[enh][broker] Add metrics for entry cache insertion, eviction (#17248)

Fixes #16584 ### Motivation With the `RangeCache`, it is hard to reason about its behavior other than cache hits/misses or the cache's size hitting the limit and triggering a size based eviction. This PR adds 3 new metrics to help provide additional insight into the cache's behavior. It adds `pulsar_ml_cache_inserted_entries_total`, `pulsar_ml_cache_evicted_entries_total`, and `pulsar_ml_cache_entries`. ### Modifications * Add new metrics for cache insertion, eviction, and current number of entries. * Add new methods to the `ManagedLedgerFactoryMXBean` interface. * Update several method return values in the `RangeCache`. * Update tests. ### Verifying this change This change is covered by modified tests that already existed. ### Does this pull request potentially affect one of the following parts: There is a breaking change to the `RangeCache` class for the `clear` and the `evictLEntriesBeforeTimestamp` methods. The previous result was a `long`, and now it is a `Pair<Integer, Long>`. The new result matches the same style as `evictLeastAccessedEntries`. Given that this class is only meant for use within the broker, I think it is reasonable to break these methods. I will send a note to the mailing list. ### Documentation - [x] `doc`
apache · Oct 13, 2022 · df33f59 · df33f59
1 parent 44d45af
commit df33f59
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diff --git a/managed-ledger/src/main/java/org/apache/bookkeeper/mledger/ManagedLedgerFactoryMXBean.java b/managed-ledger/src/main/java/org/apache/bookkeeper/mledger/ManagedLedgerFactoryMXBean.java
@@ -66,4 +66,19 @@ public interface ManagedLedgerFactoryMXBean {
      * Get the number of cache evictions during the last minute.
      */
     long getNumberOfCacheEvictions();
+
+    /**
+     * Cumulative number of entries inserted into the cache.
+     */
+    long getCacheInsertedEntriesCount();
+
+    /**
+     * Cumulative number of entries evicted from the cache.
+     */
+    long getCacheEvictedEntriesCount();
+
+    /**
+     * Current number of entries in the cache.
+     */
+    long getCacheEntriesCount();
 }
diff --git a/...edger/src/main/java/org/apache/bookkeeper/mledger/impl/ManagedLedgerFactoryMBeanImpl.java b/...edger/src/main/java/org/apache/bookkeeper/mledger/impl/ManagedLedgerFactoryMBeanImpl.java
@@ -19,6 +19,7 @@
 package org.apache.bookkeeper.mledger.impl;
 
 import java.util.concurrent.TimeUnit;
+import java.util.concurrent.atomic.LongAdder;
 import org.apache.bookkeeper.mledger.ManagedLedgerFactoryMXBean;
 import org.apache.pulsar.common.stats.Rate;
 
@@ -31,6 +32,10 @@ public class ManagedLedgerFactoryMBeanImpl implements ManagedLedgerFactoryMXBean
     final Rate cacheMisses = new Rate();
     final Rate cacheEvictions = new Rate();
 
+    private final LongAdder insertedEntryCount = new LongAdder();
+    private final LongAdder evictedEntryCount = new LongAdder();
+    private final LongAdder cacheEntryCount = new LongAdder();
+
     public ManagedLedgerFactoryMBeanImpl(ManagedLedgerFactoryImpl factory) throws Exception {
         this.factory = factory;
     }
@@ -64,6 +69,16 @@ public void recordCacheEviction() {
         cacheEvictions.recordEvent();
     }
 
+    public void recordCacheInsertion() {
+        insertedEntryCount.increment();
+        cacheEntryCount.increment();
+    }
+
+    public void recordNumberOfCacheEntriesEvicted(int count) {
+        evictedEntryCount.add(count);
+        cacheEntryCount.add(-count);
+    }
+
     @Override
     public int getNumberOfManagedLedgers() {
         return factory.ledgers.size();
@@ -104,4 +119,16 @@ public long getNumberOfCacheEvictions() {
         return cacheEvictions.getCount();
     }
 
