Good catch. Will implement this. On Wednesday, 20 June 2018 14:45:54 UTC+2, Bart wrote: > > I have found a workaround for this issue. > The root cause is probably something in the pyDal connector or psycopg2 or > threading. I leave the finding of that to the experts. > > The workaround is to add code to gluon/scheduler.py to test the connection > before the rest of the Scheduler.send_heartbeat() function is executed. > If the connection-test fails, a new one is set up: > Insert this code at the top of the Scheduler.send_heartbeat() function > > if self.db_thread: > # BKR 20180612 check if connection still works, if not -> throw away > self.db_thread and force reconnect > try: > x = self.db_thread(self.db_thread.scheduler_worker.worker_name == > self.worker_name).select() > except self.db_thread._adapter.connection.OperationalError: > self.db_thread = None > > > With this addition, the scheduler works okay. > > > Op woensdag 6 juni 2018 21:26:40 UTC+2 schreef Bart: >> >> For a new application, i have installed web2py 2.16.1 under python 3.6 >> and using psycopg2 2.7.4 for postgresql access. >> >> Everything is working okay, except the web2py scheduler. >> >> After successfull execution of the first task, the scheduler gives an >> error in the send_heartbeat function. >> The task output is correctly stored in the database, with status >> COMPLETED. The transaction is committed. >> >> But then in the first heartbeat after completion, the error below is >> thrown: >> >> Looks like the database connection is lost unexpected. >> >> The strange thing is that this is only happening with psycopg2. When the >> PG8000 connector is used, everything is working fine. >> I have tested this on my development system (MacBook) >> >> On my production system under Ubuntu 16.04, the same thing is happening. >> >> Does anyone have a clue? >> >> The error: >> >> ERROR:web2py.scheduler.MyMac.local#21060:Error retrieving status >> Exception in thread Thread-30: >> Traceback (most recent call last): >> File "/Users/me/PycharmProjects/myapp/web2py/gluon/scheduler.py", line >> 1168, in send_heartbeat >> mybackedstatus = db(sw.worker_name == >> self.worker_name).select().first() >> File >> "/Users/me/PycharmProjects/myapp/venv/lib/python3.6/site-packages/pydal/objects.py", >> >> line 2250, in select >> return adapter.select(self.query, fields, attributes) >> File >> "/Users/me/PycharmProjects/myapp/venv/lib/python3.6/site-packages/pydal/adapters/base.py", >> >> line 762, in select >> return self._select_aux(sql, fields, attributes, colnames) >> File >> "/Users/me/PycharmProjects/myapp/venv/lib/python3.6/site-packages/pydal/adapters/base.py", >> >> line 718, in _select_aux >> rows = self._select_aux_execute(sql) >> File >> "/Users/me/PycharmProjects/myapp/venv/lib/python3.6/site-packages/pydal/adapters/base.py", >> >> line 712, in _select_aux_execute >> self.execute(sql) >> File >> "/Users/me/PycharmProjects/myapp/venv/lib/python3.6/site-packages/pydal/adapters/__init__.py", >> >> line 67, in wrap >> return f(*args, **kwargs) >> File >> "/Users/me/PycharmProjects/myapp/venv/lib/python3.6/site-packages/pydal/adapters/base.py", >> >> line 412, in execute >> rv = self.cursor.execute(command, *args[1:], **kwargs) >> psycopg2.OperationalError: server closed the connection unexpectedly >> This probably means the server terminated abnormally >> before or while processing the request. >> >> >> During handling of the above exception, another exception occurred: >> >> Traceback (most recent call last): >> File >> "/usr/local/Cellar/python3/3.6.4_2/Frameworks/Python.framework/Versions/3.6/lib/python3.6/threading.py", >> >> line 916, in _bootstrap_inner >> self.run() >> File "/Users/me/PycharmProjects/myapp/web2py/gluon/scheduler.py", line >> 637, in run >> self.send_heartbeat(counter) >> File "/Users/me/PycharmProjects/myapp/web2py/gluon/scheduler.py", line >> 1239, in send_heartbeat >> db.rollback() >> File >> "/Users/me/PycharmProjects/myapp/venv/lib/python3.6/site-packages/pydal/base.py", >> >> line 704, in rollback >> self._adapter.rollback() >> File >> "/Users/me/PycharmProjects/myapp/venv/lib/python3.6/site-packages/pydal/adapters/__init__.py", >> >> line 56, in wrap >> return f(*args, **kwargs) >> File >> "/Users/me/PycharmProjects/myapp/venv/lib/python3.6/site-packages/pydal/adapters/base.py", >> >> line 865, in rollback >> return self.connection.rollback() >> psycopg2.InterfaceError: connection already closed >> >
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