Skip replication processing when no replication domain is configured

The Multimaster Synchronization provider is enabled by default even on
standalone servers with no replication domain configured, and its three
per-operation hooks (conflict resolution, pre-operation, post-operation)
each called findDomain(), which iterated the request controls and walked
the entry DN up to the suffix querying an empty domains map, allocating
a fresh result object every time.

Return null from findDomain() before the DN walk when no domains are
registered (repair-control processing is preserved), and reuse a shared
stateless ContinueProcessing result instead of allocating one per hook
invocation.

An interleaved A/B under concurrent modify load shows no measurable
throughput change on an 8-core host — the write path is dominated by
the JE write-ahead log — so this is a cleanliness fix: it removes
pointless per-write work from every non-replicated deployment rather
than a measured win.

Author: vharseko

opendj-server-legacy/src/main/java/org/opends/server/replication/plugin/MultimasterReplication.java

@@ -13,6 +13,7 @@
  *
  * Copyright 2006-2010 Sun Microsystems, Inc.
  * Portions Copyright 2011-2016 ForgeRock AS.
+ * Portions Copyright 2026 3A Systems, LLC
  */
 package org.opends.server.replication.plugin;
 
@@ -97,6 +98,12 @@ public class MultimasterReplication
 
   private ReplicationServerListener replicationServerListener;
   private static final Map<DN, LDAPReplicationDomain> domains = new ConcurrentHashMap<>(4);
+  /**
+   * Shared stateless "continue processing" result: the provider hooks run for
+   * every operation, so avoid allocating a fresh result each time.
+   */
+  private static final SynchronizationProviderResult CONTINUE =
+      new SynchronizationProviderResult.ContinueProcessing();
   private static final DSRSShutdownSync dsrsShutdownSync = new DSRSShutdownSync();
   /** The queue of received update messages, to be treated by the ReplayThread threads. */
   private static final BlockingQueue<UpdateToReplay> updateToReplayQueue = new LinkedBlockingQueue<>(10000);
@@ -166,6 +173,15 @@ public static LDAPReplicationDomain findDomain(DN dn, PluginOperation pluginOp)
         }
     }
 
+    if (domains.isEmpty())
+    {
+      // The Multimaster Synchronization provider is enabled by default even
+      // on standalone servers with no replication domain configured: skip
+      // the walk to the suffix that every write operation would otherwise
+      // pay three times (conflict resolution, pre- and post-operation).
+      return null;
+    }
+
     LDAPReplicationDomain domain = null;
     DN temp = dn;
     BackendConfigManager backendConfigManager =
@@ -402,7 +418,7 @@ public SynchronizationProviderResult handleConflictResolution(
     {
       return domain.handleConflictResolution(modifyOperation);
     }
-    return new SynchronizationProviderResult.ContinueProcessing();
+    return CONTINUE;
   }
 
   @Override
@@ -414,7 +430,7 @@ public SynchronizationProviderResult handleConflictResolution(
     {
       return domain.handleConflictResolution(addOperation);
     }
-    return new SynchronizationProviderResult.ContinueProcessing();
+    return CONTINUE;
   }
 
   @Override
@@ -426,7 +442,7 @@ public SynchronizationProviderResult handleConflictResolution(
     {
       return domain.handleConflictResolution(deleteOperation);
     }
-    return new SynchronizationProviderResult.ContinueProcessing();
+    return CONTINUE;
   }
 
   @Override
@@ -438,7 +454,7 @@ public SynchronizationProviderResult handleConflictResolution(
     {
       return domain.handleConflictResolution(modifyDNOperation);
     }
-    return new SynchronizationProviderResult.ContinueProcessing();
+    return CONTINUE;
   }
 
   @Override
@@ -450,7 +466,7 @@ public SynchronizationProviderResult handleConflictResolution(
 
     if (domain == null || !domain.solveConflict())
     {
-      return new SynchronizationProviderResult.ContinueProcessing();
+      return CONTINUE;
     }
 
     EntryHistorical historicalInformation = (EntryHistorical)
@@ -475,14 +491,14 @@ public SynchronizationProviderResult handleConflictResolution(
           ResultCode.SUCCESS, null);
     }
 
-    return new SynchronizationProviderResult.ContinueProcessing();
+    return CONTINUE;
   }
 
   @Override
   public SynchronizationProviderResult doPreOperation(
          PreOperationDeleteOperation deleteOperation) throws DirectoryException
   {
-    return new SynchronizationProviderResult.ContinueProcessing();
+    return CONTINUE;
   }
 
   @Override
@@ -495,7 +511,7 @@ public SynchronizationProviderResult doPreOperation(
 
     if (domain == null || !domain.solveConflict())
     {
-      return new SynchronizationProviderResult.ContinueProcessing();
+      return CONTINUE;
     }
 
     // The historical object is retrieved from the attachment created
@@ -516,7 +532,7 @@ public SynchronizationProviderResult doPreOperation(
     // Add to the operation the historical attribute : "dn:changeNumber:moddn"
     historicalInformation.setHistoricalAttrToOperation(modifyDNOperation);
 
-    return new SynchronizationProviderResult.ContinueProcessing();
+    return CONTINUE;
   }
 
   @Override
@@ -528,7 +544,7 @@ public SynchronizationProviderResult doPreOperation(
       findDomain(addOperation.getEntryDN(), addOperation);
     if (domain == null)
     {
-      return new SynchronizationProviderResult.ContinueProcessing();
+      return CONTINUE;
     }
 
     // For LOCAL op only, generate CSN and attach Context
@@ -540,7 +556,7 @@ public SynchronizationProviderResult doPreOperation(
     // Add to the operation the historical attribute : "dn:changeNumber:add"
     EntryHistorical.setHistoricalAttrToOperation(addOperation);
 
-    return new SynchronizationProviderResult.ContinueProcessing();
+    return CONTINUE;
   }
 
   @Override