fix(balancer) start only needed upstream update timers

kong/runloop/balancer/init.lua

@@ -25,15 +25,13 @@ local pairs = pairs
 local tostring = tostring
 local table = table
 local table_concat = table.concat
-local timer_at = ngx.timer.at
 local run_hook = hooks.run_hook
 local var = ngx.var
 
 
 local CRIT = ngx.CRIT
 local ERR = ngx.ERR
 local WARN = ngx.WARN
-local DEBUG = ngx.DEBUG
 local EMPTY_T = pl_tablex.readonly {}
 
 
@@ -189,14 +187,7 @@ local function init()
     end
   end
 
-  local _
-  local frequency = kong.configuration.worker_state_update_frequency or 1
-  _, err = timer_at(frequency, upstreams.update_balancer_state)
-  if err then
-    log(CRIT, "unable to start update proxy state timer: ", err)
-  else
-    log(DEBUG, "update proxy state timer scheduled")
-  end
+  upstreams.update_balancer_state()
 end
 
 

kong/runloop/balancer/upstreams.lua

@@ -20,6 +20,7 @@ local timer_at = ngx.timer.at
 
 
 local CRIT = ngx.CRIT
+local DEBUG = ngx.DEBUG
 local ERR = ngx.ERR
 
 local GLOBAL_QUERY_OPTS = { workspace = null, show_ws_id = true }
@@ -232,11 +233,13 @@ local function set_upstream_events_queue(operation, upstream_data)
 end
 
 
-function upstreams_M.update_balancer_state(premature)
+local update_balancer_state_running
+local function update_balancer_state_timer(premature)
   if premature then
     return
   end
 
+  update_balancer_state_running = true
 
   while upstream_events_queue[1] do
     local event  = upstream_events_queue[1]
@@ -250,14 +253,30 @@ function upstreams_M.update_balancer_state(premature)
   end
 
   local frequency = kong.configuration.worker_state_update_frequency or 1
-  local _, err = timer_at(frequency, upstreams_M.update_balancer_state)
+  local _, err = timer_at(frequency, update_balancer_state_timer)
   if err then
+    update_balancer_state_running = false
     log(CRIT, "unable to reschedule update proxy state timer: ", err)
   end
 
 end
 
 
+function upstreams_M.update_balancer_state()
+  if update_balancer_state_running then
+    return
+  end
+
+  local frequency = kong.configuration.worker_state_update_frequency or 1
+  local _, err = timer_at(frequency, update_balancer_state_timer)
+  if err then
+    log(CRIT, "unable to start update proxy state timer: ", err)
+  else
+    log(DEBUG, "update proxy state timer scheduled")
+  end
+end
+
+
 
 
 --------------------------------------------------------------------------------

spec/02-integration/04-admin_api/15-off_spec.lua

@@ -1113,3 +1113,97 @@ describe("Admin API #off with Unique Foreign #unique", function()
     -- assert.equal(references.data[1].unique_foreign.id, unique_reference.unique_foreign.id)
   end)
 end)
+
+describe("Admin API #off worker_consistency=eventual", function()
+
+  local client
+
+  lazy_setup(function()
+    assert(helpers.start_kong({
+      database = "off",
+      lmdb_map_size = LMDB_MAP_SIZE,
+      worker_consistency = "eventual",
+      worker_state_update_frequency = 0.1,
+    }))
+  end)
+
+  lazy_teardown(function()
+    helpers.stop_kong(nil, true)
+  end)
+
+  before_each(function()
+    client = assert(helpers.admin_client())
+  end)
+
+  after_each(function()
+    if client then
+      client:close()
+    end
+  end)
+
+  it("does not increase timer usage (regression)", function()
+    -- 1. configure a simple service
+    local res = assert(client:send {
+      method = "POST",
+      path = "/config",
+      body = helpers.unindent([[
+        _format_version: '1.1'
+        services:
+        - name: konghq
+          url: http://konghq.com
+          path: /
+        plugins:
+        - name: prometheus
+      ]]),
+      headers = {
+        ["Content-Type"] = "text/yaml"
+      },
+    })
+    assert.response(res).has.status(201)
+
+    -- 2. check the timer count
+    res = assert(client:send {
+      method  = "GET",
+      path    = "/metrics",
+    })
+    local res_body = assert.res_status(200, res)
+    local req1_pending_timers = assert.matches('kong_nginx_timers{state="pending"} %d+', res_body)
+    local req1_running_timers = assert.matches('kong_nginx_timers{state="running"} %d+', res_body)
+    req1_pending_timers = assert(tonumber(string.match(req1_pending_timers, "%d")))
+    req1_running_timers = assert(tonumber(string.match(req1_running_timers, "%d")))
+
+    -- 3. update the service
+    res = assert(client:send {
+      method = "POST",
+      path = "/config",
+      body = helpers.unindent([[
+        _format_version: '1.1'
+        services:
+        - name: konghq
+          url: http://konghq.com
+          path: /install#kong-community
+        plugins:
+        - name: prometheus
+      ]]),
+      headers = {
+        ["Content-Type"] = "text/yaml"
+      },
+    })
+    assert.response(res).has.status(201)
+
+    -- 4. check if timer count is still the same
+    res = assert(client:send {
+      method  = "GET",
+      path    = "/metrics",
+    })
+    local res_body = assert.res_status(200, res)
+    local req2_pending_timers = assert.matches('kong_nginx_timers{state="pending"} %d+', res_body)
+    local req2_running_timers = assert.matches('kong_nginx_timers{state="running"} %d+', res_body)
+    req2_pending_timers = assert(tonumber(string.match(req2_pending_timers, "%d")))
+    req2_running_timers = assert(tonumber(string.match(req2_running_timers, "%d")))
+
+    assert.equal(req1_pending_timers, req2_pending_timers)
+    assert.equal(req1_running_timers, req2_running_timers)
+  end)
+
+end)