Millistel tingimustel copy-on-write mehhanism lõpetab andmete koopiate tegemise tõhusalt vältimise?

The copy-on-write (COW) mechanism stops effectively preventing data copying when a modification occurs to a shared resource. Initially, multiple processes or threads can share the same memory block (e.g., a page), but when attempting to write to this block, a real copy of the data is made so that changes do not affect other owners.

Thus, the conditions under which COW loses efficiency are:

• Frequent writes or modifications of data leading to copying.
• A large number of processes actively changing data.
• If the data is initially unique and cannot be shared.

For example, if you have a shared array and several threads read it, no copying occurs. But as soon as one thread tries to modify an element of the array, a copy of that memory block is made, reducing the advantages of COW.