Subj : Memory visibility and synchronization using pipes
To   : comp.programming.threads
From : Marcin 'Qrczak' Kowalczyk
Date : Sat Jan 15 2005 12:10 pm

Let's say thread A does this:
- changes a variable
- writes to a pipe
and thread B does this:
- waits until poll() says the pipe can be read
- accesses the variable
(the pipe is used only for this synchronization).

Is it safe, or the change to the variable may not be seen by the other
thread? I guess write() and poll() are not memory barriers and this is
unsafe. If so, how to fix it in the simplest way?

I'm using a pipe because thread B uses poll() on other descriptors at
the same time.

-- 
   __("<         Marcin Kowalczyk
   \__/       qrczak@knm.org.pl
    ^^     http://qrnik.knm.org.pl/~qrczak/

.