+    public long getCacheInsertedEntriesCount() {
+        return insertedEntryCount.sum();
+    }
+
+    public long getCacheEvictedEntriesCount() {
+        return evictedEntryCount.sum();
+    }
+
+    public long getCacheEntriesCount() {
+        return cacheEntryCount.sum();
+    }
+
 }
diff --git a/...ed-ledger/src/main/java/org/apache/bookkeeper/mledger/impl/cache/RangeEntryCacheImpl.java b/...ed-ledger/src/main/java/org/apache/bookkeeper/mledger/impl/cache/RangeEntryCacheImpl.java
@@ -168,7 +168,7 @@ public void invalidateEntries(final PositionImpl lastPosition) {
                     lastPosition, entriesRemoved, sizeRemoved);
         }
 
-        manager.entriesRemoved(sizeRemoved);
+        manager.entriesRemoved(sizeRemoved, entriesRemoved);
     }
 
     @Override
@@ -184,7 +184,7 @@ public void invalidateAllEntries(long ledgerId) {
                     ml.getName(), ledgerId, entriesRemoved, sizeRemoved);
         }
 
-        manager.entriesRemoved(sizeRemoved);
+        manager.entriesRemoved(sizeRemoved, entriesRemoved);
     }
 
     @Override
@@ -338,8 +338,8 @@ private void asyncReadEntry0(ReadHandle lh, long firstEntry, long lastEntry, boo
 
     @Override
     public void clear() {
-        long removedSize = entries.clear();
-        manager.entriesRemoved(removedSize);
+        Pair<Integer, Long> removedPair = entries.clear();
+        manager.entriesRemoved(removedPair.getRight(), removedPair.getLeft());
     }
 
     @Override
@@ -364,14 +364,14 @@ public Pair<Integer, Long> evictEntries(long sizeToFree) {
                             + " -- Current Size: {} Mb",
                     ml.getName(), sizeToFree / MB, evictedEntries, evictedSize / MB, entries.getSize() / MB);
         }
-        manager.entriesRemoved(evictedSize);
+        manager.entriesRemoved(evictedSize, evictedEntries);
         return evicted;
     }
 
     @Override
     public void invalidateEntriesBeforeTimestamp(long timestamp) {
-        long evictedSize = entries.evictLEntriesBeforeTimestamp(timestamp);
-        manager.entriesRemoved(evictedSize);
+        Pair<Integer, Long> evictedPair = entries.evictLEntriesBeforeTimestamp(timestamp);
+        manager.entriesRemoved(evictedPair.getRight(), evictedPair.getLeft());
     }
 
     private static final Logger log = LoggerFactory.getLogger(RangeEntryCacheImpl.class);

diff --git a/...er/src/main/java/org/apache/bookkeeper/mledger/impl/cache/RangeEntryCacheManagerImpl.java b/...er/src/main/java/org/apache/bookkeeper/mledger/impl/cache/RangeEntryCacheManagerImpl.java
@@ -141,10 +141,12 @@ boolean hasSpaceInCache() {
     }
 
     void entryAdded(long size) {
+        mlFactoryMBean.recordCacheInsertion();
         currentSize.addAndGet(size);
     }
 
-    void entriesRemoved(long size) {
+    void entriesRemoved(long size, int count) {
+        mlFactoryMBean.recordNumberOfCacheEntriesEvicted(count);
         currentSize.addAndGet(-size);
     }
 

diff --git a/managed-ledger/src/main/java/org/apache/bookkeeper/mledger/util/RangeCache.java b/managed-ledger/src/main/java/org/apache/bookkeeper/mledger/util/RangeCache.java
@@ -187,8 +187,9 @@ public Pair<Integer, Long> evictLeastAccessedEntries(long minSize) {
     * @param maxTimestamp the max timestamp of the entries to be evicted
     * @return the tota
     */
-   public long evictLEntriesBeforeTimestamp(long maxTimestamp) {
+   public Pair<Integer, Long> evictLEntriesBeforeTimestamp(long maxTimestamp) {
        long removedSize = 0;
+       int removedCount = 0;
 
        while (true) {
            Map.Entry<Key, Value> entry = entries.firstEntry();
@@ -203,11 +204,12 @@ public long evictLEntriesBeforeTimestamp(long maxTimestamp) {
 
