add stress test for async inserts

tests/queries/0_stateless/02015_async_inserts_stress_long.reference

@@ -0,0 +1 @@
+OK

tests/queries/0_stateless/02015_async_inserts_stress_long.sh

@@ -0,0 +1,72 @@
+#!/usr/bin/env bash
+set -e
+
+CURDIR=$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)
+# shellcheck source=../shell_config.sh
+. "$CURDIR"/../shell_config.sh
+
+function insert1()
+{
+    url="${CLICKHOUSE_URL}&async_insert_mode=1&wait_for_async_insert=0"
+    while true; do
+        ${CLICKHOUSE_CURL} -sS "$url" -d 'INSERT INTO async_inserts FORMAT CSV
+1,"a"
+2,"b"
+'
+    done
+}
+
+function insert2()
+{
+    url="${CLICKHOUSE_URL}&async_insert_mode=1&wait_for_async_insert=0"
+    while true; do
+        ${CLICKHOUSE_CURL} -sS "$url" -d 'INSERT INTO async_inserts FORMAT JSONEachRow {"id": 5, "s": "e"} {"id": 6, "s": "f"}'
+    done
+}
+
+function select1()
+{
+    while true; do
+        ${CLICKHOUSE_CLIENT} -q "SELECT * FROM async_inserts FORMAT Null"
+    done
+}
+
+function select2()
+{
+    while true; do
+        ${CLICKHOUSE_CLIENT} -q "SELECT * FROM system.asynchronous_inserts FORMAT Null"
+    done
+}
+
+function truncate1()
+{
+    while true; do
+        sleep 0.1
+        ${CLICKHOUSE_CLIENT} -q "TRUNCATE TABLE async_inserts"
+    done
+}
+
+${CLICKHOUSE_CLIENT} -q "DROP TABLE IF EXISTS async_inserts"
+${CLICKHOUSE_CLIENT} -q "CREATE TABLE async_inserts (id UInt32, s String) ENGINE = MergeTree ORDER BY id"
+
+TIMEOUT=10
+
+export -f insert1
+export -f insert2
+export -f select1
+export -f select2
+export -f truncate1
+
+for _ in {1..5}; do
+    timeout $TIMEOUT bash -c insert1 &
+    timeout $TIMEOUT bash -c insert2 &
+done
+
+timeout $TIMEOUT bash -c select1 &
+timeout $TIMEOUT bash -c select2 &
+timeout $TIMEOUT bash -c truncate1 &
+
+wait
+echo "OK"
+
+${CLICKHOUSE_CLIENT} -q "DROP TABLE IF EXISTS async_inserts";