Re: [HACKERS] Remove Windows crash dump support?

[Andres Freund]

On 2016-01-04 16:39:22 +0900, Michael Paquier wrote:
> So I think that it is still useful for debugging code
> paths running custom code, even if we consider Postgres as rock-solid
> on Windows.

Given the state of e.g. the socket using code for windows I personally
certainly don't consider it rock solid.

Either way, since there were a few people interested in keeping the
support, and nobody really had any arguments besids "seems unused" for
removing it, this seems like a pretty clear cut case.

Andres


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Re: [HACKERS] Remove Windows crash dump support?

[Michael Paquier]

On Fri, Dec 25, 2015 at 8:57 PM, Craig Ringer  wrote:
> On 25 December 2015 at 19:45, Michael Paquier 
> wrote:
>>
>> On Thu, Dec 24, 2015 at 5:57 PM, Dave Page  wrote:
>> > On Thu, Dec 24, 2015 at 2:14 AM, Craig Ringer 
>> > wrote:
>> >> On 22 December 2015 at 23:48, Alex Ignatov 
>> >> wrote:
>> >>
>> >>>
>> >>> I think that you can debug crash dump since windbg exists.
>> >>
>> >>
>> >> Nobody in their right mind uses windbg though. Visual Studio is really
>> >> where
>> >> it's at and the Express versions make it much more practical.
>>
>> Well, FWIW, I have been working lately on a bug hidden in a custom
>> background worker on Windows that crashed in some weird way with a
>> 0x00C5, and while I have a reproducible test case I have not yet
>> found the time to look at it yet but I would think that this is
>> generating a core dump, and that I will need to use windbg for that.
>> Hence count me on the -1 team.
>
>
> Huh?
>
> You can use VS Express to debug a core dump.  Per links upthread you can get
> the platform to generate core dumps for you. No windbg required.
>
> If you want to torture yourself using windbg go ahead, but it really isn't
> necessary, you can use a sane debugger.

Well, coming back to my story with the background worker I have been
debugging. Creating PGDATA/crashdumps has allowed me to easily get a
dump, and then I had a look at it using my Win7 workstation because VS
was not available in the server where the crash happened, which was a
2k12 server btw. So I think that it is still useful for debugging code
paths running custom code, even if we consider Postgres as rock-solid
on Windows.

In short, -1.
-- 
Michael


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Re: [HACKERS] Remove Windows crash dump support?

[Feng Tian]

On Wed, Dec 23, 2015 at 6:14 PM, Craig Ringer  wrote:

> On 22 December 2015 at 23:48, Alex Ignatov 
> wrote:
>
>
>> I think that you can debug crash dump since windbg exists.
>>
>
> Nobody in their right mind uses windbg though. Visual Studio is really
> where it's at and the Express versions make it much more practical.
>

Just FYI.  Most developers of MS server (OS/SQL Server) team use windbg.
Windbg was my only debugger when I worked there and I never used Visual
Studio.




>
> You can't even install Debugging Tools for Windows and Windbg standalone
> anymore.
>
>
>> Also I think that Postgres on Windows number  of instalations is so tiny
>> because people even today think that it is not so solid as unix version
>> thats why you think that nobody use your code ;).
>>
>
> I disagree. Windows Pg users are often at bigger companies and don't talk
> about PostgreSQL as much. Often for fear of reprisals from other database
> vendors they have ongoing relationships with.  At least that's been my
> experience and I'm sure EDB folks will concur.
>
>
>> Today if my memory serves me right this code can not deal with buffer
>> overflow. Am i right?
>>
>
> Stack overflow?
>
> No, it can't. The stack has to be somewhat sane.
>
>
>> May be we need to add this functionality instead of drop support of it
>> entirely
>>
>
> Why? I've never seen any sign anybody has used it, ever.
>
> --
>  Craig Ringer   http://www.2ndQuadrant.com/
>  PostgreSQL Development, 24x7 Support, Training & Services
>

Re: [HACKERS] Remove Windows crash dump support?

[Amit Kapila]

On Thu, Dec 24, 2015 at 7:48 AM, Craig Ringer  wrote:

> On 22 December 2015 at 23:46, Tom Lane  wrote:
>
>> > In which version(s) of Windows was this improvement added?
>
>
> Vista and Server 2008 (original, not R2).
>
>
> https://msdn.microsoft.com/en-us/library/windows/desktop/bb787181(v=vs.85).aspx
>
> Win7 and Server 2003 are already irrelevant now, and will be absurdly so
> by the time Pg 9.6 comes out.
>
>
Sure, but I think still there could be developers out there or some users
of PostgreSQL who will still be using some such systems.


