diff --git a/kong/db/dao/targets.lua b/kong/db/dao/targets.lua
index 1f6ed251..69f45d70 100644
--- a/kong/db/dao/targets.lua
+++ b/kong/db/dao/targets.lua
@@ -186,6 +186,8 @@ end
 function _TARGETS:select_by_upstream_raw(upstream_pk, ...)
   local targets = {}

+  local ips = {}
+
   -- Note that each_for_upstream is not overridden, so it returns "raw".
   for target, err, err_t in self:each_for_upstream(upstream_pk, ...) do
     if not target then
@@ -198,9 +200,12 @@ function _TARGETS:select_by_upstream_raw(upstream_pk, ...)
     end
     target.target = formatted_target

+    table.insert(ips, target.target .. "(order: " .. tostring(target.order) .. ")")
     table.insert(targets, target)
   end

+  ngx.log(ngx.DEBUG, "mark-l207: select_by_upstream_raw targets: ", table.concat(ips, ", "))
+
   table.sort(targets, sort_targets)

   return targets
diff --git a/kong/runloop/balancer.lua b/kong/runloop/balancer.lua
index 1d178f38..d005292b 100644
--- a/kong/runloop/balancer.lua
+++ b/kong/runloop/balancer.lua
@@ -129,14 +129,16 @@ do
       return nil, err, err_t
     end

+    local ips = {}
     -- perform some raw data updates
     for _, target in ipairs(target_history) do
       -- split `target` field into `name` and `port`
       local port
       target.name, port = string.match(target.target, "^(.-):(%d+)$")
       target.port = tonumber(port)
+      table.insert(ips, target.name .. ":" .. port .. "(order: " .. tostring(target.order) .. ")")
     end
-
+    log(DEBUG, "mark-l141: fetched targets: ", table.concat(ips, ", "))
     return target_history
   end
   _load_targets_into_memory = load_targets_into_memory
@@ -458,6 +460,11 @@ local function check_target_history(upstream, balancer)
     (old_history[old_size] or EMPTY_T).order ==
     (new_history[new_size] or EMPTY_T).order then
     -- No history update is necessary in the balancer object.
+    local o = old_history[old_size] or EMPTY_T
+    local n = new_history[new_size] or EMPTY_T
+    log(DEBUG, "mark-l464: check target no change, old: order " , o.order , ", target "
+      , o.target , ", weight " , o.weight
+      , ", new: order " , n.order , ", target " , n.target , ", weight " , n.weight)
     return true
   end

@@ -615,6 +622,13 @@ local function on_target_event(operation, target)
   local ok, err = check_target_history(upstream, balancer)
   if not ok then
     log(ERR, "failed checking target history for ", upstream.name, ":  ", err)
+  else
+    local hosts = balancer.hosts
+    local ips = {}
+    for _, host in ipairs(hosts) do
+      table.insert(ips, host.hostname .. ":" .. host.port)
+    end
+    log(DEBUG, "mark-l624: ips after check ", table.concat(ips,", "), ", operation ", operation, ", target ", target.target)
   end
 end