Added command execution time measurement

  This will be useful to keep track of possible performance degradation when code changes.

testgres/plugins/pg_probackup2/pg_probackup2/app.py

@@ -56,6 +56,7 @@ def __init__(self, test_class: unittest.TestCase,
         self.verbose = init_params.verbose
         self.archive_compress = init_params.archive_compress
         self.test_class.output = None
+        self.execution_time = None
 
     def run(self, command, gdb=False, old_binary=False, return_id=True, env=None,
             skip_log_directory=False, expect_error=False, use_backup_dir=True):
@@ -113,11 +114,15 @@ def run(self, command, gdb=False, old_binary=False, return_id=True, env=None,
                 cmdline = ['gdbserver'] + ['localhost:' + str(gdb_port)] + cmdline
                 print("pg_probackup gdb suspended, waiting gdb connection on localhost:{0}".format(gdb_port))
 
+            start_time = time.time()
             self.test_class.output = subprocess.check_output(
                 cmdline,
                 stderr=subprocess.STDOUT,
                 env=env
             ).decode('utf-8', errors='replace')
+            end_time = time.time()
+            self.execution_time = end_time - start_time
+
             if command[0] == 'backup' and return_id:
                 # return backup ID
                 for line in self.test_class.output.splitlines():