5. Notes regarding the RAMP workers

The RAMP “worker” is the object responsible of actually running (training and evaluating) a submission and returning back the results (predictions and scores). The workers are typically launched from a loop set up for a specific event on the server. The worker can then run the submission either locally on the server or on a remote machine.

The type of worker used in a certain event is specified in the worker section of the yml configuration file, using the worker_type key (see Deploy a specific RAMP event). Additional keys can be required depending on the worker type.

Available workers:

• The ramp_engine.local.CondaEnvWorker will run the submission in a specific isolated conda environment. This worker is specified as worker_type: conda and requires an additional key conda_env specifying the name of the conda environment.

• The ramp_engine.aws.AWSWorker will send the submission to an AWS instance and copy back the results. This worker is specified as worker_type: aws, and for more details on the setup and configuration, see below.

• The ramp_engine.remote.DaskWorker will send the submission to Dask cluster, which can be local or remote, and copy back the results. This worker is specified as worker_type: dask. For more details on the setup and configuration, see below.

5.1. Running submissions in a Conda environment

As previously mentioned, the ramp_engine.local.CondaEnvWorker workers rely on a Conda environment to execute the submission.

For instance, if you would like to run the Iris challenge, the starting kit requires numpy, pandas, and scikit-learn. Thus, the environment used to run the initial submission should have these libraries installed, in addition to ramp-workflow.

Subsequently, you can create such environment and use it in the event configuration:

~ $ conda create --name ramp-iris pip numpy pandas scikit-learn
~ $ conda activate ramp-iris
~ $ pip install ramp-workflow

If you are using a ramp-kit from the Paris-Saclay CDS, each kit will provide either an environment.yml or ami_environment.yml file which you can use to create the environment:

conda create --name ramp-iris --file environment.yml

Alternatively, you can include an environment.yml file inside the ramp-kit directory and use the following to install the environment:

~/ramp_deployment $ ramp setup create-conda-env --event-config events/iris_test/config.yml

You can update an existing environment with the following:

~/ramp_deployment $ ramp setup update-conda-env --event-config events/iris_test/config.yml

5.1.1. Event configuration

Create an event config.yml (see Deploy a specific RAMP event) and update the ‘worker’ section, which should look something like:

ramp:
    problem_name: iris
    event_name: iris_ramp_test
    event_title: "Iris classification challenge"
    event_is_public: true
worker:
    worker_type: conda
    conda_env: ramp-iris
    kit_dir: /home/ramp/ramp_deployment/ramp-kits/iris
    data_dir: /home/ramp/ramp_deployment/ramp-data/iris/data
    submissions_dir: /home/ramp/ramp_deployment/events/iris/submissions
    logs_dir: /home/ramp/ramp_deployment/events/iris/logs
    predictions_dir: /home/ramp/ramp_deployment/events/iris/predictions
    timeout: 14400
dispatcher:
    hunger_policy: sleep
    n_workers: 2
    n_threads: 2
    time_between_collection: 1

Worker configuration

• conda_env: the name of the conda environment to use. If not specified, the base environment will be used.

• kit_dir: path to the directory of the RAMP kit.

• data_dir: path to the directory of the data.

• submissions_dir: path to the directory containing the submissions.

• logs_dir: path to the directory where the log of the submission will be stored.

• predictions_dir: path to the directory where the predictions of the submission will be stored.

• timeout: timeout after a given number of seconds when running the worker. If not provided, a default of 7200 is used.

dispatcher configuration

• hunger_policy: Policy to apply in case that there is no anymore workers to be processed. One of None, ‘sleep’ or ‘exit’, default is None:

  • if None: the dispatcher will work without interruption;

  • if ‘sleep’: the dispatcher will sleep for 5 seconds before to check for new submission;

  • if ‘exit’: the dispatcher will stop after collecting the results of the last submissions.

• n_workers: Maximum number of workers that can run submissions simultaneously.

