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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 re.sub(r'^%s/(.*)$' % config.TMP_FOLDER,
                    r'%s/\1' % config.HOST_TMP_FOLDER, path)
class LambdaExecutorLocal(LambdaExecutor):
    def _execute(self, func_arn, func_details, event, context=None, version=None):
        lambda_cwd = func_details.cwd
        environment = func_details.envvars.copy()
        
        queue = Queue()
        lambda_function = func_details.function(version)
        def do_execute():
            
            if lambda_cwd:
                os.chdir(lambda_cwd)
            if environment:
                os.environ.update(environment)
            result = lambda_function(event, context)
            queue.put(result)
        process = Process(target=do_execute)
        with CaptureOutput() as c:
            process.run()
        result = queue.get()
        
        log_output = ''
        for stream in (c.stdout(), c.stderr()):
            if stream:
                log_output += ('\n' if log_output else '') + stream