From 1aad435d527018dd0ccd65c526440fec2867bae5 Mon Sep 17 00:00:00 2001
From: Alexey Milovidov <milovidov@yandex-team.ru>
Date: Sat, 3 Mar 2018 17:39:16 +0300
Subject: [PATCH] Fixed race condition at startup [#CLICKHOUSE-2]

---
 dbms/src/Common/Config/ConfigReloader.cpp | 8 +++++++-
 dbms/src/Common/Config/ConfigReloader.h   | 3 +++
 dbms/src/Server/Server.cpp                | 3 +++
 3 files changed, 13 insertions(+), 1 deletion(-)

diff --git a/dbms/src/Common/Config/ConfigReloader.cpp b/dbms/src/Common/Config/ConfigReloader.cpp
index 53a5aa61cfa..54cbf507055 100644
--- a/dbms/src/Common/Config/ConfigReloader.cpp
+++ b/dbms/src/Common/Config/ConfigReloader.cpp
@@ -24,7 +24,11 @@ ConfigReloader::ConfigReloader(
 {
     if (!already_loaded)
         reloadIfNewer(/* force = */ true, /* throw_on_error = */ true, /* fallback_to_preprocessed = */ true);
+}
 
+
+void ConfigReloader::start()
+{
     thread = std::thread(&ConfigReloader::run, this);
 }
 
@@ -35,7 +39,9 @@ ConfigReloader::~ConfigReloader()
     {
         quit = true;
         zk_node_cache.getChangedEvent().set();
-        thread.join();
+
+        if (thread.joinable())
+            thread.join();
     }
     catch (...)
     {
diff --git a/dbms/src/Common/Config/ConfigReloader.h b/dbms/src/Common/Config/ConfigReloader.h
index 2dcbea7a8bc..94b2d3c629c 100644
--- a/dbms/src/Common/Config/ConfigReloader.h
+++ b/dbms/src/Common/Config/ConfigReloader.h
@@ -39,6 +39,9 @@ public:
 
     ~ConfigReloader();
 
+    /// Call this method to run the backround thread.
+    void start();
+
 private:
     void run();
 
diff --git a/dbms/src/Server/Server.cpp b/dbms/src/Server/Server.cpp
index 44d4bb602c5..9e957dce461 100644
--- a/dbms/src/Server/Server.cpp
+++ b/dbms/src/Server/Server.cpp
@@ -473,6 +473,9 @@ int Server::main(const std::vector<std::string> & /*args*/)
         for (auto & server : servers)
             server->start();
 
+        main_config_reloader->start();
+        users_config_reloader->start();
+
         {
             std::stringstream message;
             message << "Available RAM = " << formatReadableSizeWithBinarySuffix(getMemoryAmount()) << ";"