Add test.

src/Core/Settings.h

@@ -224,6 +224,7 @@ class IColumn;
     /** Settings for testing hedged requests */ \
     M(Milliseconds, sleep_in_send_tables_status_ms, 0, "Time to sleep in sending tables status response in TCPHandler", 0) \
     M(Milliseconds, sleep_in_send_data_ms, 0, "Time to sleep in sending data in TCPHandler", 0) \
+    M(UInt64, unknown_packet_in_send_data, 0, "Send unknown packet instead of data Nth data packet", 0) \
     \
     M(Bool, insert_allow_materialized_columns, 0, "If setting is enabled, Allow materialized columns in INSERT.", 0) \
     M(Seconds, http_connection_timeout, DEFAULT_HTTP_READ_BUFFER_CONNECTION_TIMEOUT, "HTTP connection timeout.", 0) \

src/Server/TCPHandler.cpp

@@ -1463,12 +1463,20 @@ void TCPHandler::sendData(const Block & block)
 
     try
     {
+        /// For testing hedged requests
+        const Settings & settings = query_context->getSettingsRef();
+        if (settings.unknown_packet_in_send_data)
+        {
+            --const_cast<SettingFieldUInt64 &>(settings.unknown_packet_in_send_data).value;
+            if (settings.unknown_packet_in_send_data == 0)
+                writeVarUInt(UInt64(-1), *out);
+        }
+
         writeVarUInt(Protocol::Server::Data, *out);
         /// Send external table name (empty name is the main table)
         writeStringBinary("", *out);
 
         /// For testing hedged requests
-        const Settings & settings = query_context->getSettingsRef();
         if (block.rows() > 0 && settings.sleep_in_send_data_ms.totalMilliseconds())
         {
             out->next();

tests/queries/0_stateless/01822_async_read_from_socket_crash.sh

@@ -0,0 +1,9 @@
+#!/usr/bin/env bash
+
+CURDIR=$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)
+# shellcheck source=../shell_config.sh
+. "$CURDIR"/../shell_config.sh
+
+
+
+for _ in {1..10}; do $CLICKHOUSE_CLIENT -q "select number from remote('127.0.0.{2,3}', numbers(20)) limit 8 settings max_block_size = 2, unknown_packet_in_send_data=4, sleep_in_send_data_ms=100, async_socket_for_remote=1 format Null" 2>&1 > /dev/null; done