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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


pass
def make_http_request(url, data=None, headers=None, method='GET'):
    if is_string(method):
        method = requests.__dict__[method.lower()]
    return method(url, headers=headers, data=data, auth=NetrcBypassAuth(), verify=False)
class SafeStringIO(io.StringIO):
    """ Safe StringIO implementation that doesn't fail if str is passed in Python 2. """
    def write(self, obj):
        if six.PY2 and isinstance(obj, str):
            obj = obj.decode('unicode-escape')
        return super(SafeStringIO, self).write(obj)
def clean_cache(file_pattern=CACHE_FILE_PATTERN,
        last_clean_time=last_cache_clean_time, max_age=CACHE_MAX_AGE):
    mutex_clean.acquire()
    time_now = now()
    try:
        if last_clean_time['time'] > time_now - CACHE_CLEAN_TIMEOUT:
            return
        for cache_file in set(glob.glob(file_pattern)):
            mod_time = os.path.getmtime(cache_file)
            if time_now > mod_time + max_age:
                rm_rf(cache_file)
        last_clean_time['time'] = time_now
    finally:
        mutex_clean.release()
    return time_now
def truncate(data, max_length=100):