Hi!

I have an Elixir application that is ingesting messages from a queue (AWS SQS). It is based off this design that uses GenStage.

The design is as follows:

• GenStage Producer that fetches messages from the queue
• GenStage Consumer that subscribes to Producer, receives the queue message and deletes it from the queue

The application runs smoothly with the exception of a failure that occurs 1-2 times every hour.
It seems that the GenStage Consumer is being sent the following message (which is not accounted for and hence fails):
{:sslsocket, {:gen_tcp, #Port<0.XXXX>, :tls_connection, :undefined}, #PID<0.XXXX.0>}}

I’m racking my brain trying to understand how this might be occurring. There are no explicit messages being sent to the consumer in my application code. The consumers are relatively simple as well - they’re simply using ExAws to make requests to AWS through their API. I don’t make any calls to :gen_tcp at any point.

I’m curious if anybody has encountered something similar or had any ideas about what might be going on.

For context:

Elixir Version:
1.5

Dependencies:

• configparser_ex
• credo
• dialyxir
• distillery
• ex_aws
• excoveralls
• gen_stage
• hackney
• httpoison
• mock
• poison
• sentry
• sshex
• sweet_xml
• timex