glusterd: Optimize code to copy dictionary in handshake code path

Problem: While high no. of volumes are configured around 2000
         glusterd has bottleneck during handshake at the time
         of copying dictionary

Solution: To avoid the bottleneck serialize a dictionary instead
          of copying key-value pair one by one

Change-Id: I9fb332f432e4f915bc3af8dcab38bed26bda2b9a
fixes: bz#1711297
Signed-off-by: Mohit Agrawal <moagrawal@redhat.com>

1 files changed, 19 insertions, 8 deletions

diff --git a/xlators/mgmt/glusterd/src/glusterd-rpc-ops.c b/xlators/mgmt/glusterd/src/glusterd-rpc-ops.c
index a6c157e6abb..86ae48c6d6f 100644
--- a/xlators/mgmt/glusterd/src/glusterd-rpc-ops.c
+++ b/xlators/mgmt/glusterd/src/glusterd-rpc-ops.c
@@ -1528,11 +1528,9 @@ glusterd_rpc_friend_add(call_frame_t *frame, xlator_t *this, void *data)
 
     RCU_READ_UNLOCK;
 
-    ret = glusterd_add_volumes_to_export_dict(&peer_data);
-    if (ret) {
-        gf_msg(this->name, GF_LOG_ERROR, 0, GD_MSG_DICT_SET_FAILED,
-               "Unable to add list of volumes "
-               "in the peer_data dict for handshake");
+    peer_data = dict_new();
+    if (!peer_data) {
+        errno = ENOMEM;
         goto out;
     }
 
@@ -1563,10 +1561,23 @@ glusterd_rpc_friend_add(call_frame_t *frame, xlator_t *this, void *data)
         }
     }
 
-    ret = dict_allocate_and_serialize(peer_data, &req.vols.vols_val,
-                                      &req.vols.vols_len);
-    if (ret)
+    /* Don't add any key-value in peer_data dictionary after call this function
+     */
+    ret = glusterd_add_volumes_to_export_dict(peer_data, &req.vols.vols_val,
+                                              &req.vols.vols_len);
+    if (ret) {
+        gf_msg(this->name, GF_LOG_ERROR, 0, GD_MSG_DICT_SET_FAILED,
+               "Unable to add list of volumes "
+               "in the peer_data dict for handshake");
         goto out;
+    }
+
+    if (!req.vols.vols_len) {
+        ret = dict_allocate_and_serialize(peer_data, &req.vols.vols_val,
+                                          &req.vols.vols_len);
+        if (ret)
+            goto out;
+    }
 
     ret = glusterd_submit_request(
         peerinfo->rpc, &req, frame, peerinfo->peer, GLUSTERD_FRIEND_ADD, NULL,