Wait for IDiskRemote thread pool properly

ASan report [1]:

    WARNING: ThreadSanitizer: heap-use-after-free (pid=611)
      Read of size 4 at 0x7b48006f0250 by thread T273:
        0 MemoryTracker::allocImpl() obj-x86_64-linux-gnu/../src/Common/MemoryTracker.cpp:105:49 (clickhouse+0xa05d0ef)
        1 MemoryTracker::allocImpl() obj-x86_64-linux-gnu/../src/Common/MemoryTracker.cpp:239:22 (clickhouse+0xa05d580)
        2 MemoryTracker::alloc(long) obj-x86_64-linux-gnu/../src/Common/MemoryTracker.cpp:246:5 (clickhouse+0xa05dea7)
        3 DB::ThreadStatus::~ThreadStatus() obj-x86_64-linux-gnu/../src/Common/ThreadStatus.cpp:154:28 (clickhouse+0xa059b01)
        4 ThreadFromGlobalPool::ThreadFromGlobalPool<>()::'lambda'()::operator()() obj-x86_64-linux-gnu/../s>

      Previous write of size 8 at 0x7b48006f0250 by main thread:
        8 std::__1::unordered_map<std::__1::basic_string<>, DB::ProcessListForUser, std::__1::hash<>, std::__1>
        9 DB::ProcessList::~ProcessList() obj-x86_64-linux-gnu/../src/Interpreters/ProcessList.h:275:7 (clickhouse+0x17b71c9c)
        10 DB::ContextSharedPart::~ContextSharedPart() obj-x86_64-linux-gnu/../src/Interpreters/Context.cpp:304:5 (clickhouse+0x17b70712)
        13 DB::SharedContextHolder::reset() obj-x86_64-linux-gnu/../src/Interpreters/Context.cpp:453:44 (clickhouse+0x17b3daf9)
        14 DB::Server::main()::$_8::o>

      Thread T273 (tid=946, running) created by thread T223 at:
        0 pthread_create <null> (clickhouse+0x9f7d49d)
        15 DB::WriteBufferFromS3::makeSinglepartUpload() obj-x86_64-linux-gnu/../src/IO/WriteBufferFromS3.cpp:332:9 (clickhouse+0x17a81b6a)

  [1]: https://s3.amazonaws.com/clickhouse-test-reports/35072/19be9c8c6433ffd1bbf8eb08975d8afbaebf3d43/stress_test__thread__actions_.html

Signed-off-by: Azat Khuzhin <[email protected]>

src/Interpreters/Context.cpp

@@ -29,6 +29,7 @@
 #include <Storages/CompressionCodecSelector.h>
 #include <Storages/StorageS3Settings.h>
 #include <Disks/DiskLocal.h>
+#include <Disks/IDiskRemote.h>
 #include <TableFunctions/TableFunctionFactory.h>
 #include <Interpreters/ActionLocksManager.h>
 #include <Interpreters/ExternalLoaderXMLConfigRepository.h>
@@ -293,6 +294,17 @@ struct ContextSharedPart
 
     ~ContextSharedPart()
     {
+        /// Wait for thread pool for background writes,
+        /// since it may use per-user MemoryTracker which will be destroyed here.
+        try
+        {
+            IDiskRemote::getThreadPoolWriter().wait();
+        }
+        catch (...)
+        {
+            tryLogCurrentException(__PRETTY_FUNCTION__);
+        }
+
         try
         {
             shutdown();