diff --git a/polaris-service/src/main/java/org/apache/polaris/service/config/RealmEntityManagerFactory.java b/polaris-service/src/main/java/org/apache/polaris/service/config/RealmEntityManagerFactory.java
index b5fb48a7e..b896a13eb 100644
--- a/polaris-service/src/main/java/org/apache/polaris/service/config/RealmEntityManagerFactory.java
+++ b/polaris-service/src/main/java/org/apache/polaris/service/config/RealmEntityManagerFactory.java
@@ -18,8 +18,8 @@
  */
 package org.apache.polaris.service.config;
 
-import java.util.HashMap;
 import java.util.Map;
+import java.util.concurrent.ConcurrentHashMap;
 import org.apache.polaris.core.context.RealmContext;
 import org.apache.polaris.core.persistence.MetaStoreManagerFactory;
 import org.apache.polaris.core.persistence.PolarisEntityManager;
@@ -32,7 +32,7 @@ public class RealmEntityManagerFactory {
   private final MetaStoreManagerFactory metaStoreManagerFactory;
 
   // Key: realmIdentifier
-  private final Map<String, PolarisEntityManager> cachedEntityManagers = new HashMap<>();
+  private final Map<String, PolarisEntityManager> cachedEntityManagers = new ConcurrentHashMap<>();
 
   // Subclasses for test injection.
   protected RealmEntityManagerFactory() {
@@ -47,17 +47,14 @@ public PolarisEntityManager getOrCreateEntityManager(RealmContext context) {
     String realm = context.getRealmIdentifier();
 
     LOGGER.debug("Looking up PolarisEntityManager for realm {}", realm);
-    PolarisEntityManager entityManagerInstance = cachedEntityManagers.get(realm);
-    if (entityManagerInstance == null) {
-      LOGGER.info("Initializing new PolarisEntityManager for realm {}", realm);
 
-      entityManagerInstance =
-          new PolarisEntityManager(
+    return cachedEntityManagers.computeIfAbsent(
+        realm,
+        r -> {
+          LOGGER.info("Initializing new PolarisEntityManager for realm {}", r);
+          return new PolarisEntityManager(
               metaStoreManagerFactory.getOrCreateMetaStoreManager(context),
               metaStoreManagerFactory.getOrCreateStorageCredentialCache(context));
-
-      cachedEntityManagers.put(realm, entityManagerInstance);
-    }
-    return entityManagerInstance;
+        });
   }
 }