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Apr. 22, 2019
Jan. 31, 2017


REinforcement Learning Algorithms, Autoscaling and eXchange (RELAAX)

RELAAX is a framework designed to:

  1. Simplify research and development of Reinforcement Learning applications by taking care of underlying infrastructure

  2. Provide a usable and scalable implementation of state of the art Reinforcement Learning Algorithms

  3. Ease deployment of Agents and Environments for training and exploitation of the trained Agents at scale on popular cloud platforms

Please find some samples demostrating RELAAX abilities in relaax_sample_apps repository.

The components of RELAAX include:

  • Reinforcement Learning eXchange (RLX) protocol connects RL Agents with an RL Environment

  • RELAAX Agent Proxy wraps details of the RLX Protocol implementation and exposes simple API to be used to exchange States, Rewards, and Actions between the scalable RL Server and Environment.

  • RELAAX Server allows developers to run RL Agents locally or at scale on popular cloud platforms. See more details below.

  • RELAAX provides implementations of popular RL algorithms to simplify RL application development and research.

  • RELAAX is integrated into a hosted service where you can deploy your RL cluster on AWS, GCP, and Azure in just a few steps.


Quick start

We recommended you use an isolated Python environment to run RELAAX. Virtualenv or Anaconda are examples. If you're using the system's python environment, you may need to run pip install commands with sudo and you also have to be sure that you have python-pip installed.

  • Clone RELAAX repo.
git clone
  • Install RELAAX
cd relaax
pip install -e .[all]

Now you have relaax command available to create new applications, run it, configure algorithms, or generate environments and algorithms for your application. To see available options, run:

relaax --help
  • Create new RELAAX application
relaax new app-name
cd app-name

This will create basic RL application with simple multi-handed bandit environment:

app.yaml - contains configuration of environment, all servers, and algorithm
environment - folder with environment and training regime implementation

You could see what other option are available by running:

relaax new --help
  • Run created application. From your application folder, run:
relaax run all

You could see what other option are available by running:

relaax run --help
  • Run different environment You could try other environments. From your application folder, run:
relaax generate -e environment-name

To see what environments are available, run:

relaax generate --help
  • Different configurations Different envoronments would require different algoritm configurations. To see list of available configurations, run:
relaax config

To see how to apply these configurations, run:

relaax config --help
  • Local copy of algorithm implementation If you would like to base your RL algorithm on RELAAX implementation or modify existing implementation you may copy algorithm in your app folder. From your application folder, run:
relaax generate -a algorithm-name

To see what algorithms are available run:

relaax generate --help

Running on Windows

To run RELAAX on Windows we recommend using WinPython distribution. We have tested WinPython 64bit version on Windows 8.1 and Windows 10. You will also need Microsoft Visual C++ Build Tools 14.00 if you want to use OpenAI Gym environments. You can download it here or here.

Once you have installed these distributions you need to run "WinPython Command Prompt.exe", which is located in you WinPython installation directory. This will open a command prompt windows configured to use WinPython as Python distribution. After that you can install relaax using pip:

C:\WinPython-64bit->cd ..
C:\>git clone
C:\>cd relaax
C:\relaax>pip install -e .

This command will install relaax and it's dependencies under WinPython's Python environment. You will need run relaax from WinPython Command Prompt or create a custom shortcut for it.

To add OpenAI Gym support run the following comands (again, from WinPythonCommand Prompt):

C:\WinPython-64bit->pip install gym
C:\WinPython-64bit->pip install git+

Now you can create a test environment to test if everything is working:

C:\WinPython-64bit->cd ..
C:\relaax new bandit-test
C:\>cd bandt-test
C:\bandit-test>relaax run all

This will run a test environment with multi-armed bandit. You should see output in a separate console window.

To test OpenAI Gym environment:

C:\WinPython-64bit->cd ..
C:\relaax new gym-test -e openai-gym
C:\>cd gym-test
C:\gym-test>relaax run all

This will run a CartPole-v0 environment.

