Re: [HACKERS] Clarifying "server starting" messaging in pg_ctl start without --wait

[Ryan Murphy]

> Making --wait the default may or may not be sensible -- I'm not sure
> -- but removing --no-wait is clearly a bad idea, and we shouldn't do
> it.  The fact that the problems created by removing it might be
> solvable doesn't mean that it's a good idea to create them in the
> first place.
>
>
>
I agree with Robert - pg_ctl is no doubt used in all kinds of scripts that
would then have to change.
It may make sense to have --wait be the default though - certainly less
confusing to new users!

Re: [HACKERS] Clarifying "server starting" messaging in pg_ctl start without --wait

[Robert Haas]

On Fri, Dec 23, 2016 at 7:25 PM, Jim Nasby  wrote:
> On 12/23/16 6:10 PM, Tom Lane wrote:
>> Michael Paquier  writes:
>>> Is there still a use case for --no-wait in the real world?
>>
>> Sure.  Most system startup scripts aren't going to want to wait.
>> If we take it out those people will go back to starting the postmaster
>> by hand.
>
> Presumably they could just background it... since it's not going to be
> long-lived it's presumably not that big a deal. Though, seems like many
> startup scripts like to make sure what they're starting is actually working.

Making --wait the default may or may not be sensible -- I'm not sure
-- but removing --no-wait is clearly a bad idea, and we shouldn't do
it.  The fact that the problems created by removing it might be
solvable doesn't mean that it's a good idea to create them in the
first place.

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Re: [HACKERS] Clarifying "server starting" messaging in pg_ctl start without --wait

[Jim Nasby]

On 12/23/16 6:10 PM, Tom Lane wrote:

Michael Paquier  writes:

Is there still a use case for --no-wait in the real world?


Sure.  Most system startup scripts aren't going to want to wait.
If we take it out those people will go back to starting the postmaster
by hand.


Presumably they could just background it... since it's not going to be 
long-lived it's presumably not that big a deal. Though, seems like many 
startup scripts like to make sure what they're starting is actually working.


What might be interesting is a mode that waited for everything but 
recovery so at least you know the config is valid, the port is 
available, etc. That would be much harder to handle externally.



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Re: [HACKERS] Clarifying "server starting" messaging in pg_ctl start without --wait

[Tom Lane]

Michael Paquier  writes:
> Is there still a use case for --no-wait in the real world?

Sure.  Most system startup scripts aren't going to want to wait.
If we take it out those people will go back to starting the postmaster
by hand.

regards, tom lane


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Re: [HACKERS] Clarifying "server starting" messaging in pg_ctl start without --wait

[Michael Paquier]

On Fri, Dec 23, 2016 at 10:47 PM, Peter Eisentraut
 wrote:
> On 12/20/16 3:43 PM, Peter Eisentraut wrote:
>> On 12/20/16 3:31 PM, Ryan Murphy wrote:
>>> I'm concerned some new users may not understand this behavior of pg_ctl,
>>> so I wanted to suggest that we add some additional messaging after
>>> "server starting" - something like:
>>>
>>> $ pg_ctl -D datadir -l logfile start
>>> server starting
>>> (to wait for confirmation that server actually started, try pg_ctl again
>>> with --wait)
>>
>> Maybe the fix is to make --wait the default?
>
> Here is a patch for that.

Is there still a use case for --no-wait in the real world? Why not
simply ripping it out?
-- 
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Re: [HACKERS] Clarifying "server starting" messaging in pg_ctl start without --wait

[Peter Eisentraut]

On 12/20/16 3:43 PM, Peter Eisentraut wrote:
> On 12/20/16 3:31 PM, Ryan Murphy wrote:
>> I'm concerned some new users may not understand this behavior of pg_ctl,
>> so I wanted to suggest that we add some additional messaging after
>> "server starting" - something like:
>>
>> $ pg_ctl -D datadir -l logfile start
>> server starting
>> (to wait for confirmation that server actually started, try pg_ctl again
>> with --wait)
> 
> Maybe the fix is to make --wait the default?

Here is a patch for that.

-- 
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PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services
>From 400c5445381596c1b5b5083a56d130498ade421b Mon Sep 17 00:00:00 2001
From: Peter Eisentraut 
Date: Fri, 23 Dec 2016 12:00:00 -0500
Subject: [PATCH] pg_ctl: Change default to wait for all actions

