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We have several Kinesis streams set up with event notifications that trigger lambdas.  When the LAMBDA_EXECUTOR is set to 'docker' and we send a large number or records to Kinesis, multiple Lambdas will execute, but currently they are failing to create with error:

```
Exception: Lambda process returned error status code: 1. Output:
time="2019-09-18T17:28:11Z" level=error msg="error getting events from daemon: net/http: request canceled" 
Error response from daemon: driver failed programming external connectivity on endpoint busy_sanderson (a78e45a41d0ce5b0d8bab6ff54344fc34fe2b4969f55bf568e753121abc8759e): Bind for 0.0.0.0:38763 failed: port is already allocated
```

I believe this is due to the new debug_java_port introduced with this PR https://github.com/localstack/localstack/pull/1523

With this change, you are setting the port in the constructor by using a method known to have a race condition (https://github.com/localstack/localstack/blob/master/localstack/utils/common.py#L354)
(https://gist.github.com/gabrielfalcao/20e567e188f588b65ba2)

This should be changed to ensure unique ports are being issued across all lambdas


0 if the container does not exist.
        """
        with self.docker_container_lock:
            
            container_name = self.get_container_name(func_arn)
            
            
            
            cmd = ("docker ps -a --filter name='%s' "
                   '--format "{{ .Status }} - {{ .Names }}" '
                   '| grep -w "%s" | cat') % (container_name, container_name)
            LOG.debug('Getting status for container "%s": %s' % (container_name, cmd))
            cmd_result = run(cmd)
            
            container_status = cmd_result.strip()
            if len(container_status) == 0:
                return 0
            if container_status.lower().startswith('up '):
                return 1
            return -1
    def get_docker_container_network(self, func_arn):
        """
        Determine the network of a docker container.
        :param func_arn: The ARN of the lambda function.
        :return: name of the container network
        """
        with self.docker_container_lock:
            status = self.get_docker_container_status(func_arn)
            
            if status == 0: