Fix unknown exception caused by thread safety issue

kafka-impl/src/main/java/io/streamnative/pulsar/handlers/kop/storage/ReplicaManager.java

@@ -108,17 +108,18 @@ private static class PendingProduceCallback implements Runnable {
         final CompletableFuture<Map<TopicPartition, ProduceResponse.PartitionResponse>> completableFuture;
         Map<TopicPartition, MemoryRecords> entriesPerPartition;
         @Override
-        public void run() {
+        public synchronized void run() {
             topicPartitionNum.set(0);
             if (completableFuture.isDone()) {
                 // It may be triggered again in DelayedProduceAndFetch
                 return;
             }
             // add the topicPartition with timeout error if it's not existed in responseMap
             entriesPerPartition.keySet().forEach(topicPartition -> {
-                if (!responseMap.containsKey(topicPartition)) {
+                ProduceResponse.PartitionResponse response = responseMap.putIfAbsent(topicPartition,
+                        new ProduceResponse.PartitionResponse(Errors.REQUEST_TIMED_OUT));
+                if (response == null) {
                     log.error("Adding dummy REQUEST_TIMED_OUT to produce response for {}", topicPartition);
-                    responseMap.put(topicPartition, new ProduceResponse.PartitionResponse(Errors.REQUEST_TIMED_OUT));
                 }
             });
             if (log.isDebugEnabled()) {