Update environment variables for JAX backend

PiperOrigin-RevId: 886971839

Author: guptaaka

pathwaysutils/experimental/shared_pathways_service/isc_pathways.py

@@ -123,6 +123,18 @@ def _deploy_pathways_proxy_server(
   _logger.info("Successfully deployed Pathways proxy.")
 
 
+def _restore_env_var(key: str, original_value: str | None) -> None:
+  """Restores an environment variable to its original value or unsets it."""
+  if original_value is None:
+    _logger.info("Unsetting environment variable: %s", key)
+    os.environ.pop(key, None)
+  else:
+    _logger.info(
+        "Restoring environment variable '%s' to '%s'", key, original_value
+    )
+    os.environ[key] = original_value
+
+
 class _ISCPathways:
   """Class for managing TPUs for interactive supercomputing.
 
@@ -163,6 +175,10 @@ def __init__(
     self._proxy_port = None
     self.proxy_server_image = proxy_server_image
     self.proxy_options = proxy_options or ProxyOptions()
+    self._old_jax_platforms = None
+    self._old_jax_backend_target = None
+    self._old_jax_platforms_config = None
+    self._old_jax_backend_target_config = None
 
   def __repr__(self):
     return (
@@ -176,6 +192,15 @@ def __repr__(self):
 
   def __enter__(self):
     """Enters the context manager, ensuring cluster exists."""
+    self._old_jax_platforms = os.environ.get(_JAX_PLATFORMS_KEY)
+    self._old_jax_backend_target = os.environ.get(_JAX_BACKEND_TARGET_KEY)
+    self._old_jax_platforms_config = getattr(
+        jax.config, _JAX_PLATFORMS_KEY, None
+    )
+    self._old_jax_backend_target_config = getattr(
+        jax.config, _JAX_BACKEND_TARGET_KEY, None
+    )
+
     try:
       _deploy_pathways_proxy_server(
           pathways_service=self.pathways_service,
@@ -199,11 +224,17 @@ def __enter__(self):
       )
 
       # Update the JAX backend to use the proxy.
+      os.environ[_JAX_PLATFORMS_KEY] = _JAX_PLATFORM_PROXY
+      os.environ[
+          _JAX_BACKEND_TARGET_KEY
+      ] = f"{_JAX_BACKEND_TARGET_HOSTNAME}:{self._proxy_port}"
+
       jax.config.update(_JAX_PLATFORMS_KEY, _JAX_PLATFORM_PROXY)
       jax.config.update(
           _JAX_BACKEND_TARGET_KEY,
           f"{_JAX_BACKEND_TARGET_HOSTNAME}:{self._proxy_port}",
       )
+
       pathwaysutils.initialize()
       _logger.info(
           "Interactive supercomputing proxy client ready for cluster '%s'.",
@@ -221,7 +252,7 @@ def __exit__(self, exc_type, exc_value, traceback):
     _logger.info("Exiting ISCPathways context.")
     self._cleanup()
 
-  def _cleanup(self):
+  def _cleanup(self) -> None:
     """Cleans up resources created by the ISCPathways context."""
     # 1. Clear JAX caches and run garbage collection.
     _logger.info("Starting Pathways proxy cleanup.")
@@ -248,6 +279,16 @@ def _cleanup(self):
     gke_utils.delete_gke_job(self._proxy_job_name)
     _logger.info("Pathways proxy GKE job deletion complete.")
 
+    # 4. Restore JAX variables.
+    _logger.info("Restoring JAX env and config variables...")
+    _restore_env_var(_JAX_PLATFORMS_KEY, self._old_jax_platforms)
+    _restore_env_var(_JAX_BACKEND_TARGET_KEY, self._old_jax_backend_target)
+    jax.config.update(_JAX_PLATFORMS_KEY, self._old_jax_platforms_config)
+    jax.config.update(
+        _JAX_BACKEND_TARGET_KEY, self._old_jax_backend_target_config
+    )
+    _logger.info("JAX variables restored.")
+
 
 @contextlib.contextmanager
 def connect(