The core and the headless tools no longer use mutexes, condition variables,
spinlocks, std::atomic, std::thread or volatile flags. Threads hand off through
libretro-common's retro_atomic and rthreads plus a few small pieces on top of
them in Common/Thread: Thread, MpscQueue, EventCounter, ParkingLot waits and
ReaderGate. Every wait blocks until it's woken; nothing polls on a timer.
State that only one thread touches just loses its lock. The PSP filesystem,
sceIo and the savedata dialog now belong to the emulation thread: async reads
and writes run when they're queued and complete later in emulated time, and
the IO and savedata threads are gone. The friend finder only talks to the
adhoc server and hands what it gets to the emulation thread. GPU init always
runs on the thread that starts the game.
The Vulkan render and compile queues, pipeline and render pass caches, delete
list and SPIR-V cache, the GL render queue, the software renderer's jit caches,
the file loader caches, the web debugger, UPnP, input, savestates, logging and
the GE debugger all hand off through queues and atomics. The IR jit's spinning
profiler thread goes.
A CPU thread with nothing to run now sleeps until work is queued instead of
spinning. Headless with --debugger waits for a client while stopped, and ends
the run once every client that connected has left. Web server shutdown keeps
servicing the CPU queue until the server has finished.
- ~ThreadManager() never stopped worker threads before freeing the
global context. If Teardown() wasn't reached before process exit
(e.g. an early return between Init() and a caller's shutdown path),
the still-running threads kept touching freed mutexes/queues/condvars,
causing intermittent crashes on exit. The destructor now tears down
if still initialized.
- Teardown() silently leaked any non-cancellable task still sitting in
a queue (global or per-thread) at shutdown time - such tasks were
never run nor released, since nothing drains those queues once the
worker threads have been marked cancelled/joined. Now every queued
task is properly cancelled-or-warned and released.
- Added an assert against a divide-by-zero in EnqueueTask's round-robin
fallback, which would trigger if Init() were ever called with zero
compute threads.
- Removed Task::id()/Kind() and ThreadManager::TryCancelTask(), which
were unused dead code (TryCancelTask was a no-op with no callers).
- Fixed a stale comment on EnqueueTaskOnThread referencing a parameter
that doesn't exist, and an auto-typed ternary that misleadingly read
like a deque array copy (it's a pointer, not a copy).
Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01L4QAoxV2KY7ek4PcZw3WvY
Useful for things that should be run ASAP even if the threadpool is full,
at a small extra cost. (Not recommended for very small tasks).
Considering using this to resolve the deadlocks in #16802.
Moves ThreadPool teardown to retro_unload_game. Gives ThreadPool threads some breathing room to terminate before game load starts spamming it with tasks.
libretroadmin