System Architecture


  • Environment - computer simulation, game, or "hardware" in real world (say industrial manipulator, robot, car, etc.). To accelerate learning number of Environment(s) could be run in parallel.
  • RELAAX Agent Proxy - simple library which is embedded into Environment. It collects the State and Reward in Environment, sends it to the RELAAX Server, receives back Action(s) and communicates it to the Environment.
  • RLX Server - listens on a port for a connection from the Environment. After connection is accepted it starts Agent and passes control over communication with Environment to that Agent.
  • Parameter Server - one or several nodes which run Global Function NN (Q, value, or policy function). Parameter Server node(s) communicates with Agent over RPC bridge to synchronize state of the Global Function NN with Agents.
  • CheckPoints - storage where Parameter Server saves state of the Global Function NN; when system is re-stared, it may restore Global Function NN state from the stored previously checkpoint and continue learning.
  • Metrics - Evironment, Agent, and Parameter Server send various metrics to the Metrics node; developer may see these metrics in Web Browser by connecting to the Metrics node.

Release Notes


  • All configuration *.yaml files should include the relaax version, for ex.:
version: 1.1.0
  name: policy_gradient
  • All algorithms supports 3 predefined methods for gradients' combining: (except TRPO-based algorithms, where the agents send just experience to the parameter server)

    • fifo: first in first out.
      There are classic scheme which is used by vanilla A3C algorithm. Incoming gradients are applying freely,
      despite if parameter server weights is already changed by the other agent.
    • avg: averaging.
      All gradients is accumulated on parameter server until their amount reaches the number specified by
      num_gradients parameter. After that, the average of the gradients are applied to the parameter server.
    • dc: delay compensation, see related article
      Incoming gradients are applying wisely to the parameter server,
      even if its weights is already changed by the other agent.
      It computes the difference between parameter server & agents weights to recalculate
      agents' gradients wrt delay. And it applies compensated variant to the parameter server.
  • TRPO-based algorithms is split into 3 variants:

      name: trpo
      subtype: trpo-d2              # variants: ppo | trpo-d1 | trpo-d2

    TRPO policy used 1-st order derivatives with trpo-d1 and 2-nd order with trpo-d2.

  • All algorithms supports configured input, which can described directly in the yaml, for ex.:

    version: 1.1.0
      name: da3c
        shape: [7, 7, 3]
        use_convolutions: true
        - type: convolution
          activation: elu
          n_filters: 8
          filter_size: [3, 3]
          stride: [2, 2]
          border: valid
        - type: convolution
          activation: elu
          n_filters: 8
          filter_size: [3, 3]
          stride: [2, 2]
          border: valid
  • All algorithms supports a stacked input state, which could be set by history parameter, for ex.:

    version: 1.1.0
      name: da3c
        shape: [84, 84]             # state: [height, width] or [height, width, channels]
        history: 4                  # number of consecutive states to stuck to represent an input
        use_convolutions: true      # set to True to use convolutions to process the input,
                                    # it uses set of convolutions from universe architecture by default
        universe: false             # set to False to use classic set of A3C convolutions
  • Activations could be setup directly via configuration yaml, for ex.:

      hidden_sizes: [128, 64]       # list of layers sizes, if use_lstm=true-> last size is for LSTM
      activation: relu              # activation for the layers defined in hidden_sizes, except LSTM
  • All activations represents as object, not simple functions as before.
    Thereby they could be heavier, have its own configuration, weights, etc.

  • Kernel based activation (KAF) was added, wrt article.
    It could be additionally configured via yaml, for ex.:

      activation: kaf               # activation for the layers defined in hidden_sizes, except LSTM
        boundary: 2.0               # range of values
        size: 20                    # size of the kernel
        kernel: rbf                 # rbf | rbf2d
        gamma: 1.0                  # configuration constant
  • Dilated LSTM was added, wrt FeUdal Networks for Hierarchical Reinforcement Learning.
    It uses memory granularity due to the division into cores. All LSTM units is divided into parts by simple modulo operation.
    This is represent a dilation when the far parts are updated less depending on their core number.
    It could be additionally configured via yaml, for ex.:

      use_lstm: true                # to use LSTM instead of FF, set to the True
      lstm_type: Dilated            # there are two types of LSTM to use: Basic | Dilated
      lstm_num_cores: 8             # level of granularity for Dilated LSTM within amount of cores
  • Distributed PPO (DPPO) algorithm was added: it is similar to Clipped PPO, described in this article.
    It uses separate neural networks for the policy & critic, also as for its losses wrt backpropagation.

