Multi processes read&write one file

Question

I have a txt file ABC.txt which will be read and wrote by multi processes. So when one process is reading from or writing to file ABC.txt, file ABC.txt must be locked so tha

Answer 1

Your solution is error prone. You've basically implemented double-checked locking (http://en.wikipedia.org/wiki/Double-checked_locking) which can be very unsafe.

A better solution would be to either introduce thread isolation, whereby only one thread ever accesses the file and does so by reading from a queue upon which requests to read or write are placed by other threads (and of course the queue is protected by mutually exclusive access by threads) or where the threads synchronize themselves either by synchronization devices (lock sections, mutices, whatever) or by using some other file access logic (for example, System.IO.FileShare came up in a few reponses here.)