Added another test for deadlock

dbms/tests/queries/0_stateless/01007_r1r2_w_r2r1_deadlock.sh

+#!/usr/bin/env bash
+
+CURDIR=$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)
+. $CURDIR/../shell_config.sh
+
+set -e
+
+$CLICKHOUSE_CLIENT --query "DROP TABLE IF EXISTS a"
+$CLICKHOUSE_CLIENT --query "DROP TABLE IF EXISTS b"
+
+$CLICKHOUSE_CLIENT --query "CREATE TABLE a (x UInt8) ENGINE = MergeTree ORDER BY tuple()"
+$CLICKHOUSE_CLIENT --query "CREATE TABLE b (x UInt8) ENGINE = MergeTree ORDER BY tuple()"
+
+
+function thread1()
+{
+    while true; do 
+        seq 1 100 | awk '{ print "SELECT x FROM a WHERE x IN (SELECT toUInt8(count()) FROM system.tables);" }' | $CLICKHOUSE_CLIENT -n
+    done
+}
+
+function thread2()
+{
+    while true; do 
+        seq 1 100 | awk '{ print "SELECT x FROM b WHERE x IN (SELECT toUInt8(count()) FROM system.tables);" }' | $CLICKHOUSE_CLIENT -n
+    done
+}
+
+function thread3()
+{
+    while true; do 
+        $CLICKHOUSE_CLIENT --query "ALTER TABLE a MODIFY COLUMN x Nullable(UInt8)"
+        $CLICKHOUSE_CLIENT --query "ALTER TABLE a MODIFY COLUMN x UInt8"
+    done
+}
+
+function thread4()
+{
+    while true; do 
+        $CLICKHOUSE_CLIENT --query "ALTER TABLE b MODIFY COLUMN x Nullable(UInt8)"
+        $CLICKHOUSE_CLIENT --query "ALTER TABLE b MODIFY COLUMN x UInt8"
+    done
+}
+
+# https://stackoverflow.com/questions/9954794/execute-a-shell-function-with-timeout
+export -f thread1;
+export -f thread2;
+export -f thread3;
+export -f thread4;
+
+TIMEOUT=10
+
+timeout $TIMEOUT bash -c thread1 2> /dev/null &
+timeout $TIMEOUT bash -c thread2 2> /dev/null &
+timeout $TIMEOUT bash -c thread3 2> /dev/null &
+timeout $TIMEOUT bash -c thread4 2> /dev/null &
+
+wait
+
+$CLICKHOUSE_CLIENT --query "DROP TABLE a"
+$CLICKHOUSE_CLIENT --query "DROP TABLE b"