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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


return run_safe(run, print_error=False, **kwargs)
def run(cmd, cache_duration_secs=0, **kwargs):
    def do_run(cmd):
        return bootstrap.run(cmd, **kwargs)
    if cache_duration_secs <= 0:
        return do_run(cmd)
    hash = md5(cmd)
    cache_file = CACHE_FILE_PATTERN.replace('*', hash)
    mkdir(os.path.dirname(CACHE_FILE_PATTERN))
    if os.path.isfile(cache_file):
        
        mod_time = os.path.getmtime(cache_file)
        time_now = now()
        if mod_time > (time_now - cache_duration_secs):
            f = open(cache_file)
            result = f.read()
            f.close()
            return result
    result = do_run(cmd)
    f = open(cache_file, 'w+')
    f.write(result)
    f.close()
    clean_cache()
    return result
def clone(item):