caches: make a set copy to edit it during operation

rhodecode/lib/rc_cache/cache_key_meta.py

@@ -1,53 +1,53 b''
 # -*- coding: utf-8 -*-
 
 # Copyright (C) 2015-2020 RhodeCode GmbH
 #
 # This program is free software: you can redistribute it and/or modify
 # it under the terms of the GNU Affero General Public License, version 3
 # (only), as published by the Free Software Foundation.
 #
 # This program is distributed in the hope that it will be useful,
 # but WITHOUT ANY WARRANTY; without even the implied warranty of
 # MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 # GNU General Public License for more details.
 #
 # You should have received a copy of the GNU Affero General Public License
 # along with this program.  If not, see <http://www.gnu.org/licenses/>.
 #
 # This program is dual-licensed. If you wish to learn more about the
 # RhodeCode Enterprise Edition, including its added features, Support services,
 # and proprietary license terms, please see https://rhodecode.com/licenses/
 
 import os
 import atexit
 import logging
 import signal
 
 log = logging.getLogger(__name__)
 
 cache_keys_by_pid = set()
 
 
 def free_cache_keys(*args):
     ssh_cmd = os.environ.get('RC_CMD_SSH_WRAPPER')
     if ssh_cmd:
         return
 
     from rhodecode.model.db import Session, CacheKey
     log.info('Clearing %s cache keys', len(cache_keys_by_pid))
 
     if cache_keys_by_pid:
         try:
-            for cache_proc in cache_keys_by_pid:
+            for cache_proc in set(cache_keys_by_pid):
                 like_expression = '{}%'.format(cache_proc)
                 CacheKey.query().filter(
                     CacheKey.cache_key.like(like_expression)).delete(synchronize_session='fetch')
                 cache_keys_by_pid.remove(cache_proc)
             Session().commit()
         except Exception:
             log.exception('Failed to clear keys, exiting gracefully')
 
 
 atexit.register(free_cache_keys)
 signal.signal(signal.SIGTERM, free_cache_keys)
 signal.signal(signal.SIGINT, free_cache_keys)