diff --git a/oak-segment-tar/src/main/java/org/apache/jackrabbit/oak/segment/spi/persistence/persistentcache/AbstractPersistentCache.java b/oak-segment-tar/src/main/java/org/apache/jackrabbit/oak/segment/spi/persistence/persistentcache/AbstractPersistentCache.java
index 4c467f9c25..412e82e153 100644
--- a/oak-segment-tar/src/main/java/org/apache/jackrabbit/oak/segment/spi/persistence/persistentcache/AbstractPersistentCache.java
+++ b/oak-segment-tar/src/main/java/org/apache/jackrabbit/oak/segment/spi/persistence/persistentcache/AbstractPersistentCache.java
@@ -30,8 +30,10 @@ import org.slf4j.LoggerFactory;
 
 import java.io.Closeable;
 import java.util.HashSet;
+import java.util.Set;
 import java.util.UUID;
 import java.util.concurrent.Callable;
+import java.util.concurrent.ConcurrentHashMap;
 import java.util.concurrent.ExecutorService;
 import java.util.concurrent.Executors;
 import java.util.concurrent.TimeUnit;
@@ -45,13 +47,13 @@ public abstract class AbstractPersistentCache implements PersistentCache, Closea
     protected ExecutorService executor;
     protected AtomicLong cacheSize = new AtomicLong(0);
     protected PersistentCache nextCache;
-    protected final HashSet<String> writesPending;
+    protected final Set<String> writesPending;
 
     protected SegmentCacheStats segmentCacheStats;
 
     public AbstractPersistentCache() {
         executor = Executors.newFixedThreadPool(THREADS);
-        writesPending = new HashSet<>();
+        writesPending = ConcurrentHashMap.newKeySet();
     }
 
     public PersistentCache linkWith(AbstractPersistentCache nextCache) {
@@ -139,20 +141,14 @@ public abstract class AbstractPersistentCache implements PersistentCache, Closea
     }
 
     public int getWritesPending() {
-        synchronized (writesPending) {
         return writesPending.size();
     }
-    }
 
     protected boolean lockSegmentWrite(String segmentId) {
-        synchronized (writesPending) {
         return writesPending.add(segmentId);
     }
-    }
 
     protected void unlockSegmentWrite(String segmentId) {
-        synchronized (writesPending) {
         writesPending.remove(segmentId);
     }
 }
-}