• n_threads: The number of threads that each worker can use.

• time_between_collection: How long, in seconds, the worker should wait before re-checking if the submission is ready for collection. The default is 1 second.

5.2. Running submissions on Amazon Web Services (AWS)

The AWS worker will train and evaluate the submissions on an AWS instance, which can be useful if the server itself has not much resources or if you need specific resources (e.g. GPU’s). To this end you need to prepare an image based on which RAMP can launch an instance for each submission.

You can do so:

1. you can either create an AWS EC2 instance manually, install everything and load the data and make an image from that instance (see

Prepare AWS image), or

2. make a pipeline with a recipe to create an image

(see Prepare AWS Pipeline).

The latter option has an advantage if you forsee that the image will be updated during the course of the running challenge (e.g. participants demand installing additional Python packages). The first option will require altering the image manually while the latter will update the image automatically by rerunning the pipeline (RAMP will always select the newest version of the image ‘ami_image_name’ (base name of the image) set in the config.yml file of the event.

5.2.1. Prepare AWS image

Please follow the summary steps:

1. Launch AWS instance and connect to it.

2. Prepare the instance for running submissions.

3. Save the instance as an Amazon Machine Image (AMI).

4. Update the event config.yml file on the RAMP server.

5.2.1.1. Launching AWS instance

Follow AWS getting started to launch an Amazon EC2 Linux instance. Amazon can create a new key-pair for your instance, which you can download. You need to store this in a hidden directory (e.g., .ssh/) and change the rights to file permissions to only read for owner. You can use:

~ $ chmod 400 <path_to_aws_key>

To connect to your instance via ssh, use:

~ $ ssh -i /path/my-key-pair.pem my-instance-user-name@my-instance-public-dns-name

'my-instance-user-name' depends on the type of instance you picked but is commonly ‘ec2-user’ or ‘ubuntu’. The full list can be found here under ‘Get the user name for your instance’. ‘my-instance-public-dns-name’ can be found by clicking on your ‘Instances’ tab in your EC2 dashboard. Full connection details can be found in the AWS guide.

5.2.1.2. Prepare the instance

To prepare the instance you need to download the starting kit, data and all required packages to run submissions. This can be saved as an AMI (image) and will then be used to launch instances to run submissions.

Below is a basic guide for creating such an AMI manually, using the Iris challenge. This guide is for an ubuntu instance. If you have a Linux instance you will not need to add miniconda to your ~/.profile but you will need to install git.

• Install miniconda:

  ~ $ LATEST_MINICONDA="http://repo.continuum.io/miniconda/Miniconda3-latest-Linux-x86_64.sh"
  ~ $ wget -q $LATEST_MINICONDA -O ~/miniconda.sh
  ~ $ bash ~/miniconda.sh -b
  ~ $ echo '. ${HOME}/miniconda3/etc/profile.d/conda.sh' >> ~/.profile
  ~ $ echo 'conda activate base' >> ~/.profile
  ~ $ source .profile
  ~ $ conda info
  ~ $ conda update --yes --quiet conda pip
  

• Get the starting kit material (e.g. for ‘iris’):

  ~ $ RAMPKIT_DIR="$HOME/ramp-kits"
  ~ $ project_name="iris"
  ~ $ kit_url="https://github.com/ramp-kits/$project_name"
  ~ $ kit_dir="$RAMPKIT_DIR/$project_name"
  ~ $ git clone $kit_url $kit_dir
  

• Update the base conda environment for the needs of the challenge:

  ~ $ environment="$kit_dir/environment.yml"
  ~ $ conda env update --name base --file $environment
  ~ $ conda list
  

• Get the data and copy private data to ramp-kits/<project>/data/. Note: depending on how prepare_data.py structures the data files, the last command may differ:

  ~ $ RAMPDATA_DIR="$HOME/ramp-data"
  ~ $ data_url="https://github.com/ramp-data/$project_name"
  ~ $ data_dir="$RAMPDATA_DIR/$project_name"
  ~ $ git clone $data_url $data_dir
  ~ $ cd $data_dir
  ~ $ python prepare_data.py
  ~ $ cp data/private/* $kit_dir/data/
  

• Test the kit:

  ~ $ cd $kit_dir
  ~ $ ramp-test
  

Next, save the instance as an AMI. Starting from the instance tab: Actions -> Image -> Create image. See Create an AMI from an Amazon EC2 instance for more details.

5.2.2. Prepare AWS Pipeline

Reference: AWS guidelines

To prepare the AMI Image AWS Pipeline log in into your AWS account.

Follow the three steps:

1. create a components

2. create an image recipe

3. create a pipeline

Ad. 1 To create a component search for image pipelines and navigate to the Components tab on the menu bar on the left hand side. Click a button ‘Create component’. Then select:

• ‘Build’ as component type

• type the name of the component

• component version (e.g. 1.0.0)

• Define document content. Here is the template of what you might want to use:

  constants:
    - Home:
      type: string
      value: /home/ubuntu
    - Challenge:
      type: string
      value: $CHALLENGE_NAME
    - OSF_username:
      type: string
      value: $USERNAME
    - OSF_password:
      type: string
      value: $PASSWORD
  phases:
    - name: Build
      steps:
        - name: install_system
          action: ExecuteBash
          inputs:
            commands:
              - |
                set -e
                echo "===== Updating package cache and git ====="
  
                sudo apt update
                sudo apt install --no-install-recommends --yes git
  
                echo "===== Done ====="
  
        - name: install_conda
          action: ExecuteBash
          inputs:
            commands:
              - |
                set -e
                echo "===== Install conda and mamba ====="
  
                wget -q https://github.com/conda-forge/miniforge/releases/latest/download/Miniforge3-Linux-x86_64.sh -O miniconda.sh
                bash ./miniconda.sh -b -p {{ Home }}/miniconda
                export PATH={{ Home }}/miniconda/bin:$PATH
                conda init
                conda install -y --quiet python pip mamba
  
                echo "===== Done ====="
  
        - name: add_conda_to_user_path
          action: ExecuteBash
          inputs:
            commands:
              - |
                set -e
                echo "===== Setup conda for user ubuntu ====="
  
                # Always run .bashrc for bash even when it is not interactive
                sed -e '/# If not running interactively,/,+5d' -i {{ Home }}/.bashrc
                # Run conda init to allow using conda in the bash
                sudo -u ubuntu bash -c 'export PATH={{ Home }}/miniconda/bin:$PATH && conda init'
                echo "Added conda in PATH for user ubuntu"
  
                echo "===== Done ====="
  
  
        - name: install_gpu_related
          action: ExecuteBash
          inputs:
            commands:
              - |
                set -e
                echo "===== Installing Nvidia drivers for GPUs ====="
  
                # Install the nvidia drivers to be able to use the GPUs
                # Use the headless version to avoid installing unrelated
                # library related to display capabilities
  
                sudo apt install --no-install-recommends --yes nvidia-headless-440 nvidia-utils-440
  
                echo "===== Done ====="
  
        - name: install_challenge
          action: ExecuteBash
          inputs:
            commands:
              - |
                set -e
                echo "===== Installing Dependencies ====="
  
                export PATH={{ Home }}/miniconda/bin:$PATH
  
                # clone the challenge files
                git clone https://github.com/ramp-kits/{{ Challenge }}.git {{ Home }}/{{ Challenge }}
  
                # Choose one of these options to install dependencies:
  
                # 1. Use the package from conda, using mamba to accelerate the
                # environment resolution
                mamba env update --name base --file {{ Home }}/{{ Challenge }}/environment.yml
  
