mark_dead() in ConnectionPool always removes the first connection in the pool

[tongwang]

ConnectionPool's mark_dead() method is supposed to remove the dead connection from the connections list:

self.connections.remove(connection)

However the equality comparison implementation __eq__ in the Connection class is incorrect. It always returns True as long as both objects are Connection instances:

def __eq__(self, other):
        if not isinstance(other, Connection):
            raise TypeError(
                "Unsupported equality check for %s and %s" % (self, other)
            )
        return True

This defect manifests itself by removing all good connections until the connections is empty. One dead connection will bring down the whole connection pool.

Proposed solution: removing __eq__ from Connection. Thoughts?

[honzakral]

That is definitely the correct solution, would you be open to sending a PR?

Thank you!

[alexk307]

Took a stab at it here: #1048

[alexk307]

I ended up modifying the __eq__ method on the Connection object to just use the __hash__ method for equality comparison. I think we also could have deleted the __eq__ method entirely; either way would work IMHO.