Re: [Help-smalltalk] non-blocking pipe read issue

[Paolo Bonzini]

On 02/02/2012 01:02 PM, Derek Zhou wrote:
> Although it does a second poll after the sig handler setup trying to catch
> this possibility, the data could still come in after the second poll but
> before the _gst_sync_wait. The sig handler will trigger but it does not
> prevent the process going to sleep.
>
>  From the look of it the problem is not limited to pipes, the same could
> happen to sockets as well.
>
> Possible fixes:
> * block SIGIO until the process is really asleep in an atomic operation.
> However I don't know how.

It must be more subtle than that.

The SIGIO will not be processed immediately; it will be processed before 
executing the next bytecode.  This should close the race window with the 
update of the list.  In fact, the second poll could be removed, I think.

Paolo