                # 2. Use pip to install packages. In this case, make sure to
                # install all needed dependencies beforehand using apt.
                pip install -r {{ Home }}/{{ Challenge }}/requirements.txt
                pip install -r {{ Home }}/{{ Challenge }}/extra_libraries.txt
  
                echo "===== Done ====="
  
  
        - name: download_data
          action: ExecuteBash
          timeoutSeconds: 7200
          inputs:
            commands:
              - |
                set -e
                echo "===== Downloading Private Data ====="
  
                cd {{ Home }}/{{ Challenge }}
                export PATH={{ Home }}/miniconda/bin:$PATH
                python download_data.py --private --username {{ OSF_username }} --password {{ OSF_password }}
  
                # Make sure everything is owned by
                chown -R ubuntu {{ Home }}
  
                echo "===== Done ====="
  
    - name: test
      steps:
        - name: test_ramp_install
          action: ExecuteBash
          inputs:
            commands:
              - |
                set -e
                echo "===== Test ramp install ====="
  
                cd {{ Home }}/{{ Challenge }}
                sudo -u ubuntu BASH_ENV={{ Home }}/.bashrc bash -c 'conda info'
                # Run a ramp-test for the starting kit to make sure everything is running properly
                sudo -u ubuntu BASH_ENV={{ Home }}/.bashrc bash -c 'ramp-test --submission starting_kit --quick-test'
  
                echo "====== Done ======"
  

where you should exchange ‘$CHALLENGE_NAME’ for the name of the challenge you wish to use (here we are pointing to repositories stored on the ramp-kits github repository), and ‘$USERNAME’ and ‘$PASSWORD’ for your credentials on OSF where you stored the data for the challenge. Of course this is just a suggestion. Feel free to make your own, custom file.

Note: If you prefer using S3 from AWS to store and load your data you can follow the instructions on how to do that here: AWS configure envvars docs

You will need to create a new IAM user with the rights to access S1 and then exchange the lines for download in your .yml file with:

export AWS_ACCESS_KEY_ID=key_received_on_creating_a_user
export AWS_SECRET_ACCESS_KEY=key_received_on_creating_a_user
export AWS_DEFAULT_REGION=the_zone_you_use  # eg eu-west-1
aws S3 cp --recursive s3://your_bucket_name_on_S3/

Once you have the component ready we progress to Image recipe:

Ad 2. Select the tab ‘Image recipes’ and then click the button ‘Create image recipe’. Fill in the name, version and optionally the description for this recipe. Then select:

• Select managed Images

• Ubuntu (you might prefer to choose different operating system, but keep in mind that the default user may differ. For ubuntu it is ‘ubuntu’ for Linux it is ‘ec2-user’. You will need to know your default user when writing the config.yml file for your event and/or to ssh to your instance)

• quick start (Amazon-managed)

• Ubuntu Server 20 LTS x86

• Use latest available OS version

• working directory path: ‘/tmp’

• if you have a large dataset consider increasing the memory, eg to 16 GiB

Next, choose the component. From the drop down list select ‘Owned by me’ and select the component you created in the previous step.

Scroll down and click the button ‘Create recipe’.

Ad 3. Select ‘Image pipelines’ from the left-hand side menu bar. Click the button ‘Create image pipeline’. Next:

• Choose the name for your pipeline and optionally the description

• Enable enhanced metadata collection

• Build schedule: Manual

• click ‘Next’

• select ‘Use existing recipe’ and choose your recipe from the drop down menu

• click ‘Next’

• Create infrastructure configuration using service defaults

• click ‘Next’

• click ‘Next’

• review your pipeline and press ‘Create pipeline’

Congratulations! You have just created a pipeline for your ramp event. Let’s now run it making sure that everything works as expected.

To create an image select your pipeline and from ‘Actions’ select ‘Run pipeline’. You can also select ‘View details’ to follow creation of the pipeline. Relax, it will take a while.

