DBT fails to close many connections

[beckjake]

Issue

During tests, with warning output turned on, I see many ResourceWarnings about failing to close sockets.

Issue description

When running make test or any other way of running integration tests, I get a ton of warnings like this:
ResourceWarning: unclosed <socket.socket fd=3564, family=AddressFamily.AF_INET, type=SocketKind.SOCK_STREAM, proto=0, laddr=('10.0.0.32', 2183), raddr=('172.217.1.42', 443)>

Those warnings are generated when a socket object is garbage collected and has not yet been close()d, which means we're leaking sockets. It's possible this is test-only, but that seems unlikely - tests are just the only place where we don't suppress warnings. Since the warning happens during GC, the log part about file, line number, etc are totally useless.

It's possible that #962 would fix this, since we'd potentially be more careful with pooling issues, but I want this to be an explicit issue.

I thought there was also a related user-submitted issue about us holding open redshift or postgres connections indefinitely as well, but I cannot find it.

Results

I expect no warnings!

System information

This is running on dev/guion-bluford but I'm pretty sure dbt has always done this.

The operating system you're running on:
Inside a docker container, or on appveyor, it doesn't matter.

The python version you're using (probably the output of python --version):
Python 3.6

Steps to reproduce

Run the tests :)

[drewbanin]

@beckjake do you think this is still an issue?

[beckjake]

I actually haven't seen these in a while, though I don't think we did anything to deserve that!

[beckjake]

Edit: I should note, we still do see these at DEBUG level when bigquery runs end, because google's libraries don't close their sockets, but I don't think that's going to get fixed.