Advanced Threads (Fork-Join)

When spawning threads inside a loop using `fork...join_none`, if the loop variable (e.g., `i`) is static (default in Verilog), all threads will see the FINAL value of `i` when they start.

Fix: Use `automatic` variables inside the loop to create a unique copy for each thread.

for (int i=0; i<3; i++) begin
    automatic int k = i; // CRITICAL
    fork
        $display("Thread %0d", k);
    join_none
end

• wait fork: Waits for ALL child processes spawned by the current process to complete properly.
• disable fork: Kills ALL active children of the current process immediately.

Assign names to the fork block, or wrap code in `begin...end` with names, and use `disable label_name`. However, usually `process` class is preferred for fine-grained control.