, Accountable {
* @lucene.experimental
*/
protected void onDocIdSetCache(Object readerCoreKey, long ramBytesUsed) {
assert lock.isHeldByCurrentThread();
cacheSize += 1;
cacheCount += 1;
this.ramBytesUsed += ramBytesUsed;
@ -235,6 +243,7 @@ public class LRUQueryCache implements QueryCache, Accountable {
* @lucene.experimental
*/
protected void onDocIdSetEviction(Object readerCoreKey, int numEntries, long sumRamBytesUsed) {
assert lock.isHeldByCurrentThread();
this.ramBytesUsed -= sumRamBytesUsed;
cacheSize -= numEntries;
}
@ -244,12 +253,14 @@ public class LRUQueryCache implements QueryCache, Accountable {
* @lucene.experimental
*/
protected void onClear() {
assert lock.isHeldByCurrentThread();
ramBytesUsed = 0;
cacheSize = 0;
}
/** Whether evictions are required. */
boolean requiresEviction() {
assert lock.isHeldByCurrentThread();
final int size = mostRecentlyUsedQueries.size();
if (size == 0) {
return false;
@ -258,7 +269,8 @@ public class LRUQueryCache implements QueryCache, Accountable {
}
}
synchronized DocIdSet get(Query key, LeafReaderContext context) {
DocIdSet get(Query key, LeafReaderContext context) {
assert lock.isHeldByCurrentThread();
assert key instanceof BoostQuery == false;
assert key instanceof ConstantScoreQuery == false;
final Object readerKey = context.reader().getCoreCacheKey();
@ -282,37 +294,42 @@ public class LRUQueryCache implements QueryCache, Accountable {
return cached;
}
synchronized void putIfAbsent(Query query, LeafReaderContext context, DocIdSet set) {
// under a lock to make sure that mostRecentlyUsedQueries and cache remain sync'ed
// we don't want to have user-provided queries as keys in our cache since queries are mutable
void putIfAbsent(Query query, LeafReaderContext context, DocIdSet set) {
assert query instanceof BoostQuery == false;
assert query instanceof ConstantScoreQuery == false;
Query singleton = uniqueQueries.putIfAbsent(query, query);
if (singleton == null) {
onQueryCache(singleton, LINKED_HASHTABLE_RAM_BYTES_PER_ENTRY + ramBytesUsed(query));
} else {
query = singleton;
// under a lock to make sure that mostRecentlyUsedQueries and cache remain sync'ed
lock.lock();
try {
Query singleton = uniqueQueries.putIfAbsent(query, query);
if (singleton == null) {
onQueryCache(singleton, LINKED_HASHTABLE_RAM_BYTES_PER_ENTRY + ramBytesUsed(query));
} else {
query = singleton;
}
final Object key = context.reader().getCoreCacheKey();
LeafCache leafCache = cache.get(key);
if (leafCache == null) {
leafCache = new LeafCache(key);
final LeafCache previous = cache.put(context.reader().getCoreCacheKey(), leafCache);
ramBytesUsed += HASHTABLE_RAM_BYTES_PER_ENTRY;
assert previous == null;
// we just created a new leaf cache, need to register a close listener
context.reader().addCoreClosedListener(new CoreClosedListener() {
@Override
public void onClose(Object ownerCoreCacheKey) {
clearCoreCacheKey(ownerCoreCacheKey);
}
});
}
leafCache.putIfAbsent(query, set);
evictIfNecessary();
} finally {
lock.unlock();
}
final Object key = context.reader().getCoreCacheKey();
LeafCache leafCache = cache.get(key);
if (leafCache == null) {
leafCache = new LeafCache(key);
final LeafCache previous = cache.put(context.reader().getCoreCacheKey(), leafCache);
ramBytesUsed += HASHTABLE_RAM_BYTES_PER_ENTRY;
assert previous == null;
// we just created a new leaf cache, need to register a close listener
context.reader().addCoreClosedListener(new CoreClosedListener() {
@Override
public void onClose(Object ownerCoreCacheKey) {
clearCoreCacheKey(ownerCoreCacheKey);
}
});
}
leafCache.putIfAbsent(query, set);
evictIfNecessary();
}
synchronized void evictIfNecessary() {
void evictIfNecessary() {
assert lock.isHeldByCurrentThread();
// under a lock to make sure that mostRecentlyUsedQueries and cache keep sync'ed
if (requiresEviction()) {
@ -337,31 +354,42 @@ public class LRUQueryCache implements QueryCache, Accountable {
/**
* Remove all cache entries for the given core cache key.
