Implement threading for island constraint solving.

Humanoids22 No threads:
 Benchmark Execution Time: 9.475905812s

Humanoids22 with 10 Threads:
 Benchmark Execution Time: 4.871352s

PiperOrigin-RevId: 571214307
Change-Id: I1f4f2c761b4ae6bc8fac1f28c6c695f6c499f339

doc/APIreference/functions.rst

@@ -3446,6 +3446,15 @@ mju_threadPoolCreate
 
 Create a thread pool with the specified number of threads running.
 
+.. _mju_bindThreadPool:
+
+mju_bindThreadPool
+~~~~~~~~~~~~~~~~~~
+
+.. mujoco-include:: mju_bindThreadPool
+
+Adds a thread pool to :ref:`mjData` and configures it for multi-threaded use.
+
 .. _mju_threadPoolEnqueue:
 
 mju_threadPoolEnqueue

doc/changelog.rst

@@ -122,11 +122,13 @@ General
       attributes are specified. See the following
       `example model <https://github.com/deepmind/mujoco/blob/main/test/engine/testdata/vis_visualize/frustum.xml>`__.
     - Note that these attributes only take effect for offline rendering and do not affect interactive visualisation.
-
+22. Added multi-threaded constraint solving via :ref:`mj_island` and :ref:`mjThreadPool` to :ref:`testspeed<saTestspeed>`
+    exposed via npoolthread flag. The `22 humanoids <https://github.com/deepmind/mujoco/blob/main/model/humanoid/22_humanoids.xml>`__
+    model shows a 3x speedup compared to the single threaded simulation.
 Python bindings
 ^^^^^^^^^^^^^^^
 
-22. Fixed `#870 <https://github.com/google-deepmind/mujoco/issues/870>`__ where calling ``update_scene`` with an invalid
+23. Fixed `#870 <https://github.com/google-deepmind/mujoco/issues/870>`__ where calling ``update_scene`` with an invalid
     camera name used the default camera.
 
 Simulate
@@ -136,18 +138,18 @@ Simulate
    :align: right
    :width: 240px
 
-23. Added **state history** mechanism to :ref:`simulate<saSimulate>` and the managed
+24. Added **state history** mechanism to :ref:`simulate<saSimulate>` and the managed
     :ref:`Python viewer<PyViewerManaged>`. State history can be viewed by scrubbing the History slider and (more
     precisely) with the left and right arrow keys. See screen capture:
 
-24. The ``LOADING...`` label is now shown correctly.
+25. The ``LOADING...`` label is now shown correctly.
     `Contribution <https://github.com/google-deepmind/mujoco/pull/1070>`__ by
     `Levi Burner <https://github.com/aftersomemath>`__.
 
 Bug fixes
 ^^^^^^^^^
 
-25. Fixed a bug that was causing :ref:`geom margin<body-geom-margin>` to be ignored during the construction of
+26. Fixed a bug that was causing :ref:`geom margin<body-geom-margin>` to be ignored during the construction of
     midphase collision trees.
 
 Version 2.3.7 (July 20, 2023)

doc/includes/references.h

@@ -2613,6 +2613,7 @@ int mjp_resourceProviderCount(void);
 const mjpResourceProvider* mjp_getResourceProvider(const char* resource_name);
 const mjpResourceProvider* mjp_getResourceProviderAtSlot(int slot);
 mjThreadPool* mju_threadPoolCreate(size_t number_of_threads);
+void mju_bindThreadPool(mjData* d, void* thread_pool);
 void mju_threadPoolEnqueue(mjThreadPool* thread_pool, mjTask* task);
 void mju_threadPoolDestroy(mjThreadPool* thread_pool);
 void mju_defaultTask(mjTask* task);