From ed618d3be1e7b171a1e19b79fd493460418b9954 Mon Sep 17 00:00:00 2001
From: Nikolay Degterinsky <evillique@gmail.com>
Date: Wed, 6 Dec 2023 04:24:43 +0000
Subject: [PATCH] Fix crash in clickhouse-local

---
 src/Interpreters/Context.cpp                        |  2 +-
 src/Interpreters/Context.h                          |  2 +-
 src/Storages/System/StorageSystemServerSettings.cpp | 13 ++++++++-----
 .../02933_local_system_setting.reference            |  0
 .../0_stateless/02933_local_system_setting.sh       |  7 +++++++
 5 files changed, 17 insertions(+), 7 deletions(-)
 create mode 100644 tests/queries/0_stateless/02933_local_system_setting.reference
 create mode 100755 tests/queries/0_stateless/02933_local_system_setting.sh

diff --git a/src/Interpreters/Context.cpp b/src/Interpreters/Context.cpp
index 0a8a8f1f529..a4dff302420 100644
--- a/src/Interpreters/Context.cpp
+++ b/src/Interpreters/Context.cpp
@@ -4830,7 +4830,7 @@ void Context::initializeBackgroundExecutorsIfNeeded()
     shared->are_background_executors_initialized = true;
 }
 
-bool Context::areBackgroundExecutorsInitialized()
+bool Context::areBackgroundExecutorsInitialized() const
 {
     SharedLockGuard lock(shared->background_executors_mutex);
     return shared->are_background_executors_initialized;
diff --git a/src/Interpreters/Context.h b/src/Interpreters/Context.h
index 8c169dd664f..b6bec5ba5d0 100644
--- a/src/Interpreters/Context.h
+++ b/src/Interpreters/Context.h
@@ -1208,7 +1208,7 @@ public:
 
     /// Background executors related methods
     void initializeBackgroundExecutorsIfNeeded();
-    bool areBackgroundExecutorsInitialized();
+    bool areBackgroundExecutorsInitialized() const;
 
     MergeMutateBackgroundExecutorPtr getMergeMutateExecutor() const;
     OrdinaryBackgroundExecutorPtr getMovesExecutor() const;
diff --git a/src/Storages/System/StorageSystemServerSettings.cpp b/src/Storages/System/StorageSystemServerSettings.cpp
index 3a3acabc5a3..439e3972bc7 100644
--- a/src/Storages/System/StorageSystemServerSettings.cpp
+++ b/src/Storages/System/StorageSystemServerSettings.cpp
@@ -46,17 +46,20 @@ void StorageSystemServerSettings::fillData(MutableColumns & res_columns, Context
         {"max_concurrent_insert_queries", std::to_string(context->getProcessList().getMaxInsertQueriesAmount())},
         {"max_concurrent_select_queries", std::to_string(context->getProcessList().getMaxSelectQueriesAmount())},
 
-        {"background_pool_size", std::to_string(context->getMergeMutateExecutor()->getMaxThreads())},
-        {"background_move_pool_size", std::to_string(context->getMovesExecutor()->getMaxThreads())},
-        {"background_fetches_pool_size", std::to_string(context->getFetchesExecutor()->getMaxThreads())},
-        {"background_common_pool_size", std::to_string(context->getCommonExecutor()->getMaxThreads())},
-
         {"background_buffer_flush_schedule_pool_size", std::to_string(CurrentMetrics::get(CurrentMetrics::BackgroundBufferFlushSchedulePoolSize))},
         {"background_schedule_pool_size", std::to_string(CurrentMetrics::get(CurrentMetrics::BackgroundSchedulePoolSize))},
         {"background_message_broker_schedule_pool_size", std::to_string(CurrentMetrics::get(CurrentMetrics::BackgroundMessageBrokerSchedulePoolSize))},
         {"background_distributed_schedule_pool_size", std::to_string(CurrentMetrics::get(CurrentMetrics::BackgroundDistributedSchedulePoolSize))}
     };
 
+    if (context->areBackgroundExecutorsInitialized())
+    {
+        updated.insert({"background_pool_size", std::to_string(context->getMergeMutateExecutor()->getMaxThreads())});
+        updated.insert({"background_move_pool_size", std::to_string(context->getMovesExecutor()->getMaxThreads())});
+        updated.insert({"background_fetches_pool_size", std::to_string(context->getFetchesExecutor()->getMaxThreads())});
+        updated.insert({"background_common_pool_size", std::to_string(context->getCommonExecutor()->getMaxThreads())});
+    }
+
     const auto & config = context->getConfigRef();
     ServerSettings settings;
     settings.loadSettingsFromConfig(config);
diff --git a/tests/queries/0_stateless/02933_local_system_setting.reference b/tests/queries/0_stateless/02933_local_system_setting.reference
new file mode 100644
index 00000000000..e69de29bb2d
diff --git a/tests/queries/0_stateless/02933_local_system_setting.sh b/tests/queries/0_stateless/02933_local_system_setting.sh
new file mode 100755
index 00000000000..c6d19f2445f
--- /dev/null
+++ b/tests/queries/0_stateless/02933_local_system_setting.sh
@@ -0,0 +1,7 @@
+#!/usr/bin/env bash
+
+CURDIR=$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)
+# shellcheck source=../shell_config.sh
+. "$CURDIR"/../shell_config.sh
+
+$CLICKHOUSE_LOCAL -q "select * from system.server_settings format Null;"