*/
public synchronized void clearCoreCacheKey(Object coreKey) {
final LeafCache leafCache = cache.remove(coreKey);
if (leafCache != null) {
ramBytesUsed -= HASHTABLE_RAM_BYTES_PER_ENTRY;
final int numEntries = leafCache.cache.size();
if (numEntries > 0) {
onDocIdSetEviction(coreKey, numEntries, leafCache.ramBytesUsed);
} else {
assert numEntries == 0;
assert leafCache.ramBytesUsed == 0;
public void clearCoreCacheKey(Object coreKey) {
lock.lock();
try {
final LeafCache leafCache = cache.remove(coreKey);
if (leafCache != null) {
ramBytesUsed -= HASHTABLE_RAM_BYTES_PER_ENTRY;
final int numEntries = leafCache.cache.size();
if (numEntries > 0) {
onDocIdSetEviction(coreKey, numEntries, leafCache.ramBytesUsed);
} else {
assert numEntries == 0;
assert leafCache.ramBytesUsed == 0;
}
}
} finally {
lock.unlock();
}
}
/**
* Remove all cache entries for the given query.
*/
public synchronized void clearQuery(Query query) {
final Query singleton = uniqueQueries.remove(query);
if (singleton != null) {
onEviction(singleton);
public void clearQuery(Query query) {
lock.lock();
try {
final Query singleton = uniqueQueries.remove(query);
if (singleton != null) {
onEviction(singleton);
}
} finally {
lock.unlock();
}
}
private void onEviction(Query singleton) {
assert lock.isHeldByCurrentThread();
onQueryEviction(singleton, LINKED_HASHTABLE_RAM_BYTES_PER_ENTRY + ramBytesUsed(singleton));
for (LeafCache leafCache : cache.values()) {
leafCache.remove(singleton);
@ -371,55 +399,70 @@ public class LRUQueryCache implements QueryCache, Accountable {
/**
* Clear the content of this cache.
*/
public synchronized void clear() {
cache.clear();
mostRecentlyUsedQueries.clear();
onClear();
public void clear() {
lock.lock();
try {
cache.clear();
mostRecentlyUsedQueries.clear();
onClear();
} finally {
lock.unlock();
}
}
// pkg-private for testing
synchronized void assertConsistent() {
if (requiresEviction()) {
throw new AssertionError("requires evictions: size=" + mostRecentlyUsedQueries.size()
+ ", maxSize=" + maxSize + ", ramBytesUsed=" + ramBytesUsed() + ", maxRamBytesUsed=" + maxRamBytesUsed);
}
for (LeafCache leafCache : cache.values()) {
Set<Query> keys = Collections.newSetFromMap(new IdentityHashMap<>());
keys.addAll(leafCache.cache.keySet());
keys.removeAll(mostRecentlyUsedQueries);
if (!keys.isEmpty()) {
throw new AssertionError("One leaf cache contains more keys than the top-level cache: " + keys);
void assertConsistent() {
lock.lock();
try {
if (requiresEviction()) {
throw new AssertionError("requires evictions: size=" + mostRecentlyUsedQueries.size()
+ ", maxSize=" + maxSize + ", ramBytesUsed=" + ramBytesUsed() + ", maxRamBytesUsed=" + maxRamBytesUsed);
}
}
long recomputedRamBytesUsed =
HASHTABLE_RAM_BYTES_PER_ENTRY * cache.size()
+ LINKED_HASHTABLE_RAM_BYTES_PER_ENTRY * uniqueQueries.size();
for (Query query : mostRecentlyUsedQueries) {
recomputedRamBytesUsed += ramBytesUsed(query);
}
for (LeafCache leafCache : cache.values()) {
recomputedRamBytesUsed += HASHTABLE_RAM_BYTES_PER_ENTRY * leafCache.cache.size();
for (DocIdSet set : leafCache.cache.values()) {
recomputedRamBytesUsed += set.ramBytesUsed();
for (LeafCache leafCache : cache.values()) {
