Concurrent file write

Question

how to write to a text file that can be accessed by multiple sources (possibly in a concurrent way) ensuring that no write operation gets lost?

Like, if two different processes are writing in the same moment to the file, this can lead to problems. The simples solution (not very fast and not very elegant) would be locking the file while beginning the process (create a .lock file or similar) and release it (delete the lock) while the writing is done.

When beginning to write, i would check if the .lock file exists and delay the writing till the file is released.

What is the recommended pattern to follow for this kind of situation?

Thanks

EDIT I mean processes, like different programs from different clients, different users and so on, not threads within the same program

Answer 1

Consider using a simple database. You will get all this built-in safety relatively easy.

Answer 2

The fastest way of synchronizing access between processes is to use Mutexes / Semaphores. This thread answers how to use them, to simulate read-writer lock pattern: Is there a global named reader/writer lock?