From 018fbc32233ea7d4b7e22430465077f08826bb95 Mon Sep 17 00:00:00 2001
From: Matija Kecman <matijak@google.com>
Date: Thu, 11 Jun 2026 06:11:37 -0700
Subject: [PATCH] Release GIL in native viewer.

Adds py::gil_scoped_release no_gil; to mujoco::studio::Viewer methods to release the Python GIL during C++ execution.

PiperOrigin-RevId: 930482271
Change-Id: I590794109418516ec5d9e8b536085560a1d36314
---
 python/mujoco/experimental/studio/native_viewer.cc | 11 ++++++++++-
 1 file changed, 10 insertions(+), 1 deletion(-)

diff --git a/python/mujoco/experimental/studio/native_viewer.cc b/python/mujoco/experimental/studio/native_viewer.cc
index 3cc587d4..a0558bdb 100644
--- a/python/mujoco/experimental/studio/native_viewer.cc
+++ b/python/mujoco/experimental/studio/native_viewer.cc
@@ -72,6 +72,7 @@ class Viewer {
  public:
   Viewer(const std::string& title, int width, int height,
          std::string graphics_mode_str) {
+    py::gil_scoped_release no_gil;
     // Register resource providers for font and filament assets.
     mjpResourceProvider resource_provider;
     mjp_defaultResourceProvider(&resource_provider);
@@ -113,16 +114,19 @@ class Viewer {
   }
 
   void InitRenderer(const mujoco::python::MjModelWrapper& model) {
+    py::gil_scoped_release no_gil;
     renderer_->Init(model.get());
   }
 
   bool NewFrame() {
+    py::gil_scoped_release no_gil;
     const mujoco::platform::Window::Status status = window_->NewFrame();
     return status == mujoco::platform::Window::Status::kRunning;
   }
 
   intptr_t UploadImage(intptr_t tex_id, const std::string img, int width,
                        int height, int bpp) {
+    py::gil_scoped_release no_gil;
     return renderer_->UploadImage(tex_id, (const std::byte*)img.data(), width,
                                   height, bpp);
   }
@@ -131,6 +135,7 @@ class Viewer {
                       mujoco::python::MjDataWrapper& data,
                       mujoco::python::MjvCameraWrapper& cam, int width,
                       int height, int tex_id) {
+    py::gil_scoped_release no_gil;
     const int bytes_per_pixel = 3;
     std::vector<std::byte> bytes(width * height * bytes_per_pixel);
     renderer_->RenderToTexture(model.get(), data.get(), cam.get(), width,
@@ -139,7 +144,9 @@ class Viewer {
                                   bytes_per_pixel);
   }
 
-  std::string GetDropFile() { return window_->GetDropFile(); }
+  std::string GetDropFile() {
+    return window_->GetDropFile();
+  }
 
   void Present(const mujoco::python::MjModelWrapper& model,
                mujoco::python::MjDataWrapper& data,
@@ -147,6 +154,8 @@ class Viewer {
                mujoco::python::MjvCameraWrapper& camera,
                mujoco::python::MjvOptionWrapper& vis_options,
                const std::vector<uint8_t>& render_flags) {
+    py::gil_scoped_release no_gil;
+
     const float width = window_->GetWidth();
     const float height = window_->GetHeight();
     const float scale = window_->GetScale();