PostgreSQL automatic crash dumps for windows

It seems my first real* PostgreSQL patch has been accepted and committed! By the time patch review was done I think it was almost more Magnus Hagander's patch than mine, but I'm still very happy to have put it together and seen it through into Pg mainline. Thanks very much to Marcus for testing, enhancing and committing the patch.

PostgreSQL 9.1 will now have automatic crash dump generation under Windows. That'll allow Windows users to run their production sites with crash dumps so we can do post-mortem debugging without holding up their server or requiring them to run it under a debugger. That gives us a much better chance of tracking down the cause of hard-to reproduce or intermittent faults. To activate the crash dump collection feature, just create a crashdumps directory in the data directory and grant the postgres user (or whatever user your server runs under) "full control" of that folder in Properties->Security. No configuration file changes or server re-starts are needed.

Helpfully, this change will also let the majority who don't know what Visual Studio or windbg.exe are send crash dumps off to someone more experienced with the tools already configured. There should be much less need for this page - and while it took me long enough to write, I'll be glad to see it rendered unnecessary.

* The one-liner fix for the X.509 client certificate validation bug doesn't really count, despite the truly epic amount of convincing required to get the patch applied.

Kogan KGN1080P32VAA - Avoid this TV and any other with a CultraView CV119MA mainboard

The Kogan KGN1080P32VAA TV is a lemon. Avoid it, and Kogan.

Support

Before I go on, I want to note that Kogan's support were responsive, if not helpful, about these issues. They acknowledged the EDID defect, and while they won't fix it or anything else that's wrong with the TV they did credit me $40 for my trouble, showing some sign they accept their error. Kogan have been much better than, say, Belkin when it comes to supporting their products. Given that they still haven't actually fixed anything, that says scary things about the industry, doesn't it? Anyway, here's why you should avoid this product, anything else by CultraView, and possibly anything else by Kogan:

720p EDID on a 1080p panel, mainboard programmed wrong

When I bought the KGN1080P32VAA I expected (and got) a 1080p TV with cheap and nasty LCD panel; this is, after all, a $600 1080p TV. Fine, you get what you pay for, and it's still a 1080p full HD panel.

What I didn't expect was an incorrectly programmed mainboard that sends the EDID for a 720p TV rather than a 1080p TV, making the TV not "full hd" at all (and in fact worse than native 720p due to scaling) for anything that respects the EDID! What does this say about quality control and product testing? I certainly didn't expect Kogan to have no interest in issuing a firmware update to fix it, given that the TV's mainboard, by physical examination determined to be the CultraView CV119MA is still in production and supports firmware updates via USB key. CultraView don't respond to queries and don't offer their tools or firmware for download without a username and password to their vendor/partner FTP site. Kogan say:

We have tried to get a firmware upgrade for you TV however we cannot get solution for this issue.

I would still suggest you to use the VGA as you get Full HD resolution on VGA without any issue.

Alas, there's only one VGA input and associated 3.5mm audio port. I didn't buy a TV with only one (working) input. Additionally, at 1920x1080 the (analog) VGA looks ... kind of nasty. This is partly explained by the picture issue described later.

HDMI audio and overscan

The problems with HDMI don't end with the EDID, though. The CultraView CV119MA, as shipped by Kogan, turns on overscan on digital inputs when it detects a HDMI audio signal. No HDMI audio, no overscan. HDMI audio, overscan. This means you can't get decent picture quality and HDMI audio at the same time - you have to endure the image butchery of overscan and overscan compensation, or have no audio on that input. Overscan makes no sense for digital inputs, where a perfect 1:1 pixel representation is sent and there are no scan line fringes, etc, to deal with. Sadly overscan does need to be an option because some older/broken digital output devices produce images with overscan for compatibility with ancient TVs, but should never be the default, and is something you must be able to disable. It certainly shouldn't be controlled by whether or not HDMI audio is being sent!

