I have written a simple service which takes data from network, massages it until it's useful enough, and sends the results out periodically via HTTP to an API.
It all works for a while, then I get an error like this approximately 40 minutes into the service's uptime: ResponseNeverReceived: [<twisted.python.failure.Failure OpenSSL.SSL.ZeroReturnError: >] Then a couple more like this: ResponseNeverReceived: [<twisted.python.failure.Failure twisted.internet.error.ConnectionLost: Connection to the other side was lost in a non-clean fashion: Connection lost.>] Then it ends with TimeoutError: User timeout caused connection failure. Then every request results in the same TimeoutError. I don't know if using HTTPS important in this case. Restarting the whole service, of course, makes the problem go for a while. The other side is the Slack API, so I rather assume it's not very much to blame, it can be demonstrated to work rather reliably, all its criticisms notwithstanding. I cannot yet tell if this bug is a function of uptime, or the number of requests made. I have tried to work around the problem by discarding the agent object, and using an HTTPConnectionPool with persistent=False, but it didn't help at all. I think it made the problem worse because the framework seems to refer to some objects the Agent creates, and the process becomes a CPU hogs in a couple hours (with the TimeoutErrors still happening all the time). The closest I've got on the internets which describes a similar problem, apart from people complaining on StackOverflow about precisely this to happen when they are using Scrapy, is this blog post from almost a decade ago: http://www.chris-wong.net/twisted-web-framework-user-timeout-caused-connection-failure/ . There could be a small chance I'm holding it wrong(tm), but maybe there exists a ticket, just worded differently, which could help me get to the bottom of it. -- Yaroslav Fedevych IT Philosopher
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