Sorry, my last sentence should read " In this case,
is it possible for the program to output any value other than '6' for '*n'?"
Basically I declare n as an int*, and I allocate memory for *n, assign a value
to *n, and send the pointer n.
int *n = new int; *n = 4; *n += 2; zmq_socket.send(&n, sizeof(n));
So the pointer value is valid when sending actually takes place.
________________________________
From: Pieter Hintjens <[email protected]>
To: Kah-Chan Low <[email protected]>; ZeroMQ development list
<[email protected]>
Sent: Wednesday, November 28, 2012 11:22 PM
Subject: Re: [zeromq-dev] inproc: passing an object pointer between threads
causing datarace?? (3.2.2 stable release)
On Tue, Nov 27, 2012 at 10:23 PM, Kah-Chan Low <[email protected]> wrote:
> 1. I don't understand the error message above: how does accessing the value
> of variable n have anything to do with the internals of ZMQ?
It doesn't, as far as I can see.
> 2. Is it possible for the compiler to rearrange the machine instructions
> such that the assignment of value of n (i.e. *n=4; *n += 2;) occurs after
> the message has been sent and received on the other thread? In this case,
> is it possible for the program to output any value other than '6' for 'n'?
That's very doubtful. However are you not declaring n on the stack?
Meaning, it will not be valid when the send actually happens.
-Pieter
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