---
 doc/src/sgml/ref/pg_ctl-ref.sgml | 36 +++-
 src/bin/pg_ctl/pg_ctl.c  | 15 ++-
 2 files changed, 21 insertions(+), 30 deletions(-)

diff --git a/doc/src/sgml/ref/pg_ctl-ref.sgml b/doc/src/sgml/ref/pg_ctl-ref.sgml
index 5fb6898699..7587355164 100644
--- a/doc/src/sgml/ref/pg_ctl-ref.sgml
+++ b/doc/src/sgml/ref/pg_ctl-ref.sgml
@@ -31,7 +31,7 @@
   
pg_ctl
start
-   -w
+   -W
-t seconds
-s
-D datadir
@@ -60,7 +60,7 @@
   
pg_ctl
restart
-   -w
+   -W
-t seconds
-s
-D datadir
@@ -91,7 +91,7 @@
   
pg_ctl
promote
-   -w
+   -W
-t seconds
-s
-D datadir
@@ -117,7 +117,7 @@
d[emand]
  

-   -w
+   -W
-t seconds
-s
-o options
@@ -391,17 +391,7 @@ Options
 Wait for an operation to complete.  This is supported for the
 modes start, stop,
 restart, promote,
-and register.
-   
-
-   
-Waiting is the default option for shutdowns, but not startups,
-restarts, or promotions.  This is mainly for historical reasons; the
-waiting option is almost always preferable.  If waiting is not
-selected, the requested action is triggered, but there is no feedback
-about its success.  In that case, the server log file or an external
-monitoring system would have to be used to check the progress and
-success of the operation.
+and register, and is the default for those modes.

 

@@ -424,6 +414,18 @@ Options
 Do not wait for an operation to complete.  This is the opposite of the
 option -w.

+
+   
+If waiting is disabled, the requested action is triggered, but there
+is no feedback about its success.  In that case, the server log file
+or an external monitoring system would have to be used to check the
+progress and success of the operation.
+   
+
+   
+In prior releases of PostgreSQL, this was the default except for
+the stop mode.
+   
   
  
 
@@ -593,7 +595,7 @@ Starting the Server
 To start the server, waiting until the server is
 accepting connections:
 
-$ pg_ctl -w start
+$ pg_ctl start
 

 
@@ -637,7 +639,7 @@ Restarting the Server
 To restart the server,
 waiting for it to shut down and restart:
 
-$ pg_ctl -w restart
+$ pg_ctl restart
 

 
diff --git a/src/bin/pg_ctl/pg_ctl.c b/src/bin/pg_ctl/pg_ctl.c
index 4b476022c0..91d4e0d080 100644
--- a/src/bin/pg_ctl/pg_ctl.c
+++ b/src/bin/pg_ctl/pg_ctl.c
@@ -71,8 +71,7 @@ typedef enum
 
 #define DEFAULT_WAIT	60
 
-static bool do_wait = false;
-static bool wait_set = false;
+static bool do_wait = true;
 static int	wait_seconds = DEFAULT_WAIT;
 static bool wait_seconds_arg = false;
 static bool silent_mode = false;
@@ -1959,7 +1958,7 @@ do_help(void)
 	printf(_("  -s, --silent   only print errors, no informational messages\n"));
 	printf(_("  -t, --timeout=SECS seconds to wait when using -w option\n"));
 	printf(_("  -V, --version  output version information, then exit\n"));
-	printf(_("  -w, --wait wait until operation completes\n"));
+	printf(_("  -w, --wait wait until operation completes (default)\n"));
 	printf(_("  -W, --no-wait  do not wait until operation completes\n"));
 	printf(_("  -?, --help show this help, then exit\n"));
 	printf(_("(The default is to wait for shutdown, but not for start or restart.)\n\n"));
@@ -2323,11 +2322,9 @@ main(int argc, char **argv)
 	break;
 case 'w':
 	do_wait = true;
-	wait_set = true;
 	break;
 case 'W':
 	do_wait = false;
-	wait_set = true;
 	break;
 case 'c':
 	allow_core_files = true;
@@ -2423,14 +2420,6 @@ main(int argc, char **argv)
 		exit(1);
 	}
 
-	if (!wait_set)
-	{
-		if (ctl_command == STOP_COMMAND)
-			do_wait = true;
-		else
-			do_wait = false;
-	}
-
 	if (ctl_command == RELOAD_COMMAND)
 	{
 		sig = SIGHUP;
-- 
2.11.0


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Re: [HACKERS] Clarifying "server starting" messaging in pg_ctl start without --wait

[Peter Eisentraut]

On 12/20/16 3:49 PM, Tom Lane wrote:
> Peter Eisentraut  writes:
>> Maybe the fix is to make --wait the default?
> I was wondering about that too ... does anyone remember the rationale
> for the current behavior?

Probably because that didn't work reliably before pg_ctl learned how to
get the right port number and PQping() and such things.

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Re: [HACKERS] Clarifying "server starting" messaging in pg_ctl start without --wait

[David G. Johnston]

On Tue, Dec 20, 2016 at 1:49 PM, Tom Lane  wrote:

> Peter Eisentraut  writes:
> > Maybe the fix is to make --wait the default?
>
> I was wondering about that too ... does anyone remember the rationale
> for the current behavior?  But the message for the non-wait case seems
> like it could stand to be improved independently of that.
>

​Not totally independent.​

If the default is changed to --wait then the message can be written
assuming the user understands what "--no-wait" does; but if the default is
left "--no-wait" then cluing the user into the asynchronous behavior and
telling them how to get the more expected synchronous behavior would be
helpful.

