code review 5321058: spec: define that initialization is sequential

spec: define that initialization is sequential

This is true of the existing implementations, and I think
it is an important property to guarantee.

[rsc, 2011-10-27 01:14:24]

Hello golang-dev@googlegroups.com,

I'd like you to review this change to
https://go.googlecode.com/hg/

[r2, 2011-10-27 01:53:59]

they will run concurrently if you call them directly. it would be
folly to do so, but that unqualified "never" is too bold. also the
grammar is convoluted.


An <code>init</code> function may launch other goroutines, which can run
concurrently with the initialization code. However, initialization
always sequences
the <code>init</code> functions: it will not start the next
<code>init</code> until
the previous one has returned.

[rsc, 2011-10-27 01:58:40]

On Wed, Oct 26, 2011 at 18:53, Rob 'Commander' Pike <r@google.com> wrote:
> they will run concurrently if you call them directly. it would be
> folly to do so, but that unqualified "never" is too bold.

it is impossible to call an init function directly.

[borman, 2011-10-27 02:13:32]

recursive inits?  (sorry, I could not help myself :-)

On Wed, Oct 26, 2011 at 6:58 PM, Russ Cox <rsc@golang.org> wrote:

> On Wed, Oct 26, 2011 at 18:53, Rob 'Commander' Pike <r@google.com> wrote:
> > they will run concurrently if you call them directly. it would be
> > folly to do so, but that unqualified "never" is too bold.
>
> it is impossible to call an init function directly.
>

[rsc, 2011-10-27 02:37:06]

On Wed, Oct 26, 2011 at 19:13, Paul Borman <borman@google.com> wrote:
> recursive inits?  (sorry, I could not help myself :-)

i don't know what this means

[r2, 2011-10-27 03:07:34]

right. forgot that detail.

i still prefer my version; it's clearer than statements about concurrency.

-rob

[rsc, 2011-10-27 14:43:39]

PTAL.  I kept the first sentence to make clear that one
package init happens at a time.

Package initialization—variable initialization and the invocation of
init functions—happens in a single goroutine, sequentially, one
package at a time. An init function may launch other goroutines, which
can run concurrently with the initialization code. However,
initialization always sequences the init functions: it will not start
the next init until the previous one has returned.

[r, 2011-10-27 15:50:38]

LGTM

[rsc, 2011-10-27 19:22:54]

*** Submitted as http://code.google.com/p/go/source/detail?r=3f70682b9214 ***

spec: define that initialization is sequential

This is true of the existing implementations, and I think
it is an important property to guarantee.

R=golang-dev, r, borman, r
CC=golang-dev
http://codereview.appspot.com/5321058

[r, 2011-10-28 15:09:59]

LGTM