You are right.  I misread that totally.  Thanks!

 

John

    John Souvestre - New Orleans LA

 

From: Matt Harden [mailto:matt.har...@gmail.com] 
Sent: 2016 October 12, Wed 20:03
To: Minglangjun Li; John Souvestre
Cc: golang-nuts
Subject: Re: [go-nuts] infinite loop makes program stuck

 

On Wed, Oct 12, 2016 at 1:33 AM Minglangjun Li <liminglang...@gmail.com> wrote:

On Wed, Oct 12, 2016 at 11:53 AM, Jesse McNelis <jes...@jessta.id.au> wrote:

If you have multiple CPUs (and the Go memory model assumes that you
always can) they won't even write updated values from their cache out
to main memory until they hit a lock.
The reading CPU has read a value from main memory and put it in it's
cache, it assumes that value won't change in main memory unless it
hits a lock of it's own.

If you don't lock then both CPUs will just sit in their own little
world updating and reading values in their own caches and are never
aware of each other.

 

Thanks Jesse. Good to know that. 

 

On Wed, Oct 12, 2016 at 3:26 PM, John Souvestre <j...@souvestre.com> wrote:

I see that others have already addressed the locking issued, but I noticed 
something else.  I don’t understand why you are using “select”.  With only one 
case, I think that it’s normally going to fail and exit the select block, then 
loop due to the “for”.  This will make it run constantly.

 

That's not true. One of the select cases has to be satisfied; there is no 
failure. If there were a default case, that would be selected if no other case 
is ready. Without a default case, the select will block until one of the cases 
is ready. A single-case select can be replaced with a single send statement or 
receiving into a variable.

 

If you get rid of the “select” then the loop will block until something comes 
in from the channel. 

 

John

    John Souvestre - New Orleans LA

 

Please forgive me for that. I haven't been familiar with Go.

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