From 7f675d92313b2287aa4e6ef1ec3ce1ed67aff8d3 Mon Sep 17 00:00:00 2001
From: "copilot-swe-agent[bot]" <198982749+Copilot@users.noreply.github.com>
Date: Thu, 23 Apr 2026 17:23:41 +0000
Subject: [PATCH 1/2] Fix race condition in
 ReplicatedContext.getServletContext()

Agent-Logs-Url: https://github.com/markt-asf/tomcat/sessions/14161c12-b181-4367-a8d5-877b7e26f95e

Co-authored-by: markt-asf <4690029+markt-asf@users.noreply.github.com>
---
 .../ha/context/ReplicatedContext.java         | 10 +++-
 .../ha/context/TestReplicatedContext.java     | 57 +++++++++++++++++++
 webapps/docs/changelog.xml                    |  5 ++
 3 files changed, 69 insertions(+), 3 deletions(-)

diff --git a/java/org/apache/catalina/ha/context/ReplicatedContext.java b/java/org/apache/catalina/ha/context/ReplicatedContext.java
index 5ba2583fb0a0..8db3b70394cf 100644
--- a/java/org/apache/catalina/ha/context/ReplicatedContext.java
+++ b/java/org/apache/catalina/ha/context/ReplicatedContext.java
@@ -118,9 +118,13 @@ public ClassLoader[] getClassLoaders() {
     @Override
     public ServletContext getServletContext() {
         if (context == null) {
-            context = new ReplApplContext(this);
-            if (getAltDDName() != null) {
-                context.setAttribute(Globals.ALT_DD_ATTR, getAltDDName());
+            synchronized (this) {
+                if (context == null) {
+                    context = new ReplApplContext(this);
+                    if (getAltDDName() != null) {
+                        context.setAttribute(Globals.ALT_DD_ATTR, getAltDDName());
+                    }
+                }
             }
         }
 
diff --git a/test/org/apache/catalina/ha/context/TestReplicatedContext.java b/test/org/apache/catalina/ha/context/TestReplicatedContext.java
index 3840a19249cd..dffdab05dbf5 100644
--- a/test/org/apache/catalina/ha/context/TestReplicatedContext.java
+++ b/test/org/apache/catalina/ha/context/TestReplicatedContext.java
@@ -18,7 +18,12 @@
 
 import java.io.File;
 import java.io.IOException;
+import java.util.ArrayList;
+import java.util.List;
+import java.util.concurrent.CyclicBarrier;
+import java.util.concurrent.atomic.AtomicReference;
 
+import jakarta.servlet.ServletContext;
 import jakarta.servlet.ServletException;
 import jakarta.servlet.http.HttpServlet;
 import jakarta.servlet.http.HttpServletRequest;
@@ -37,6 +42,58 @@
 
 public class TestReplicatedContext extends TomcatBaseTest {
 
+    @Test
+    public void testGetServletContextReturnsSameInstanceUnderConcurrency() throws Exception {
+        Tomcat tomcat = getTomcatInstance();
+        Host host = tomcat.getHost();
+        if (host instanceof StandardHost) {
+            ((StandardHost) host).setContextClass(ReplicatedContext.class.getName());
+        }
+
+        File root = new File("test/webapp");
+        ReplicatedContext replicatedContext =
+                (ReplicatedContext) tomcat.addWebapp(host, "", root.getAbsolutePath());
+        tomcat.start();
+
+        // Null the context field to simulate the window during reload
+        replicatedContext.context = null;
+
+        int numThreads = 20;
+        CyclicBarrier barrier = new CyclicBarrier(numThreads);
+        List<Thread> threads = new ArrayList<>();
+        ServletContext[] results = new ServletContext[numThreads];
+        AtomicReference<Throwable> failure = new AtomicReference<>();
+
+        for (int i = 0; i < numThreads; i++) {
+            final int index = i;
+            Thread thread = new Thread(() -> {
+                try {
+                    barrier.await();
+                    results[index] = replicatedContext.getServletContext();
+                } catch (Throwable ex) {
+                    failure.set(ex);
+                }
+            });
+            thread.start();
+            threads.add(thread);
+        }
+
+        for (Thread thread : threads) {
+            thread.join(5000);
+        }
+
+        if (failure.get() != null) {
+            Assert.fail("Thread failed: " + failure.get());
+        }
+
+        ServletContext first = results[0];
+        Assert.assertNotNull(first);
+        for (int i = 1; i < numThreads; i++) {
+            Assert.assertSame(first, results[i]);
+        }
+    }
+
+
     @Test
     public void testBug57425() throws LifecycleException, IOException {
         Tomcat tomcat = getTomcatInstance();
diff --git a/webapps/docs/changelog.xml b/webapps/docs/changelog.xml
index 34f4bfd66f2b..8ef5bfae68dc 100644
--- a/webapps/docs/changelog.xml
+++ b/webapps/docs/changelog.xml
@@ -224,6 +224,11 @@
         ensure only one <code>ApplicationContext</code> instance is created.
         (dsoumis)
       </fix>
+      <fix>
+        Fix the same race condition in
+        <code>ReplicatedContext.getServletContext()</code> that was fixed in
+        <code>StandardContext.getServletContext()</code>. (dsoumis)
+      </fix>
     </changelog>
   </subsection>
   <subsection name="Coyote">

From a403b7a84214725e1bbfdb12b16816d86766ec79 Mon Sep 17 00:00:00 2001
From: "copilot-swe-agent[bot]" <198982749+Copilot@users.noreply.github.com>
Date: Thu, 23 Apr 2026 17:24:34 +0000
Subject: [PATCH 2/2] Remove changelog entry for ReplicatedContext fix

Agent-Logs-Url: https://github.com/markt-asf/tomcat/sessions/14161c12-b181-4367-a8d5-877b7e26f95e

Co-authored-by: markt-asf <4690029+markt-asf@users.noreply.github.com>
---
 webapps/docs/changelog.xml | 5 -----
 1 file changed, 5 deletions(-)

diff --git a/webapps/docs/changelog.xml b/webapps/docs/changelog.xml
index 8ef5bfae68dc..34f4bfd66f2b 100644
--- a/webapps/docs/changelog.xml
+++ b/webapps/docs/changelog.xml
@@ -224,11 +224,6 @@
         ensure only one <code>ApplicationContext</code> instance is created.
         (dsoumis)
       </fix>
-      <fix>
-        Fix the same race condition in
-        <code>ReplicatedContext.getServletContext()</code> that was fixed in
-        <code>StandardContext.getServletContext()</code>. (dsoumis)
-      </fix>
     </changelog>
   </subsection>
   <subsection name="Coyote">