            Value value = entry.getValue();
            removedSize += weighter.getSize(value);
+           removedCount++;
            value.release();
        }
 
        size.addAndGet(-removedSize);
-       return removedSize;
+       return Pair.of(removedCount, removedSize);
    }
 
     /**
@@ -226,8 +228,9 @@ public long getSize() {
      *
      * @return size of removed entries
      */
-    public synchronized long clear() {
+    public synchronized Pair<Integer, Long> clear() {
         long removedSize = 0;
+        int removedCount = 0;
 
         while (true) {
             Map.Entry<Key, Value> entry = entries.pollFirstEntry();
@@ -236,12 +239,13 @@ public synchronized long clear() {
             }
             Value value = entry.getValue();
             removedSize += weighter.getSize(value);
+            removedCount++;
             value.release();
         }
 
         entries.clear();
         size.getAndAdd(-removedSize);
-        return removedSize;
+        return Pair.of(removedCount, removedSize);
     }
 
     /**

diff --git a/managed-ledger/src/test/java/org/apache/bookkeeper/mledger/impl/EntryCacheManagerTest.java b/managed-ledger/src/test/java/org/apache/bookkeeper/mledger/impl/EntryCacheManagerTest.java
@@ -94,6 +94,9 @@ public void simple() throws Exception {
         assertEquals(factory2.getMbean().getCacheMissesRate(), 0.0);
         assertEquals(factory2.getMbean().getCacheHitsThroughput(), 0.0);
         assertEquals(factory2.getMbean().getNumberOfCacheEvictions(), 0);
+        assertEquals(factory2.getMbean().getCacheInsertedEntriesCount(), 2);
+        assertEquals(factory2.getMbean().getCacheEvictedEntriesCount(), 0);
+        assertEquals(factory2.getMbean().getCacheEntriesCount(), 2);
 
         cache2.insert(EntryImpl.create(2, 0, new byte[1]));
         cache2.insert(EntryImpl.create(2, 1, new byte[1]));
@@ -129,6 +132,9 @@ public void simple() throws Exception {
         assertEquals(factory2.getMbean().getCacheMissesRate(), 0.0);
         assertEquals(factory2.getMbean().getCacheHitsThroughput(), 0.0);
         assertEquals(factory2.getMbean().getNumberOfCacheEvictions(), 1);
+        assertEquals(factory2.getMbean().getCacheInsertedEntriesCount(), 5);
+        assertEquals(factory2.getMbean().getCacheEntriesCount(), 2);
+        assertEquals(factory2.getMbean().getCacheEvictedEntriesCount(), 3);
     }
 
     @Test
@@ -153,6 +159,9 @@ public void doubleInsert() throws Exception {
 
         assertEquals(cache1.getSize(), 7);
         assertEquals(cacheManager.getSize(), 7);
+        assertEquals(factory2.getMbean().getCacheInsertedEntriesCount(), 2);
+        assertEquals(factory2.getMbean().getCacheEntriesCount(), 2);
+        assertEquals(factory2.getMbean().getCacheEvictedEntriesCount(), 0);
     }
 
     @Test
@@ -185,6 +194,9 @@ public void cacheSizeUpdate() throws Exception {
 
         cacheManager.removeEntryCache(ml1.getName());
         assertTrue(cacheManager.getSize() > 0);
+        assertEquals(factory2.getMbean().getCacheInsertedEntriesCount(), 20);
+        assertEquals(factory2.getMbean().getCacheEntriesCount(), 0);
+        assertEquals(factory2.getMbean().getCacheEvictedEntriesCount(), 20);
     }
 