> The windows feature works better than the in-application crash dump.
>

Have you used this feature of Windows and does it display the call stack
or the information better than what PostgreSQL already has, if you have
any saved dump, that others can also see, that might be useful?
Unfortunately, I am still using Win7, so not able to test using this
new feature.


With Regards,
Amit Kapila.
EnterpriseDB: http://www.enterprisedb.com

Re: [HACKERS] Remove Windows crash dump support?

[Craig Ringer]

On 25 December 2015 at 19:45, Michael Paquier 
wrote:

> On Thu, Dec 24, 2015 at 5:57 PM, Dave Page  wrote:
> > On Thu, Dec 24, 2015 at 2:14 AM, Craig Ringer 
> wrote:
> >> On 22 December 2015 at 23:48, Alex Ignatov 
> wrote:
> >>
> >>>
> >>> I think that you can debug crash dump since windbg exists.
> >>
> >>
> >> Nobody in their right mind uses windbg though. Visual Studio is really
> where
> >> it's at and the Express versions make it much more practical.
>
> Well, FWIW, I have been working lately on a bug hidden in a custom
> background worker on Windows that crashed in some weird way with a
> 0x00C5, and while I have a reproducible test case I have not yet
> found the time to look at it yet but I would think that this is
> generating a core dump, and that I will need to use windbg for that.
> Hence count me on the -1 team.
>

Huh?

You can use VS Express to debug a core dump.  Per links upthread you can
get the platform to generate core dumps for you. No windbg required.

If you want to torture yourself using windbg go ahead, but it really isn't
necessary, you can use a sane debugger.

-- 
 Craig Ringer   http://www.2ndQuadrant.com/
 PostgreSQL Development, 24x7 Support, Training & Services

Re: [HACKERS] Remove Windows crash dump support?

[Michael Paquier]

On Thu, Dec 24, 2015 at 5:57 PM, Dave Page  wrote:
> On Thu, Dec 24, 2015 at 2:14 AM, Craig Ringer  wrote:
>> On 22 December 2015 at 23:48, Alex Ignatov  wrote:
>>
>>>
>>> I think that you can debug crash dump since windbg exists.
>>
>>
>> Nobody in their right mind uses windbg though. Visual Studio is really where
>> it's at and the Express versions make it much more practical.

Well, FWIW, I have been working lately on a bug hidden in a custom
background worker on Windows that crashed in some weird way with a
0x00C5, and while I have a reproducible test case I have not yet
found the time to look at it yet but I would think that this is
generating a core dump, and that I will need to use windbg for that.
Hence count me on the -1 team.

>> You can't even install Debugging Tools for Windows and Windbg standalone
>> anymore.
>>
>>>
>>> Also I think that Postgres on Windows number  of instalations is so tiny
>>> because people even today think that it is not so solid as unix version
>>> thats why you think that nobody use your code ;).
>>
>>
>> I disagree. Windows Pg users are often at bigger companies and don't talk
>> about PostgreSQL as much. Often for fear of reprisals from other database
>> vendors they have ongoing relationships with.  At least that's been my
>> experience and I'm sure EDB folks will concur.
>
> In my experience PG isn't used much in production on Windows in bigger
> companies.

Well, there is indeed not much, but it is used. At least I work for
one and Postgres is embedded in a couple of products on Windows.

> It's used a *lot* (and is quite probably the most
> frequently downloaded build from EDB or postgresql.org) as an embedded
> database in some applications, and for development/test. There are a
> huge number of Windows PostgreSQL users out there.

And they don't those ones.
-- 
Michael


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Re: [HACKERS] Remove Windows crash dump support?

[Dave Page]

On Thu, Dec 24, 2015 at 2:14 AM, Craig Ringer  wrote:
> On 22 December 2015 at 23:48, Alex Ignatov  wrote:
>
>>
>> I think that you can debug crash dump since windbg exists.
>
>
> Nobody in their right mind uses windbg though. Visual Studio is really where
> it's at and the Express versions make it much more practical.
>
> You can't even install Debugging Tools for Windows and Windbg standalone
> anymore.
>
>>
>> Also I think that Postgres on Windows number  of instalations is so tiny
>> because people even today think that it is not so solid as unix version
>> thats why you think that nobody use your code ;).
>
>
> I disagree. Windows Pg users are often at bigger companies and don't talk
> about PostgreSQL as much. Often for fear of reprisals from other database
> vendors they have ongoing relationships with.  At least that's been my
> experience and I'm sure EDB folks will concur.

