From 852b7b4c995148239bafa21398bd9dae711bae1d Mon Sep 17 00:00:00 2001
From: Sam Larsen <slarsen@meta.com>
Date: Wed, 5 Jun 2024 17:04:21 -0700
Subject: [PATCH] [inductor] Enable subprocess-based parallel compile as the
 default (#126817)

Differential Revision: [D58239826](https://our.internmc.facebook.com/intern/diff/D58239826)
Pull Request resolved: https://github.com/pytorch/pytorch/pull/126817
Approved by: https://github.com/eellison
ghstack dependencies: #128037, #128086
---
 torch/_inductor/config.py | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/torch/_inductor/config.py b/torch/_inductor/config.py
index b8ff5ae5a6c..dbaa528cd3e 100644
--- a/torch/_inductor/config.py
+++ b/torch/_inductor/config.py
@@ -387,7 +387,9 @@ developer_warnings = is_fbcode() or is_nightly_or_source
 # The multiprocessing start method to use for inductor workers in the codecache.
 # "subprocess", "fork", or "spawn"
 def decide_worker_start_method():
-    start_method = os.environ.get("TORCHINDUCTOR_WORKER_START", "fork")
+    start_method = os.environ.get(
+        "TORCHINDUCTOR_WORKER_START", "fork" if is_fbcode() else "subprocess"
+    )
     assert start_method in [
         "subprocess",
         "fork",