From c44be3b0dd23c2543a65d00bd24e1ef316c0d6a2 Mon Sep 17 00:00:00 2001
From: Colm O hEigeartaigh <coheigea@apache.org>
Date: Tue, 10 Mar 2020 16:12:59 +0000
Subject: [PATCH] AMQ-7440 - Fix potential race condition in
 DiscoveryRegistryServlet

---
 .../transport/discovery/http/DiscoveryRegistryServlet.java | 7 +------
 1 file changed, 1 insertion(+), 6 deletions(-)

diff --git a/activemq-http/src/main/java/org/apache/activemq/transport/discovery/http/DiscoveryRegistryServlet.java b/activemq-http/src/main/java/org/apache/activemq/transport/discovery/http/DiscoveryRegistryServlet.java
index 9b519d04b7..ebfb7ae786 100644
--- a/activemq-http/src/main/java/org/apache/activemq/transport/discovery/http/DiscoveryRegistryServlet.java
+++ b/activemq-http/src/main/java/org/apache/activemq/transport/discovery/http/DiscoveryRegistryServlet.java
@@ -49,12 +49,7 @@ public class DiscoveryRegistryServlet extends HttpServlet {
     }
 
     private ConcurrentMap<String, Long> getServiceGroup(String group) {
-        ConcurrentMap<String, Long> rc = serviceGroups.get(group);
-        if( rc == null ) {
-            rc = new ConcurrentHashMap<String, Long>();
-            serviceGroups.put(group, rc);
-        }
-        return rc;
+        return serviceGroups.computeIfAbsent(group, k -> new ConcurrentHashMap<String, Long>());
     }
 
     @Override