In my experience PG isn't used much in production on Windows in bigger
companies. It's used a *lot* (and is quite probably the most
frequently downloaded build from EDB or postgresql.org) as an embedded
database in some applications, and for development/test. There are a
huge number of Windows PostgreSQL users out there.

-- 
Dave Page
Blog: http://pgsnake.blogspot.com
Twitter: @pgsnake

EnterpriseDB UK: http://www.enterprisedb.com
The Enterprise PostgreSQL Company


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Re: [HACKERS] Remove Windows crash dump support?

[Craig Ringer]

On 22 December 2015 at 23:48, Alex Ignatov  wrote:


> I think that you can debug crash dump since windbg exists.
>

Nobody in their right mind uses windbg though. Visual Studio is really
where it's at and the Express versions make it much more practical.

You can't even install Debugging Tools for Windows and Windbg standalone
anymore.


> Also I think that Postgres on Windows number  of instalations is so tiny
> because people even today think that it is not so solid as unix version
> thats why you think that nobody use your code ;).
>

I disagree. Windows Pg users are often at bigger companies and don't talk
about PostgreSQL as much. Often for fear of reprisals from other database
vendors they have ongoing relationships with.  At least that's been my
experience and I'm sure EDB folks will concur.


> Today if my memory serves me right this code can not deal with buffer
> overflow. Am i right?
>

Stack overflow?

No, it can't. The stack has to be somewhat sane.


> May be we need to add this functionality instead of drop support of it
> entirely
>

Why? I've never seen any sign anybody has used it, ever.

-- 
 Craig Ringer   http://www.2ndQuadrant.com/
 PostgreSQL Development, 24x7 Support, Training & Services

Re: [HACKERS] Remove Windows crash dump support?

[Joshua D. Drake]

On 12/23/2015 06:14 PM, Craig Ringer wrote:

On 22 December 2015 at 23:48, Alex Ignatov > wrote:

I think that you can debug crash dump since windbg exists.


Nobody in their right mind uses windbg though. Visual Studio is really
where it's at and the Express versions make it much more practical.

You can't even install Debugging Tools for Windows and Windbg standalone
anymore.

Also I think that Postgres on Windows number  of instalations is so
tiny  because people even today think that it is not so solid as
unix version thats why you think that nobody use your code ;).


I disagree. Windows Pg users are often at bigger companies and don't
talk about PostgreSQL as much. Often for fear of reprisals from other
database vendors they have ongoing relationships with.  At least that's
been my experience and I'm sure EDB folks will concur.


I can speak from experience as well that Windows is unfortunately one of 
our larger installations. The fact is, many people run PostgreSQL on 
Windows and many never speak of it.


JD

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Re: [HACKERS] Remove Windows crash dump support?

[Craig Ringer]

On 22 December 2015 at 23:46, Tom Lane  wrote:

> > In which version(s) of Windows was this improvement added?


Vista and Server 2008 (original, not R2).

https://msdn.microsoft.com/en-us/library/windows/desktop/bb787181(v=vs.85).aspx

Win7 and Server 2003 are already irrelevant now, and will be absurdly so by
the time Pg 9.6 comes out.

The windows feature works better than the in-application crash dump. It can
limit the number of dumps, for one thing, and it doesn't require a sane and
intact stack to work.


> Even if it's all good in recent Windows, the impression I have is that an
> awful lot of people are still running older versions, so I'd be pretty
> hesitant to just drop the code.


Yeah, if it was new in Win2012 I'd agree, but it's been around since 2008.


> Also, AFAICS it's pretty self-contained
> and hence not much of a drag on development.  Is there any positive reason
> to remove it?


Not really. It also does nothing by default, so it's pretty harmless and
mostly dead code.

I just thought it was worth bringing up that there's a better way to do it
now and nobody seems to use it anyway.

-- 
 Craig Ringer   http://www.2ndQuadrant.com/
 PostgreSQL Development, 24x7 Support, Training & Services

[HACKERS] Remove Windows crash dump support?

[Craig Ringer]

Hi all

Back in 2010 I submitted a small feature to allow the creation of minidumps
when backends crashed; see commit dcb09b595f88a3bca6097a6acc17bf2ec935d55f .

At the time Windows lacked useful support for postmortem debugging and
crash-dump management in the operating system its self, especially for
applications running as services. That has since improved considerably.

The feature was also included in 9.4, which I think was the PostgreSQL
release that was really rock solid on Windows. Consequently it's never
served the purpose I wrote it for, a way to make it easy to get crash data
from end users into the hands of a developer without needing to
remote-debug the users' system.

