Can you describe the principle of lock-free operation?

The main principle of lock-free algorithms is that, during parallel access to data, at least one thread can always complete its operation within a finite number of steps, regardless of the activity of other threads. This is achieved through the use of atomic operations such as Compare-And-Swap (CAS), Fetch-And-Add (FAA), and others provided by the processor.

Differences from locks:

Feature	Lock-based (with locks)	Lock-free (without locks)
Progress	Thread may be blocked	At least one thread makes progress
Deadlock	Possible	Impossible
Scheduler necessity	High	Less
Implementation complexity	Relatively simpler for simple cases	Higher, requires careful design

Applicability:

Lock-free data structures and algorithms are often used in high-load systems where minimizing delays and preventing deadlocks are critically important:

• Implementation of communication channels
• Lock-free queues and stacks
• Shared memory access

Example of CAS usage:

// Atomically replace the value of 'value' with 'new_value' if the current value equals 'old_value'.
// Returns true if the replacement occurred, false otherwise.
atomic.CompareAndSwapInt64(&value, old_value, new_value)

Lock-free complexities:

Developing lock-free algorithms is more complex due to the need to carefully consider thread interactions and the use of atomic operations. Problems such as the ABA problem may arise, requiring additional mechanisms like double-word CAS.