In case there is a failure when running your pipeline you can search for logs on CloudWatch to view more precisely what has happened.

Once your pipeline is successfully created you can search for ‘EC2’. There, in the menu on your left-hand side you will find ‘AMIs’ tab. Click on it.

You should be able to find all your available images, also the one just created. Note that if you run the same pipeline next time the new AMI will appear with the same name but of different version. Ramp always searches for the newest version of the image (as long as you specify the correct base name in the config.yml file).

To make sure that everything works as expected it is advised that you create an instance from that image and connect to it through ssh. Check if all the expected files are there and that you can run the ramp-test without issues. Also, if you wish to be able to use GPU make sure that your python code recognizes them, you can also use the command:

nvidia-smi -l 3

To make sure that your nvidia driver is correctly installed

5.2.3. Event configuration

Create an event config.yml (see Deploy a specific RAMP event) and update the ‘worker’ section, which should look something like:

ramp:
    problem_name: iris
    event_name: iris_ramp_aws_test
    event_title: "iris ramp aws test"
    event_is_public: true
worker:
    worker_type: aws
    access_key_id: <aws_access_key_id for boto3 Session>
    secret_access_key: <aws_secret_access_key for boto3 Session>
    region_name: us-west-2 # oregon
    ami_image_name: <name of the AMI set up for this event>
    ami_user_name: ubuntu
    instance_type: t2.micro
    use_spot_instance: false
    key_name: <name of your pem file, eg iris_key>
    security_group: launch-wizard-103
    key_path: <path to pem file corresponding to user name, eg my_path/iris_key.pem>
    remote_ramp_kit_folder: /home/ubuntu/ramp-kits/iris
    submissions_dir: /home/ramp/ramp_deployment/events/iris_aws/submissions
    predictions_dir: /home/ramp/ramp_deployment/events/iris_aws/predictions
    logs_dir: /home/ramp/ramp_deployment/events/iris_aws/logs
    memory_profiling: false
dispatcher:
    hunger_policy: sleep
    n_workers: 5
    n_threads: 2
    time_between_collection: 60

Worker configuration

• access_key_id and secret_access_key: to create a new access key, go to your top navigation bar, click on your user name -> My Security Credentials. Open the ‘Access keys’ tab then click on ‘Create New Access Key’. You will be prompted to download your ‘access key ID’ and ‘secret access key’ to a .csv file, which should be saved in a secure location. You can also use an existing access key by obtaining the ID and key from your saved .csv file. See Managing Access Keys for more details.

• region_name: zone of your instance, which can be found in the EC2 console, ‘Instances’ tab on the left, under ‘availability zone’.

• ami_image_name: name you gave to the image you prepared (see Prepare the instance). This can be found in the EC2 console, under ‘Images’ -> ‘AMI’ tab. Note: you don’t have to put the entire image name and if you indicate the generic name you chose, it will automatically take the latest version of the image created running the pipeline (e.g. ‘challenge-iris’ will point to ‘challenge-iris 2022-04-19T17-19-18.405Z’ if it’s the latest one)

• ami_user_name: user name you used to ssh into your instance. Commonly ‘ec2-user’ or ‘ubuntu’.

• instance_type: found in the EC2 console, ‘Instances’ tab, ‘Description’ tab at the bottom, under ‘Instance type’.

• use_spot_instance: boolean, default false. Whether or not to use spot instances. See AWS for more information on spot instances.

• key_name: name of the key, eg if your key file is ‘iris_key.pem’, the key name is ‘iris_key’

• security_group: in the EC2 console, ‘Instances’ tab, ‘Description’ tab at the bottom, under ‘Security groups’.

• key_path: path to the you private key used to ssh to your instance (see Launching AWS instance). Note that you need to copy your key into the RAMP. It is best to give the absolute path. Ensure the permissions of this file is set to only ‘read’ by owner (which can be done using chmod 400 key_name.pem command).