 
@@ -217,6 +229,9 @@ public void cacheDisabled() throws Exception {
         assertEquals(factory2.getMbean().getCacheMissesRate(), 0.0);
         assertEquals(factory2.getMbean().getCacheHitsThroughput(), 0.0);
         assertEquals(factory2.getMbean().getNumberOfCacheEvictions(), 0);
+        assertEquals(factory2.getMbean().getCacheInsertedEntriesCount(), 0);
+        assertEquals(factory2.getMbean().getCacheEntriesCount(), 0);
+        assertEquals(factory2.getMbean().getCacheEvictedEntriesCount(), 0);
 
         cache2.insert(EntryImpl.create(2, 0, new byte[1]));
         cache2.insert(EntryImpl.create(2, 1, new byte[1]));
@@ -253,6 +268,9 @@ public void verifyNoCacheIfNoConsumer() throws Exception {
         assertEquals(factory2.getMbean().getCacheMissesRate(), 0.0);
         assertEquals(factory2.getMbean().getCacheHitsThroughput(), 0.0);
         assertEquals(factory2.getMbean().getNumberOfCacheEvictions(), 0);
+        assertEquals(factory2.getMbean().getCacheInsertedEntriesCount(), 0);
+        assertEquals(factory2.getMbean().getCacheEntriesCount(), 0);
+        assertEquals(factory2.getMbean().getCacheEvictedEntriesCount(), 0);
     }
 
     @Test

diff --git a/managed-ledger/src/test/java/org/apache/bookkeeper/mledger/util/RangeCacheTest.java b/managed-ledger/src/test/java/org/apache/bookkeeper/mledger/util/RangeCacheTest.java
@@ -139,8 +139,9 @@ public void customTimeExtraction() {
         assertEquals(cache.getSize(), 10);
         assertEquals(cache.getNumberOfEntries(), 4);
 
-        long evictedSize = cache.evictLEntriesBeforeTimestamp(3);
-        assertEquals(evictedSize, 6);
+        Pair<Integer, Long> evictedSize = cache.evictLEntriesBeforeTimestamp(3);
+        assertEquals(evictedSize.getRight().longValue(), 6);
+        assertEquals(evictedSize.getLeft().longValue(), 3);
 
         assertEquals(cache.getSize(), 4);
         assertEquals(cache.getNumberOfEntries(), 1);

diff --git a/...roker/src/main/java/org/apache/pulsar/broker/stats/metrics/ManagedLedgerCacheMetrics.java b/...roker/src/main/java/org/apache/pulsar/broker/stats/metrics/ManagedLedgerCacheMetrics.java
@@ -48,6 +48,9 @@ public synchronized List<Metrics> generate() {
 
         m.put("brk_ml_count", mlCacheStats.getNumberOfManagedLedgers());
         m.put("brk_ml_cache_used_size", mlCacheStats.getCacheUsedSize());
+        m.put("brk_ml_cache_inserted_entries_total", mlCacheStats.getCacheInsertedEntriesCount());
+        m.put("brk_ml_cache_evicted_entries_total", mlCacheStats.getCacheEvictedEntriesCount());
+        m.put("brk_ml_cache_entries", mlCacheStats.getCacheEntriesCount());
         m.put("brk_ml_cache_evictions", mlCacheStats.getNumberOfCacheEvictions());
         m.put("brk_ml_cache_hits_rate", mlCacheStats.getCacheHitsRate());
         m.put("brk_ml_cache_misses_rate", mlCacheStats.getCacheMissesRate());

diff --git a/site2/docs/reference-metrics.md b/site2/docs/reference-metrics.md
@@ -159,6 +159,9 @@ All the broker metrics are labelled with the following labels:
 | Name | Type   | Description                                          |
 |---|---|---|
 | pulsar_ml_cache_evictions | Gauge  | The number of cache evictions during the last minute. |
+| pulsar_ml_cache_inserted_entries_total | Counter | The number of entries inserted into the entry cache. |
+| pulsar_ml_cache_evicted_entries_total | Counter | The number of entries evicted from the entry cache. |
+| pulsar_ml_cache_entries | Gauge | The number of entries in the entry cache. |
 | pulsar_ml_cache_hits_rate | Gauge  | The number of cache hits per second on the broker side. |
 | pulsar_ml_cache_hits_throughput | Gauge  | The amount of data (byte per second) retrieved from the cache on the broker side. |
 | pulsar_ml_cache_misses_rate | Gauge  | The number of cache missed per second on the broker side. |