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name: parallel-actor-critic description: "Guides minimalRL A2C and A3C multiprocessing actor-critic workflows, Gym API migration, and safe process debugging." disable-model-invocation: true metadata: disco-role: operating license: MIT

Parallel Actor-Critic Workflows

Use this sub-skill when a task asks about minimalRL's A2C or A3C scripts, especially synchronous vector rollouts, asynchronous workers, shared models, process lifecycle, or Gym API modernization.

Route by task

• A2C / synchronous vector rollout: read references/api-reference.md for ParallelEnv, worker, and compute_target; read references/workflows.md for the update sequence.
• A3C / asynchronous global-local training: use references/workflows.md for shared model and local gradient flow, then references/troubleshooting.md for worker hangs or missing gradients.
• Gym 0.26 migration: read the migration section in references/workflows.md before running either full native script.
• Safe preflight checks: run scripts/smoke_parallel_actor_critic.py, which avoids full training and unbounded process spawning.

Do not use this sub-skill for

• Single-process REINFORCE, actor-critic, PPO, PPO-LSTM, or V-trace network/update basics; use ../on-policy-discrete/SKILL.md.
• DQN, ACER, or replay/off-policy correction; use ../off-policy-value/SKILL.md.
• DDPG, continuous PPO, or SAC; use ../continuous-control/SKILL.md.

Quick operating workflow

1. Decide whether the user wants A2C's synchronous vectorized rollout or A3C's asynchronous worker updates.

2. Check references/api-reference.md for exact actor-critic, worker, and target-return contracts.

3. If using modern Gym, apply the reset/step/seed migration in references/workflows.md before running full training.

4. Run a bounded smoke check:

   python sub-skills/parallel-actor-critic/scripts/smoke_parallel_actor_critic.py --check all
   

5. For deadlocks, tuple arity failures, gradient-copy bugs, or CPU oversubscription, read references/troubleshooting.md.

Bundled runtime files

• references/api-reference.md records A2C/A3C classes, functions, hyperparameters, worker protocol, and tensor shapes.
• references/workflows.md explains synchronous and asynchronous actor-critic workflows plus Gym migration.
• references/troubleshooting.md gives conservative process-debugging guidance.
• scripts/smoke_parallel_actor_critic.py validates model, target-return, and bounded protocol contracts without full training.