• remote_ramp_kit_folder: path to the starting kit folder on the AWS image you prepared (see Prepare the instance).

• submissions_dir: path to the submissions directory on the RAMP server.

• predictions_dir: path to the predictions directoryon the RAMP server.

• logs_dir: path to store the submission logs on the RAMP server.

• memory_profiling: boolean, whether or not to profile memory used by each submission. You need to install memory profiler in your prepared AMI image to enable this.

Dispatcher configuration

• hunger_policy: See dispatcher_configuration.

• n_workers: Maximum number of workers that can run submissions simultaneously. For AWS workers, this means the maximum number of instances that can be run at one time. This should fall within your AWS instance limit.

• n_threads: The number of threads that each worker can use. This would depend on the AWS instance type you have chosen.

• time_between_collection: How long, in seconds, the worker should wait before re-checking if the submission is ready for collection. The default is 1 second. For AWS workers the check for collection will be done through SSH. If the time between checks is too small, the repetitive SSH requests may be potentially blocked by the cloud provider. We advise to set this configuration to at least 60 seconds.

5.3. Running submissions with Dask

ramp_engine.remote.DaskWorker allows to run submissions on a Dask distributed cluster which can be either remote or local.

To setup this worker please follow the instructions below.

5.3.1. DaskWorker setup of the main server

1. Setup the ramp_frontend server and deploy the RAMP event.

2. Install dask.distributed,

   $ pip install "dask[distributed]"
   

2. Start a dask.distributed scheduler,

   $ dask-scheduler
   

   See dask.distributed documentation for more information.

3. Specify the worker in the event configuration as follows,

   worker:
     worker_type: dask
     conda_env: ramp-iris
     dask_scheduler: "tcp://127.0.0.1:8786"   # or another URL to the dask scheduler
     n_workers: 4  # (number of RAMP workers launched in parallel. Must be smaller
                   #  than the number of dask.distributed workers)
   

4. Launch the RAMP dispatcher.

5.3.2. DaskWorker setup with a local cluster

To start a local dask.distributed cluster, run

$ dask-worker --nprocs 10  # or any appropriate number of workers.

See dask.distributed documentation for more information.

Note

The number of dask.distributed workers (as specified by the --nprocs argument) must be larger, ideally by 50% or so, than the number of RAMP workers specified in the event configuration. For instance, on a machine having 16 physical CPUs, you can start 16 RAMP workers, and 32 dask.distributed workers.

This is necessary as some dask.distributed workers will be used for running the submission, while others manage data and state synchronization.

5.3.3. DaskWorker setup with a remote cluster

To use a remote dask.distributed cluster, following pre-requisites must be verified.

• the remote machine must have a ramp_deployment folder with the same absolute path as on the main server

• it must have a base (or ramp-board) environment with the same versions of installed packages as on the main server. Including the same version of dask[distributed].

The setup steps are then as follows,

1. Create the conda environment for running event submissions (same name as on the main server).

2. Copy ramp-kit and ramp-data of the event from the main server, to the identical paths under the ramp_deployment folder.

3. Start the dask[distributed] workers,

   $ dask-worker --nprocs 10  # or any appropriate number of workers.
   

   Note

   If the Dask scheduler is not in the same local network as the Dask workers, you would need to start workers as,

   dask-worker tcp://<scheduler-public-ip>:8786 --listen-address "tcp://0.0.0.0:<port>" --contact-address "tcp://<worker-public-ip>:<port>
   

   This however only works with one dask worker at the time. To start more, you can use the following bash script,

   # Select the number of dask workers to start.
   # Better to start at idx=10, to keep the number of digits
   # (mapped to the port) constant.
   for idx in {10..28}
   do
       # start dask worker in the background
       dask-worker tcp://<scheduler-public-ip>:8786 --listen-address "tcp://0.0.0.0:416${idx}"   --contact-address "tcp://<worker-public-ip>:416${idx}" --nthreads 4  &
       sleep 0.5
   done
   
   echo "Sleeping"
   while [ 1 ]
   do
       sleep 1
   done
   
   # On exit kill all children processes (i.e. all workers)
   trap "trap - SIGTERM && kill -- -$$" SIGINT SIGTERM EXIT
   

   which in particular allows to kill all workers with Ctrl+C when interrupting this script.