David J.
​

Re: [HACKERS] Clarifying "server starting" messaging in pg_ctl start without --wait

[Alvaro Herrera]

Tom Lane wrote:
> Ryan Murphy  writes:
> > I'm concerned some new users may not understand this behavior of pg_ctl, so
> > I wanted to suggest that we add some additional messaging after "server
> > starting" - something like:
> 
> > $ pg_ctl -D datadir -l logfile start
> > server starting
> > (to wait for confirmation that server actually started, try pg_ctl again
> > with --wait)
> 
> That seems annoyingly verbose and nanny-ish.  Perhaps we could get the
> point across like this:
> 
> $ pg_ctl -D datadir -l logfile start
> requested server to start

+1, but also +1 to making --wait the default.  Extra points if systemd
start scripts are broken by the change ;-)

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Re: [HACKERS] Clarifying "server starting" messaging in pg_ctl start without --wait

[Tom Lane]

Peter Eisentraut  writes:
> Maybe the fix is to make --wait the default?

I was wondering about that too ... does anyone remember the rationale
for the current behavior?  But the message for the non-wait case seems
like it could stand to be improved independently of that.

regards, tom lane


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Re: [HACKERS] Clarifying "server starting" messaging in pg_ctl start without --wait

[Tom Lane]

Ryan Murphy  writes:
> I'm concerned some new users may not understand this behavior of pg_ctl, so
> I wanted to suggest that we add some additional messaging after "server
> starting" - something like:

> $ pg_ctl -D datadir -l logfile start
> server starting
> (to wait for confirmation that server actually started, try pg_ctl again
> with --wait)

That seems annoyingly verbose and nanny-ish.  Perhaps we could get the
point across like this:

$ pg_ctl -D datadir -l logfile start
requested server to start
$

regards, tom lane


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Re: [HACKERS] Clarifying "server starting" messaging in pg_ctl start without --wait

[David Fetter]

On Tue, Dec 20, 2016 at 03:43:11PM -0500, Peter Eisentraut wrote:
> On 12/20/16 3:31 PM, Ryan Murphy wrote:
> > I'm concerned some new users may not understand this behavior of pg_ctl,
> > so I wanted to suggest that we add some additional messaging after
> > "server starting" - something like:
> > 
> > $ pg_ctl -D datadir -l logfile start
> > server starting
> > (to wait for confirmation that server actually started, try pg_ctl again
> > with --wait)
> 
> Maybe the fix is to make --wait the default?

+1

It's not super useful to have the prompt return while the server is
still starting up.

Best,
David.
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Re: [HACKERS] Clarifying "server starting" messaging in pg_ctl start without --wait

[Peter Eisentraut]

On 12/20/16 3:31 PM, Ryan Murphy wrote:
> I'm concerned some new users may not understand this behavior of pg_ctl,
> so I wanted to suggest that we add some additional messaging after
> "server starting" - something like:
> 
> $ pg_ctl -D datadir -l logfile start
> server starting
> (to wait for confirmation that server actually started, try pg_ctl again
> with --wait)

Maybe the fix is to make --wait the default?

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[HACKERS] Clarifying "server starting" messaging in pg_ctl start without --wait

[Ryan Murphy]

Hi Postgres Devs,

I had a suggestion regarding the output pg_ctl gives when you use it to
start the postgres server.  At first I was going to write a patch, but then
I decided to just ask you guys first to see what you think.

I had an issue earlier where I was trying to upgrade my postgres database
to a new major version and incidentally a new pg_catalog version, and
therefore the new code could no longer run the existing data directory
without pg_upgrade or pg_dump (I ended up needing pg_dump).  Initially I
was very confused because I tried running "pg_ctl -D datadir -l logfile
start" like normal, and it just said "server starting", yet the server was
not starting.  It took me a while to realize that I needed to use the
"--wait" / "-w" option to actually wait and test whether the server was
really starting, at which point it told me there was a problem and to check
the log.

I'm concerned some new users may not understand this behavior of pg_ctl, so
I wanted to suggest that we add some additional messaging after "server
starting" - something like:

$ pg_ctl -D datadir -l logfile start
server starting
(to wait for confirmation that server actually started, try pg_ctl again
with --wait)

What do you guys think?  Is it important to keep pg_ctl output more terse
than this?  I do think something like this could help new users avoid
frustration.

I'm happy to write a patch for this if it's helpful, though it's such a
simple change that if one of the core devs wants this s/he can probably
more easily just add it themselves.

Cheers,
Ryan