def _put_conn(self, conn):
        """
        Put a connection back into the pool.

        :param conn:
            Connection object for the current host and port as returned by
            :meth:`._new_conn` or :meth:`._get_conn`.

        If the pool is already full, the connection is closed and discarded
        because we exceeded maxsize. If connections are discarded frequently,
        then maxsize should be increased.

        If the pool is closed, then the connection will be closed and discarded.
        """
        try:
            self.pool.put(conn, block=False)
            return  # Everything is dandy, done.
        except __HOLE__:
            # self.pool is None.
            pass
        except Full:
            # This should never happen if self.block == True
            log.warning(
                "Connection pool is full, discarding connection: %s",
                self.host)

        # Connection never got put back into the pool, close it.
        if conn:
            conn.close()
dataset/ETHPy150Open kennethreitz/requests/requests/packages/urllib3/connectionpool.py/HTTPConnectionPool._put_conn