Security considerations

By default communications between dask distributed schedulers and workers is neither encrypted not authenticated which poses security risks. Dask distributed supports TLS/SSL certifications, however these are not currently supported in DaskWorker in RAMP.

A workaround for authentication could be to configure a firewall, such as UFW to deny connections to dask related ports, except from pre-defined IPs of dask worker/scheduler.

Warning

Do not run the following command without understanding what they do. You could lose SSH access to you machine.

For instance with the UFW firewall on the main server,

sudo ufw allow 22/tcp   # allow SSH
sudo ufw allow 80
sudo ufw allow 443      # allow access to ramp_frontend server over HTTP and HTTPS
sudo ufw allow from <remote-worker-ip>  # allow access to any port from a given IP
sudo ufw enable
sudo ufw status

5.4. Create your own worker

Currently, the choice of workers in RAMP is quite limited. You might want to create your own worker for your platform (Openstack, Azure, etc.). This section illustrates how to implement your own worker.

Your new worker should subclass ramp_engine.base.BaseWorker. This class implements some basic functionalities which you should use.

The setup function will initialize the worker before it can be used, e.g. activate the right conda environment. Your worker should implement this class and call super at the end of it. Indeed, the base class is in charge of updating the status of the worker and logging some information. Thus, your function should look like:

def setup(self):
      # implement some initialization for instance launch an
      # Openstack instance
      assert True
      # call the base class to update the status and log
      super().setup()

Similarly, you might need to make some operation to release the worker. Then, the function teardown is in charge of this. It should be called similarly to the setup function:

def teardown(self):
      # clean some jobs done by the worker
      # ...
      # call the base class to update the status and log
      super().teardown()

The actual job of the worker should be implemented in launch_submission in charge of running a submission and collect_results in charge of collecting and paste them in the location indicated by the dispatcher. As for the other previous functions, you should call super at the end of the processing to update the status of the worker:

def launch_submission(self):
      # launch ramp test --submission <sub> --save-output on the Openstack
      # instance
      ...
      # call the base class to update the status and log
      super().launch_submission()

Once a submission is trained, the ramp test command line would store the results and you should upload those in the directory indicated by the dispatcher:

def collect_results(self):
      # the base class will be in charge of checking that the state of
      # the worker is fine
      super().collect_results()
      # write the prediction and logs at the location indicated by the
      # dispatcher (given by the config file)
      log_output = stdout + b'\n\n' + stderr
      log_dir = os.path.join(self.config['logs_dir'],
                             self.submission)
      if not os.path.exists(log_dir):
          os.makedirs(log_dir)
      with open(os.path.join(log_dir, 'log'), 'wb+') as f:
          f.write(log_output)
      pred_dir = os.path.join(self.config['predictions_dir'],
                              self.submission)
      output_training_dir = os.path.join(
          self.config['submissions_dir'], self.submission,
          'training_output')
      if os.path.exists(pred_dir):
          shutil.rmtree(pred_dir)
      shutil.copytree(output_training_dir, pred_dir)
      self.status = 'collected'
      logger.info(repr(self))
      return (self._proc.returncode, error_msg)

You need to implement the _is_submission_finished function to indicate the worker that he can call the collect_results function. This function will be dependent of the platform that you are using. For instance, for a conda worker, it would look like:

def _is_submission_finished(self):
  """Status of the submission.

  The submission was launched in a subprocess. Calling ``poll()`` will
  indicate the status of this subprocess.
  """
  return False if self._proc.poll() is None else True