Set<Query> keys = Collections.newSetFromMap(new IdentityHashMap<>());
keys.addAll(leafCache.cache.keySet());
keys.removeAll(mostRecentlyUsedQueries);
if (!keys.isEmpty()) {
throw new AssertionError("One leaf cache contains more keys than the top-level cache: " + keys);
}
}
long recomputedRamBytesUsed =
HASHTABLE_RAM_BYTES_PER_ENTRY * cache.size()
+ LINKED_HASHTABLE_RAM_BYTES_PER_ENTRY * uniqueQueries.size();
for (Query query : mostRecentlyUsedQueries) {
recomputedRamBytesUsed += ramBytesUsed(query);
}
for (LeafCache leafCache : cache.values()) {
recomputedRamBytesUsed += HASHTABLE_RAM_BYTES_PER_ENTRY * leafCache.cache.size();
for (DocIdSet set : leafCache.cache.values()) {
recomputedRamBytesUsed += set.ramBytesUsed();
}
}
if (recomputedRamBytesUsed != ramBytesUsed) {
throw new AssertionError("ramBytesUsed mismatch : " + ramBytesUsed + " != " + recomputedRamBytesUsed);
}
}
if (recomputedRamBytesUsed != ramBytesUsed) {
throw new AssertionError("ramBytesUsed mismatch : " + ramBytesUsed + " != " + recomputedRamBytesUsed);
}
long recomputedCacheSize = 0;
for (LeafCache leafCache : cache.values()) {
recomputedCacheSize += leafCache.cache.size();
}
if (recomputedCacheSize != getCacheSize()) {
throw new AssertionError("cacheSize mismatch : " + getCacheSize() + " != " + recomputedCacheSize);
long recomputedCacheSize = 0;
for (LeafCache leafCache : cache.values()) {
recomputedCacheSize += leafCache.cache.size();
}
if (recomputedCacheSize != getCacheSize()) {
throw new AssertionError("cacheSize mismatch : " + getCacheSize() + " != " + recomputedCacheSize);
}
} finally {
lock.unlock();
}
}
// pkg-private for testing
// return the list of cached queries in LRU order
synchronized List<Query> cachedQueries() {
return new ArrayList<>(mostRecentlyUsedQueries);
List<Query> cachedQueries() {
lock.lock();
try {
return new ArrayList<>(mostRecentlyUsedQueries);
} finally {
lock.unlock();
}
}
@Override
@ -438,8 +481,11 @@ public class LRUQueryCache implements QueryCache, Accountable {
@Override
public Collection<Accountable> getChildResources() {
synchronized (this) {
lock.lock();
try {
return Accountables.namedAccountables("segment", cache);
} finally {
lock.unlock();
}
}
@ -659,7 +705,18 @@ public class LRUQueryCache implements QueryCache, Accountable {
return in.scorer(context);
}
DocIdSet docIdSet = get(in.getQuery(), context);
// If the lock is already busy, prefer using the uncached version than waiting
if (lock.tryLock() == false) {
return in.scorer(context);
}
DocIdSet docIdSet;
try {
docIdSet = get(in.getQuery(), context);
} finally {
lock.unlock();
}
if (docIdSet == null) {
if (policy.shouldCache(in.getQuery())) {
docIdSet = cache(context);
@ -692,7 +749,18 @@ public class LRUQueryCache implements QueryCache, Accountable {
return in.bulkScorer(context);
}
DocIdSet docIdSet = get(in.getQuery(), context);
// If the lock is already busy, prefer using the uncached version than waiting
if (lock.tryLock() == false) {
return in.bulkScorer(context);
}
DocIdSet docIdSet;
try {
docIdSet = get(in.getQuery(), context);
} finally {
lock.unlock();
}
if (docIdSet == null) {
if (policy.shouldCache(in.getQuery())) {
docIdSet = cache(context);