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The following commit(s) were added to refs/heads/master by this push:
new db8fe9c24 ZOOKEEPER-4919: Make ResponseCache a LRU as it supposed to be
db8fe9c24 is described below
commit db8fe9c241942e2222271acc8bbb9321c7a4957d
Author: mikkosc <[email protected]>
AuthorDate: Sat Apr 19 19:58:31 2025 +0300
ZOOKEEPER-4919: Make ResponseCache a LRU as it supposed to be
Reviewers: tisonkun, kezhuw
Author: mikkosc
Closes #2243 from mikkosc/fix-lru-cache
---
.../org/apache/zookeeper/server/ResponseCache.java | 18 ++++++++--------
.../{ => quorum}/FollowerRequestProcessorTest.java | 0
.../apache/zookeeper/test/ResponseCacheTest.java | 24 ++++++++++++++++++++--
3 files changed, 32 insertions(+), 10 deletions(-)
diff --git
a/zookeeper-server/src/main/java/org/apache/zookeeper/server/ResponseCache.java
b/zookeeper-server/src/main/java/org/apache/zookeeper/server/ResponseCache.java
index 5c74caa12..4a1f87d49 100644
---
a/zookeeper-server/src/main/java/org/apache/zookeeper/server/ResponseCache.java
+++
b/zookeeper-server/src/main/java/org/apache/zookeeper/server/ResponseCache.java
@@ -33,8 +33,13 @@ public class ResponseCache {
public static final int DEFAULT_RESPONSE_CACHE_SIZE = 400;
private final int cacheSize;
private static class Entry {
- public Stat stat;
- public byte[] data;
+ public final Stat stat;
+ public final byte[] data;
+
+ Entry(Stat stat, byte[] data) {
+ this.stat = stat;
+ this.data = data;
+ }
}
private final Map<String, Entry> cache;
@@ -50,10 +55,7 @@ public int getCacheSize() {
}
public void put(String path, byte[] data, Stat stat) {
- Entry entry = new Entry();
- entry.data = data;
- entry.stat = stat;
- cache.put(path, entry);
+ cache.put(path, new Entry(stat, data));
}
public byte[] get(String key, Stat stat) {
@@ -76,10 +78,10 @@ public boolean isEnabled() {
private static class LRUCache<K, V> extends LinkedHashMap<K, V> {
- private int cacheSize;
+ private final int cacheSize;
LRUCache(int cacheSize) {
- super(cacheSize / 4);
+ super(cacheSize / 4, 0.75f, true);
this.cacheSize = cacheSize;
}
diff --git
a/zookeeper-server/src/test/java/org/apache/zookeeper/server/FollowerRequestProcessorTest.java
b/zookeeper-server/src/test/java/org/apache/zookeeper/server/quorum/FollowerRequestProcessorTest.java
similarity index 100%
rename from
zookeeper-server/src/test/java/org/apache/zookeeper/server/FollowerRequestProcessorTest.java
rename to
zookeeper-server/src/test/java/org/apache/zookeeper/server/quorum/FollowerRequestProcessorTest.java
diff --git
a/zookeeper-server/src/test/java/org/apache/zookeeper/test/ResponseCacheTest.java
b/zookeeper-server/src/test/java/org/apache/zookeeper/test/ResponseCacheTest.java
index 4b1639405..32af00ae8 100644
---
a/zookeeper-server/src/test/java/org/apache/zookeeper/test/ResponseCacheTest.java
+++
b/zookeeper-server/src/test/java/org/apache/zookeeper/test/ResponseCacheTest.java
@@ -79,6 +79,7 @@ public void performCacheTest(ZooKeeper zk, String path,
boolean useCache) throws
Stat writeStat = new Stat();
Stat readStat = new Stat();
byte[] readData = null;
+ int cacheSize =
Integer.getInteger(ZooKeeperServer.GET_DATA_RESPONSE_CACHE_SIZE);
int reads = 10;
long expectedHits = 0;
long expectedMisses = 0;
@@ -88,7 +89,7 @@ public void performCacheTest(ZooKeeper zk, String path,
boolean useCache) throws
LOG.info("caching: {}", useCache);
if (useCache) {
- assertEquals(zks.getReadResponseCache().getCacheSize(), 32);
+ assertEquals(zks.getReadResponseCache().getCacheSize(), cacheSize);
assertEquals(zks.getGetChildrenResponseCache().getCacheSize(), 64);
}
@@ -146,15 +147,21 @@ public void performCacheTest(ZooKeeper zk, String path,
boolean useCache) throws
createPath(path + "/a/b/e/g", zk);
createPath(path + "/a/b/e/h", zk);
+ createPath(path + "/x", zk);
+ for (int i = 0; i < cacheSize * 2; ++i) {
+ createPath(path + "/x/y" + i, zk);
+ }
+
checkPath(path + "/a", zk, 2);
checkPath(path + "/a/b", zk, 2);
checkPath(path + "/a/c", zk, 0);
checkPath(path + "/a/b/d", zk, 0);
checkPath(path + "/a/b/e", zk, 3);
checkPath(path + "/a/b/e/h", zk, 0);
+ checkPath(path + "/x", zk, cacheSize * 2);
if (useCache) {
- expectedMisses += 6;
+ expectedMisses += 7;
}
checkCacheStatus(expectedHits, expectedMisses,
"response_packet_get_children_cache_hits",
@@ -170,6 +177,19 @@ public void performCacheTest(ZooKeeper zk, String path,
boolean useCache) throws
checkCacheStatus(expectedHits, expectedMisses,
"response_packet_get_children_cache_hits",
"response_packet_get_children_cache_misses");
+
+ for (int i = 0; i < cacheSize * 2; ++i) {
+ checkPath(path + "/a", zk, 2);
+ checkPath(path + "/x/y" + i, zk, 0);
+
+ if (useCache) {
+ expectedHits += 1;
+ expectedMisses += 1;
+ }
+
+ checkCacheStatus(expectedHits, expectedMisses,
"response_packet_get_children_cache_hits",
+ "response_packet_get_children_cache_misses");
+ }
}
private void createPath(String path, ZooKeeper zk) throws Exception {