  • Command line was updated and improved for relaax new & relaax generate commands.
    It supports 6 base algorithms and its variants: policy-gradient, da3c, trpo, ddpg, dqn, dppo
    and 4 environment templates: bandit, openai-gym, deepmind-lab, vizdoom (gym-doom)

  • Learning rate scheduling was added (except DDPG & TRPO algorithms).
    It could be configured via yaml, for ex.:

      max_global_step: 30000        # amount of maximum global steps to pass through the training
      use_linear_schedule: true     # set to True to use linear lr annealing wrt max_global_step
      initial_learning_rate: 2e-2   # initial learning rate, which can be anneal by schedule
      learning_rate_end: 2e-3       # final learning rate within schedule
      schedule_step: update         # variants: update | environment (only applicable for DPPO)

    It allows to specify the low boundary for the learning rate annealing procedure.
    If learning_rate_end boundary isn't provided to the schedule, it sets to 0.0.

    DPPO algorithm can uses environment steps or update steps (amount of updates within optmization procedure)
    to perform annealing, where the 2-nd variant is more applicable.

  • Best model checkpoint was added.
    It estimates the model by its score metric, which is calculated as average reward
    within number of batches specified by avg_in_num_batches parameter.

      checkpoint_time_interval: 30  # time interval in seconds to update the checkpoints
      checkpoints_to_keep: 1        # number of last saved checkpoints to keep
      best_checkpoints_to_keep: 3   # top-3 best checkpoints are kept wrt its score metric
      avg_in_num_batches: 10        # model score is calculated within 10 sliding batches
  • Some extensions for the existing algorithms:

    • DA3C & DPPO
      • critic learning rate could be scaled wrt policy learning rate
        by critic_scale parameter. If it equals to 2.0 then value function
        learning rate is two times higher and 0.5 for vice versa.
      • seed parameter was added to reproduce some runs.
      • normalize_advantage: set to true to normalize the advantage
    • DA3C
      • there are 2 entropy types to use: Gauss | Origin.
        Where the 2-nd one is from vanilla A3C article.
      • loss could be clipped by relative parameters:
        policy_clip & critic_clip
    • DPPO
      • entropy: set some value to use entropy penalty
      • l2_coeff: set some value to use L2 regularization for the critic
      • mini_batch: mini_batch size to split on within batch
      • policy_iterations: number of optimization iterations for the policy
      • value_func_iterations: the same for the value function
      • vf_clipped_loss: set to true to use clipped loss for the critic
    • TRPO
      • trajectories could be accumulated by its absolute experience size
        or directly via number of successful trajectories (until terminal): timesteps_per_batch or episodes_per_batch
      • there are 2 linesearch types: Origin | Adaptive
          linesearch_type: Adaptive

RELAAX Agent Proxy

Agent Proxy run with your Environments training and is used to communicate with RL Agents. At the moment client implemented in Python, later on we are planning to implement client code in C/C++, Ruby, GO, etc. to simplify integration of other environments.

Python API:

Available from relaax.environment.agent_proxy import AgentProxy, AgentProxyException

  • connect() - connect to the Agent (through RLX server)
  • init(expoit=False) - send init command to the Agent to give it time to load model and do any other required initialization steps; you may use exploit flag to switch off exploration and traing of the model for the given Agent. Agent would copy latest trained weights from parameter server (PS) and do inferring, but wouldnt update model weights on PS.
  • update(reward=None, state=None, terminal=False) - send update to the Agent with state and reward and indication if this is terminal state or not
  • reset() - send reset command to the Agent
  • metrics.scalar - send scalar to metrics server
  • metrics.histogram - send tensor histogram to metrics server

Agent Proxy is simple but requires certain amout of code to iitialize Agent, connection and reconnect to the Agents, handle exceptions, etc. To simplify all that even further, you may use TrainingBase class, which wrapps all details of the Agent Proxy operations.

