graphite: init() kills previous fiber if exist

Author: patapenka-alexey

metrics/plugins/graphite.lua

@@ -92,9 +92,14 @@ function graphite.init(opts)
     local sock = socket('AF_INET', 'SOCK_DGRAM', 'udp')
     assert(sock ~= nil, 'Socket creation failed')
 
+    -- require('config'):reload() triggers calling only validate() and apply()
+    -- role's methods without stop().
+    -- so, we should kill previous fiber if exist.
     for name in pairs(GRAPHITE_FIBERS) do
         if name == graphite_fiber.name then
-            error('failed to start fiber: ' .. graphite_fiber.name .. ", already exist")
+            fiber.kill(GRAPHITE_FIBERS[name].fiber)
+            GRAPHITE_FIBERS[name] = nil
+            require('fiber').yield()
         end
     end
 

test/plugins/graphite_test.lua

@@ -221,3 +221,30 @@ g.test_graphite_stop_custom_fiber = function(cg)
         t.assert_equals(count_workers(), 0)
     end)
 end
+
+g.test_graphite_double_start = function(cg)
+    cg.server:exec(function()
+        local fiber = require('fiber')
+        local fun = require('fun')
+        local graphite = require('metrics.plugins.graphite')
+
+        local function count_workers()
+            return fun.iter(fiber.info()):
+                filter(function(_, x) return string.find(x.name, 'metrics_graphite_worker') end):
+                length()
+        end
+
+        t.assert_equals(count_workers(), 0)
+
+        graphite.init({})
+
+        t.assert_equals(count_workers(), 1)
+
+        graphite.init({})
+
+        t.assert_equals(count_workers(), 1)
+
+        graphite.stop()
+        t.assert_equals(count_workers(), 0)
+    end)
+end