Eliminate unnecessary memory allocation in extended query protocol.

When pending messages are created, Pgpool-II did like:

(1) pmsg = pool_pending_message_create();	/* create a pending message */
(2) pool_pending_message_dest_set(pmsg, query_context)	/* set PostgreSQL node ids to be sent */
(3) pool_pending_message_query_set(pmsg, query_context);	/* add query context */
(4) pool_pending_message_add(pmsg);		/* add the pending message to the list */
(5) pool_pending_message_free_pending_message(pmsg);	/* free memory allocated by pool_pending_message_create();

The reason why pool_pending_message_free_pending_message(pmsg) is
called here is, pool_pending_message_add() creates a copy of the
pending message then add it to the list. This commit modifies
pool_pending_message_add() so that it does not create a copy of the
object and adds it to the pending messages list. This way, we can
eliminate (5) as well and it should reduce memory footprint and CPU
cycle.

diff --git a/src/context/pool_session_context.c b/src/context/pool_session_context.c
index 7082771914ac65f400888b8586a86d1baa694c95..f25d501dfa3ae73d0493bebb1c1dd690ab8b8a80 100644 (file)
--- a/src/context/pool_session_context.c
+++ b/src/context/pool_session_context.c
@@ -1255,12 +1255,11 @@ pool_pending_message_query_set(POOL_PENDING_MESSAGE * message, POOL_QUERY_CONTEX
 }
 
 /*
- * Add one message to the tail of the list
+ * Add one message to the tail of the list.
  */
 void
 pool_pending_message_add(POOL_PENDING_MESSAGE * message)
 {
-       POOL_PENDING_MESSAGE *msg;
        MemoryContext old_context;
 
        if (!session_context)
@@ -1312,8 +1311,7 @@ pool_pending_message_add(POOL_PENDING_MESSAGE * message)
                                (errmsg("pool_pending_message_add: message type: sync")));
 
        old_context = MemoryContextSwitchTo(session_context->memory_context);
-       msg = copy_pending_message(message);
-       session_context->pending_messages = lappend(session_context->pending_messages, msg);
+       session_context->pending_messages = lappend(session_context->pending_messages, message);
        MemoryContextSwitchTo(old_context);
 }
 

diff --git a/src/protocol/pool_proto_modules.c b/src/protocol/pool_proto_modules.c
index de5ea195fdb1b82fd720202d5a13fd72888b47b8..7cba9776a75474787c9ff3a7aa248c5a78b95294 100644 (file)
--- a/src/protocol/pool_proto_modules.c
+++ b/src/protocol/pool_proto_modules.c
@@ -1178,7 +1178,6 @@ Execute(POOL_CONNECTION * frontend, POOL_CONNECTION_POOL * backend,
                pool_pending_message_dest_set(pmsg, query_context);
                pool_pending_message_query_set(pmsg, query_context);
                pool_pending_message_add(pmsg);
-               pool_pending_message_free_pending_message(pmsg);
 
                /* Various take care at the transaction start */
                handle_query_context(backend);
@@ -1580,9 +1579,6 @@ Parse(POOL_CONNECTION * frontend, POOL_CONNECTION_POOL * backend,
                 * deadlock
                 */
                pool_set_query_in_progress();
-#ifdef NOT_USED
-               pool_clear_sync_map();
-#endif
                pool_extended_send_and_wait(query_context, "P", len, contents, 1, MAIN_NODE_ID, true);
                pool_extended_send_and_wait(query_context, "P", len, contents, -1, MAIN_NODE_ID, true);
                pool_add_sent_message(session_context->uncompleted_message);
@@ -1591,7 +1587,6 @@ Parse(POOL_CONNECTION * frontend, POOL_CONNECTION_POOL * backend,
                pmsg = pool_pending_message_create('P', len, contents);
                pool_pending_message_dest_set(pmsg, query_context);
                pool_pending_message_add(pmsg);
-               pool_pending_message_free_pending_message(pmsg);
 
                pool_unset_query_in_progress();
        }
@@ -1759,7 +1754,6 @@ Bind(POOL_CONNECTION * frontend, POOL_CONNECTION_POOL * backend,
                pool_pending_message_dest_set(pmsg, query_context);
                pool_pending_message_query_set(pmsg, query_context);
                pool_pending_message_add(pmsg);
-               pool_pending_message_free_pending_message(pmsg);
        }
 
        if (rewrite_msg)
@@ -1852,7 +1846,6 @@ Describe(POOL_CONNECTION * frontend, POOL_CONNECTION_POOL * backend,
                pool_pending_message_dest_set(pmsg, query_context);
                pool_pending_message_query_set(pmsg, query_context);
                pool_pending_message_add(pmsg);
-               pool_pending_message_free_pending_message(pmsg);
 
                pool_unset_query_in_progress();
        }
@@ -1971,7 +1964,6 @@ Close(POOL_CONNECTION * frontend, POOL_CONNECTION_POOL * backend,
                pool_pending_message_dest_set(pmsg, query_context);
                pool_pending_message_query_set(pmsg, query_context);
                pool_pending_message_add(pmsg);
-               pool_pending_message_free_pending_message(pmsg);
 
                if (session_context->load_balance_node_id != PRIMARY_NODE_ID)
                {
@@ -1979,9 +1971,6 @@ Close(POOL_CONNECTION * frontend, POOL_CONNECTION_POOL * backend,
                        memcpy(query_context->where_to_send, where_to_send_save, sizeof(where_to_send_save));
                }
 
-#ifdef NOT_USED
-               dump_pending_message();
-#endif
                pool_unset_query_in_progress();
 
                /*
@@ -2865,7 +2854,6 @@ ProcessFrontendResponse(POOL_CONNECTION * frontend,
                                pool_unset_query_in_progress();
                                msg = pool_pending_message_create('S', 0, NULL);
                                pool_pending_message_add(msg);
-                               pool_pending_message_free_pending_message(msg);
                        }
                        else if (!pool_is_query_in_progress())
                                pool_set_query_in_progress();
@@ -3787,7 +3775,6 @@ static POOL_STATUS parse_before_bind(POOL_CONNECTION * frontend,
                                pmsg->not_forward_to_frontend = true;
                                pool_pending_message_dest_set(pmsg, new_qc);
                                pool_pending_message_add(pmsg);
-                               pool_pending_message_free_pending_message(pmsg);
                        }
 
                        /* Send parse message to primary node */
@@ -3802,7 +3789,6 @@ static POOL_STATUS parse_before_bind(POOL_CONNECTION * frontend,
                        pmsg->not_forward_to_frontend = true;
                        pool_pending_message_dest_set(pmsg, new_qc);
                        pool_pending_message_add(pmsg);
-                       pool_pending_message_free_pending_message(pmsg);
 
                        /* Replace the query context of bind message */
                        bind_message->query_context = new_qc;
@@ -4266,7 +4252,6 @@ pool_discard_except_sync_and_ready_for_query(POOL_CONNECTION * frontend,
                        {
                                msg = pool_pending_message_create('S', 0, NULL);
                                pool_pending_message_add(msg);
-                               pool_pending_message_free_pending_message(msg);
                                SimpleForwardToBackend(kind, frontend, backend, len, contents);
                                break;
                        }