Return allocated memory with malloc_trim when queue is empty

common/notificationconsumer.cpp

@@ -2,6 +2,7 @@
 
 #include <iostream>
 #include <deque>
+#include <malloc.h>
 #include "redisapi.h"
 
 #define NOTIFICATION_SUBSCRIBE_TIMEOUT (1000)
@@ -154,6 +155,27 @@ void swss::NotificationConsumer::pop(std::string &op, std::string &data, std::ve
     std::string msg = m_queue.front();
     m_queue.pop();
 
+    if (m_queue.empty())
+    {
+        /***
+         * If there is a burst of notifications that causes the queue to grow in size,
+         * memory allocated by the queue will not be released even after the all items 
+         * have been popped.
+         * 
+         * Force the memory to be released by destroying existing queue and creating a new one.
+         */
+        SWSS_LOG_DEBUG("%s queue is empty, calling malloc_trim()", m_channel.c_str());
+        int rv = malloc_trim(0);
+        if (rv == 1)
+        {
+            SWSS_LOG_DEBUG("Memory released successfully");
+        }
+        else
+        {
+            SWSS_LOG_DEBUG("No memory released by malloc_trim");
+        }
+    }
+
     values.clear();
     JSon::readJson(msg, values);