proper destruction order of AsyncLoader::Pool fields

src/Common/AsyncLoader.cpp

@@ -49,6 +49,7 @@ void logAboutProgress(LoggerPtr log, size_t processed, size_t total, AtomicStopw
 AsyncLoader::Pool::Pool(const AsyncLoader::PoolInitializer & init)
     : name(init.name)
     , priority(init.priority)
+    , max_threads(init.max_threads > 0 ? init.max_threads : getNumberOfPhysicalCPUCores())
     , thread_pool(std::make_unique<ThreadPool>(
         init.metric_threads,
         init.metric_active_threads,
@@ -56,17 +57,16 @@ AsyncLoader::Pool::Pool(const AsyncLoader::PoolInitializer & init)
         /* max_threads = */ std::numeric_limits<size_t>::max(), // Unlimited number of threads, we do worker management ourselves
         /* max_free_threads = */ 0, // We do not require free threads
         /* queue_size = */0)) // Unlimited queue to avoid blocking during worker spawning
-    , max_threads(init.max_threads > 0 ? init.max_threads : getNumberOfPhysicalCPUCores())
 {}
 
 AsyncLoader::Pool::Pool(Pool&& o) noexcept
     : name(o.name)
     , priority(o.priority)
-    , thread_pool(std::move(o.thread_pool))
     , ready_queue(std::move(o.ready_queue))
     , max_threads(o.max_threads)
     , workers(o.workers)
     , suspended_workers(o.suspended_workers.load()) // All these constructors are needed because std::atomic is neither copy-constructible, nor move-constructible. We never move pools after init, so it is safe.
+    , thread_pool(std::move(o.thread_pool))
 {}
 
 void cancelOnDependencyFailure(const LoadJobPtr & self, const LoadJobPtr & dependency, std::exception_ptr & cancel)

src/Common/AsyncLoader.h

@@ -365,11 +365,11 @@ private:
     {
         const String name;
         const Priority priority;
-        std::unique_ptr<ThreadPool> thread_pool; // NOTE: we avoid using a `ThreadPool` queue to be able to move jobs between pools.
         std::map<UInt64, LoadJobPtr> ready_queue; // FIFO queue of jobs to be executed in this pool. Map is used for faster erasing. Key is `ready_seqno`
         size_t max_threads; // Max number of workers to be spawn
         size_t workers = 0; // Number of currently executing workers
         std::atomic<size_t> suspended_workers{0}; // Number of workers that are blocked by `wait()` call on a job executing in the same pool (for deadlock resolution)
+        std::unique_ptr<ThreadPool> thread_pool; // NOTE: we avoid using a `ThreadPool` queue to be able to move jobs between pools.
 
         explicit Pool(const PoolInitializer & init);
         Pool(Pool&& o) noexcept;