From a892b111a8e840f664cc9058a264df633324f19b Mon Sep 17 00:00:00 2001
From: pepijn <pepijn@huggingface.co>
Date: Thu, 16 Jul 2026 14:24:48 +0000
Subject: [PATCH] fix: use configured multiprocessing context for eval

Prevent evaluation workers from forking memory-heavy distributed training ranks and exhausting host RAM.

Co-authored-by: Cursor <cursoragent@cursor.com>
---
 src/lerobot/scripts/lerobot_train.py | 1 +
 1 file changed, 1 insertion(+)

diff --git a/src/lerobot/scripts/lerobot_train.py b/src/lerobot/scripts/lerobot_train.py
index 1d54af604..f7a4b033a 100644
--- a/src/lerobot/scripts/lerobot_train.py
+++ b/src/lerobot/scripts/lerobot_train.py
@@ -538,6 +538,7 @@ def train(cfg: TrainPipelineConfig, accelerator: "Accelerator | None" = None):
             collate_fn=eval_collate_fn,
             prefetch_factor=cfg.prefetch_factor if cfg.num_workers > 0 else None,
             persistent_workers=cfg.persistent_workers and cfg.num_workers > 0,
+            multiprocessing_context=mp_context if cfg.num_workers > 0 else None,
         )
 
     # Prepare everything with accelerator