It's practically dead code and we might as well remove it unless there's
someone out there using it who's keeping quiet about it.

-- 
 Craig Ringer   http://www.2ndQuadrant.com/
 PostgreSQL Development, 24x7 Support, Training & Services

Re: [HACKERS] Remove Windows crash dump support?

[Magnus Hagander]

On Tue, Dec 22, 2015 at 3:53 PM, Craig Ringer  wrote:

> On 22 December 2015 at 22:50, Craig Ringer  wrote:
>
>> Hi all
>>
>> Back in 2010 I submitted a small feature to allow the creation of
>> minidumps when backends crashed; see
>> commit dcb09b595f88a3bca6097a6acc17bf2ec935d55f .
>>
>> At the time Windows lacked useful support for postmortem debugging and
>> crash-dump management in the operating system its self, especially for
>> applications running as services. That has since improved considerably.
>>
>> The feature was also included in 9.4
>>
>
> Ahem. 9.1. This is what I get for multi-tasking between writing this and
> packaging an extension for 9.4.
>
>
In which version(s) of Windows was this improvement added? I think that's
really the part that matters here, not necessarily which version of
PostgreSQL.


-- 
 Magnus Hagander
 Me: http://www.hagander.net/
 Work: http://www.redpill-linpro.com/

Re: [HACKERS] Remove Windows crash dump support?

[Tom Lane]

Magnus Hagander  writes:
> On Tue, Dec 22, 2015 at 3:53 PM, Craig Ringer  wrote:
>>> Back in 2010 I submitted a small feature to allow the creation of
>>> minidumps when backends crashed; see
>>> commit dcb09b595f88a3bca6097a6acc17bf2ec935d55f .
>>> At the time Windows lacked useful support for postmortem debugging and
>>> crash-dump management in the operating system its self, especially for
>>> applications running as services. That has since improved considerably.

> In which version(s) of Windows was this improvement added? I think that's
> really the part that matters here, not necessarily which version of
> PostgreSQL.

Even if it's all good in recent Windows, the impression I have is that an
awful lot of people are still running older versions, so I'd be pretty
hesitant to just drop the code.  Also, AFAICS it's pretty self-contained
and hence not much of a drag on development.  Is there any positive reason
to remove it?  If the native facilities on newer Windows are better,
maybe we should teach the crash handler to install itself only on older
versions?

regards, tom lane


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Re: [HACKERS] Remove Windows crash dump support?

[Alex Ignatov]

On 22.12.2015 18:28, Magnus Hagander wrote:



On Tue, Dec 22, 2015 at 3:53 PM, Craig Ringer > wrote:


On 22 December 2015 at 22:50, Craig Ringer > wrote:

Hi all

Back in 2010 I submitted a small feature to allow the creation
of minidumps when backends crashed; see
commit dcb09b595f88a3bca6097a6acc17bf2ec935d55f .

At the time Windows lacked useful support for postmortem
debugging and crash-dump management in the operating system
its self, especially for applications running as services.
That has since improved considerably.

The feature was also included in 9.4


Ahem. 9.1. This is what I get for multi-tasking between writing
this and packaging an extension for 9.4.


In which version(s) of Windows was this improvement added? I think 
that's really the part that matters here, not necessarily which 
version of PostgreSQL.



--
 Magnus Hagander
 Me: http://www.hagander.net/
 Work: http://www.redpill-linpro.com/

Hi all!
I think that you can debug crash dump since windbg exists.
Also I think that Postgres on Windows number  of instalations is so 
tiny  because people even today think that it is not so solid as unix 
version thats why you think that nobody use your code ;).


Today if my memory serves me right this code can not deal with buffer 
overflow. Am i right?
May be we need to add this functionality instead of drop support of it 
entirely?


--
Alex Ignatov
Postgres Professional: http://www.postgrespro.com
The Russian Postgres Company

Re: [HACKERS] Remove Windows crash dump support?

[Craig Ringer]

On 22 December 2015 at 22:50, Craig Ringer  wrote:

> Hi all
>
> Back in 2010 I submitted a small feature to allow the creation of
> minidumps when backends crashed; see
> commit dcb09b595f88a3bca6097a6acc17bf2ec935d55f .
>
> At the time Windows lacked useful support for postmortem debugging and
> crash-dump management in the operating system its self, especially for
> applications running as services. That has since improved considerably.
>
> The feature was also included in 9.4
>

Ahem. 9.1. This is what I get for multi-tasking between writing this and
packaging an extension for 9.4.

-- 
 Craig Ringer   http://www.2ndQuadrant.com/
 PostgreSQL Development, 24x7 Support, Training & Services