chore: import upstream snapshot with attribution

rllib/examples/envs/classes/env_with_subprocess.py

@@ -0,0 +1,43 @@
+import atexit
+import os
+import subprocess
+
+import gymnasium as gym
+from gymnasium.spaces import Discrete
+
+
+class EnvWithSubprocess(gym.Env):
+    """An env that spawns a subprocess."""
+
+    # Dummy command to run as a subprocess with a unique name
+    UNIQUE_CMD = "sleep 20"
+
+    def __init__(self, config):
+        self.UNIQUE_FILE_0 = config["tmp_file1"]
+        self.UNIQUE_FILE_1 = config["tmp_file2"]
+        self.UNIQUE_FILE_2 = config["tmp_file3"]
+        self.UNIQUE_FILE_3 = config["tmp_file4"]
+
+        self.action_space = Discrete(2)
+        self.observation_space = Discrete(2)
+        # Subprocess that should be cleaned up.
+        self.subproc = subprocess.Popen(self.UNIQUE_CMD.split(" "), shell=False)
+        self.config = config
+        # Exit handler should be called.
+        atexit.register(lambda: self.subproc.kill())
+        if config.worker_index == 0:
+            atexit.register(lambda: os.unlink(self.UNIQUE_FILE_0))
+        else:
+            atexit.register(lambda: os.unlink(self.UNIQUE_FILE_1))
+
+    def close(self):
+        if self.config.worker_index == 0:
+            os.unlink(self.UNIQUE_FILE_2)
+        else:
+            os.unlink(self.UNIQUE_FILE_3)
+
+    def reset(self, *, seed=None, options=None):
+        return 0, {}
+
+    def step(self, action):
+        return 0, 0, True, False, {}