Fix race condition when adding two requests with same name

solr/core/src/java/org/apache/solr/handler/admin/CoreAdminHandler.java

@@ -536,7 +536,11 @@ public void submitAsyncTask(TaskObject taskObject) throws SolrException {
 
     private void addTask(TaskObject taskObject) {
       // Ensure task ID is not already in use
-      if (requestStatusCache.asMap().containsKey(taskObject.taskId)) {
+      TaskObject taskInCache = requestStatusCache.get(taskObject.taskId, n -> taskObject);
+
+      // If we get a different task instance, it means one was already in the cache with the
+      // same name. Just reject the new one.
+      if (taskInCache != taskObject) {
         throw new SolrException(
             ErrorCode.BAD_REQUEST, "Duplicate request with the same requestid found.");
       }

solr/core/src/test/org/apache/solr/handler/admin/CoreAdminHandlerTest.java

@@ -569,4 +569,26 @@ public void testTrackedRequestExpiration() throws Exception {
       asyncTracker.shutdown();
     }
   }
+
+  /** Check we reject a task is the async ID already exists. */
+  @Test
+  public void testDuplicatedRequestId() {
+
+    // Different tasks but with same ID
+    TaskObject task1 = new TaskObject("id1", "ACTION", false, null);
+    TaskObject task2 = new TaskObject("id1", "ACTION", false, null);
+
+    CoreAdminAsyncTracker asyncTracker = new CoreAdminAsyncTracker();
+    try {
+      asyncTracker.submitAsyncTask(task1);
+      try {
+        asyncTracker.submitAsyncTask(task2);
+        fail("Task should have been rejected.");
+      } catch (SolrException e) {
+        assertEquals("Duplicate request with the same requestid found.", e.getMessage());
+      }
+    } finally {
+      asyncTracker.shutdown();
+    }
+  }
 }