Saran Tunyasuvunakool
a07ae6f849
Introduce a new header `gil.h` defining `MutexLockIfGilDisabled` to support thread-safety in both standard and free-threaded CPython builds. Protect critical shared states and registries: - Guard global Python callback pointers in `callbacks.cc` using a mutex. Move `gil_scoped_acquire` into local blocks around refcount modifications to prevent `longjmp` from bypassing destructors. - Protect raw pointer maps in `structs_wrappers.cc` with static mutexes. - Replace TOCTOU race in `mjcb_time` initialization with thread-safe `std::call_once`. - Add synchronization to lazy indexer array cache initialization in `indexers.cc` and `indexer_xmacro.h`. - Protect vector mutations in `StructListBase::PopulateUpTo` in `structs.h` with a mutex. - Revert unnecessary atomic changes to threadpool counters. - Declare free-threading compatibility by passing `pybind11::mod_gil_not_used()` to all extension modules. Fixes #3259 Fixes #3256 Fixes #2978 PiperOrigin-RevId: 941101502 Change-Id: Iec4ce58afcbc75d4b0be6a9a21fc8a47854242e3
63 lines
2.0 KiB
C++
63 lines
2.0 KiB
C++
// Copyright 2026 DeepMind Technologies Limited
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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#ifndef MUJOCO_PYTHON_GIL_H_
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#define MUJOCO_PYTHON_GIL_H_
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#include <mutex>
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namespace mujoco::python {
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// A scoped lock that acquires a std::mutex in free-threaded Python builds
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// (Py_GIL_DISABLED) and does nothing in standard GIL builds.
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//
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// In standard builds the GIL already serializes access to Python state, so
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// adding a C++ mutex would introduce unnecessary overhead and deadlock risk
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// (two locks held simultaneously). In free-threaded builds the GIL is absent,
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// so an explicit mutex is required to protect shared mutable C++ state.
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//
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// Usage:
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// static std::mutex my_mutex;
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// {
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// MutexLockIfGilDisabled lock(my_mutex);
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// // ... access shared state ...
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// }
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#ifdef Py_GIL_DISABLED
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class MutexLockIfGilDisabled {
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public:
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explicit MutexLockIfGilDisabled(std::mutex& mtx) : lock_(mtx) {}
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MutexLockIfGilDisabled(const MutexLockIfGilDisabled&) = delete;
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MutexLockIfGilDisabled& operator=(const MutexLockIfGilDisabled&) = delete;
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private:
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std::lock_guard<std::mutex> lock_;
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};
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#else
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class MutexLockIfGilDisabled {
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public:
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explicit MutexLockIfGilDisabled(std::mutex& /*unused*/) {}
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MutexLockIfGilDisabled(const MutexLockIfGilDisabled&) = delete;
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MutexLockIfGilDisabled& operator=(const MutexLockIfGilDisabled&) = delete;
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};
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#endif
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inline std::mutex& GetCallbackMutex() {
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static std::mutex mtx;
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return mtx;
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}
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} // namespace mujoco::python
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#endif // MUJOCO_PYTHON_GIL_H_
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