Unreleased Release Notes

4.8.0

Upgrade Notes

• Applications relying on the threading backend’s brief automatic selection of spawn must now request it explicitly. Existing applications that relied on workers inheriting parent-process state keep the historical fork behavior.

Bug Fixes

• The threading backend once again uses fork by default on platforms where it is available. A service and its configuration being picklable does not guarantee that application state initialized in the parent process is available in a fresh spawn worker.

  Applications that are fully spawn-safe can opt in with service.launch(..., start_method="spawn"). On platforms without fork, spawn remains the default. Explicit spawn requests validate that the service and ConfigOpts can be serialized.