How can I synchronize mutlipe read/single write on a file available on a shared folder ?

See: http://www.boost.org/doc/libs/1_39_0/doc/html/interprocess/synchronization_m... But you should be really careful with API is used for file locking. I mean if you run on Linux you should be sure you are using fcntl and you do not share locks between threads etc... See section "Caution: Synchronization limitations"

The multiple read/write need to be synchronized b/w different processes running on different machine.

But generally speaking this is **bad idea**, shared file systems are not designed for IPC... Locks over shared file systems tend to be unreliable and tricky... So be very careful with it. Artyom