Python API:

Avalable from import TrainingBase

  • __init__ - use to instantiate your environment. Base calass will load configuration options and instantiate Agent Proxy. Agent Proxy will be available as self.agent. Following options will be loaded:
    • exploit - passed to Agent Proxy init (this option is passed from commad line)
    • environment/max_episodes - how many episodes to run
    • environment/infinite_run - don't stop after max_episodes reached
  • episode(self, number) - called for each episode; return episode_reward from this method to capture game_score metric

Reinforcement Learning eXchange protocol

Reinforcement Learning eXchange protocol is a simple binary protocol implemented over TCP. It allows to send State of the Environment and Reward to the Server and deliver Action from the Agent to the Environment.


Reinforcement Learning eXchange protocol definition

Message exchange:

{'command': 'init', 'exploit': False|True} -> {'response': 'ready'} OR {'response': 'error', 'message': 'can't initialize agent'}

{'command': 'update', 'terminal': False|True, 'state': [], 'reward': 1} -> {'response': 'action', 'data': 1} OR {'response': 'error', 'message': 'can't update state'}

{'command': 'reset'} -> {'response': 'done'} OR {'response': 'error', 'message': 'can't reset agent'}

{'command': 'update_metrics', 'name': name, 'y': y, 'x': x} -> {'response': 'done'} OR {'response': 'error', 'message': 'can't update metrics'}


Basic types:

Name Value Size in bytes
TYPE_STRING_UTF8 3 variable
TYPE_IMAGE 6 variable
TYPE_NDARRAY 7 variable
TYPE_LIST 8 variable
TYPE_INT64 10 8
TYPE_DICT 11 variable

Message format:

| "[size in bytes]:"|Version(TYPE_UINT4)| key value0 | ... | key valueN | ","

Key/Typed Value format:

| Key name(TYPE_STRING_UTF8)| Type(1 byte) | Value |


| 0(False)/1(True) |


| Length in bytes(TYPE_UINT4) | bytes UTF8 |


| image type(TYPE_STRING_UTF8) | xdim(TYPE_UINT4) | ydim(TYPE_UINT4) | Length in bytes(TYPE_UINT4) | bytes |

image type values: see PIL image doc


| shapes count(TYPE_UINT4) | shape0 |...| shapeN | Length in bytes(TYPE_UINT4) | bytes |

TYPE_LIST value:

| number of items(TYPE_UINT4) | item0 |...| itemN |

TYPE_DICT value:

| number of items(TYPE_UINT4) | key value0 | ... | key valueN |


Update metrics message:

    'command': 'update_metrics',
    'data': [{ 'method': method, 'name': name, 'y': y, 'x': x }, { 'method': method1, 'name': name1, 'y': y1, 'x': x1 }]

RELAAX Servers

RELAAX Server implements dynamic loading of the algorithm implementation. By convention, every algorithm implementation exposes Agent ( and ParameterServer ( classes. RLX Server loads and instattiate Agent model for every incoming connection from Environment. There usually single Parameter Server (PS). PS loads and instantiate ParameterServer class. Every Agent gets RPC connection to PS and could call remotely methods exposed on PS model.

Model(s) on PS should be registered with Session and methods exposed to RPC using Op method. See samples/simple-exchange-js/algorithm/ to very basic sample of the Agent, ParameterServer, and Model implementation and data exchange between them.

RLX Server

Agent API:

  • __init__(self, parameter_server) - Agent instance constructed with pointer to PS which coulld be used to call methods on PS using RPC
  • init(self, exploit=False) - called by the Environment (Agent Proxy) to give Agent time to initialize, load model, and do all necessary preporation to star.
  • update(self, reward, state, terminal) - receive state and reward from the Environmet and should return back action. Terminal indicates terminal state.
  • reset(self) - sent by Environment (Agent Proxy) to reset Agent

Parameter Server

ParameterServer API:

  • init(self) - called when ParameterServer class instantiated. At this point PS should load Model/NN and register it with Session which is used to call model methods. For example:
from relaax.server.common.session import Session
from .model import SharedParameters 
def init(self):
  self.session = Session(SharedParameters())
  • close(self) - called before PS is stopped to close session.
  • create_checkpoint(self) - called by PS to create check point of the Model.

Latest Releases
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