Peredvizhnikov Engine: Lock-free game engine written in C++20
I have an Actor framework which uses a vanilla std::deque for method pointers, and to add messages to the queue, the locking technique is a Benaphore (the original Futex, which uses an atomic and a locking primitive, with the twist that my locking primitive is a combo of spinlock/mutex based on retry count).  Nothing special. 
 Benchmarks show that very rarely does the message push function block, and the chance of an OS context switch is also very low, so even though occasionally we get a locked thread swapping out, it is so infrequent that it doesn't justify the lock-free algorithm cost.In a nutshell, non lock free queues are much faster than lock free queues, however you must be prepared to accept the very infrequent longer delay due to a context switch (where the lock is not available to anyone).  My benchmarks show that the price is acceptable since so much more performance is available with non lock free queues.  10 million messages per second per work thread can be queued on modern hardware.