It's possible to disable overscan by disabling HDMI audio - if your device supports this. For my media PC, that requires telling the nVidia driver to completely ignore the EDID so it doesn't detect the HDMI audio capability of the output. I had to override the EDID anyway because the TV sends a totally bogus EDID with only 1080i and 720p resolutions over HDMI. There are a couple of ways to override the EDID though - I found that overriding just the resolutions left me with an overscanned 1080p image, while overriding the whole EDID got me a 1:1 pixel sharp-ish 1080p image. The difference: HDMI audio.

The TV doesn't offer a "1:1 pixel" mode in its zoom/aspect list, nor in its menus. The only way to control overscan is via HDMI audio. I'm gobsmacked.

Vendors unwilling to fix anything

Neither Kogan nor CultraView will supply a firmware update, or the tools to create one using the vendor customisation tools CultraView offer to vendors. Neither will supply the documentation for the mainboard, which has "PC DEBUG" (JTAG?) and "PC INPUT" (DB9 serial headers? Maybe?) on it and has updatable firmware. Examination of a firmware image I found on the 'net confirms that it's capable of being reflashed via USB.

Brightness controls pixel values not backlight

The problems don't end with a misprogrammed EDID and idiotic overscanning behaviour there, though. When you change the "brightness" setting in the TV, it doesn't adjust the backlight, it scales the pixel values down toward the black end, so you lose contrast and get horrid banding. While this can be written off as a "cheap TV" problem, it's one I never even imagined might be possible.

Horizontal blur at native 1080p

Worse: Even now that I've finally achieved a non-overscanned image at the panel's native 1080p resolution, the image is still crap. By creating a few stippled and striped b&w test patterns, I was able to determine that horizontal lines are sharp and clear - so there's no vertical scaling or distortion. An array of 1-pixel wide b&w vertical lines, though, are blurred and smudged when displayed on the TV, as if they've been scaled down then up, or up then down, before display.

The test image, unscaled, appears below. If your LCD display is set to native resolution and your browser isn't scaling the image, this image should appear as a block of fine vertical lines.

... and here's a photo of what you see on the Kogan TV. The connected machine was running Linux, but I see the same problem under Windows 7's (to use Media Center) over HDMI:

Here's an image I scaled down by 5%, then back up to original size, which demonstrates a similar effect:

Imagine what this does to text, typefaces, and most kinds of pattern. Argh!

It's just too crap

Before you say "It's a TV, not a computer monitor", let me quote from Kogan's product page for their new model 32" 1080p HD TV, the 1080P-BD32:

32"/ 81cm Full HD panel (1920x1080)
Full High Definition panel ensuring crystal clear TV with Progressive Scan up to 1080P. Doubles up as an excellent computer monitor.

While that text did not appear on the product page for my TV, it shows that Kogan, like me, think that it's reasonable to use modern HDTVs as monitors. In any case, I'm using mine for a lounge room media PC, not a regular PC, and just want it to work! I don't expect amazing quality, but actually displaying the pixels I send it and doing so with working HDMI audio surely isn't too much to ask?

After hours of work and several conversations with Kogan, I finally have the TV running at its rated 1920x1080 (1080p) resolution without horribly butchering the image with overscan. Of course, to get that far I had to override the EDID and disable HDMI audio. If there's no HDMI audio signal the TV plays the 3.5mm input on all HDMI channels - but that means you have only one input for all your channels, making the HDMI combined audio/video feature spectacularly useless, and rendering the TV effectively capable of only one distinct A+V input among from the 2 HDMI and 1 VGA ports. Needless to say, this sucks.

At this point the TV is annoying me enough that I'm planning on gutting my old laptop and using its 1080p capable LVDS output to drive the TV's panel directly, bypassing the TV mainboard. That way I'll be able to see how much of this is the panel and how much is that CultraView mainboard. If the panel is OK, I'll grab a little ARM or Via Nano board with a couple of HDMI inputs and a high-res LVDS output and build that into the case as an embedded media PC, getting rid of the CultraView part entirely.

Well, I've certainly learned one thing. I won't be buying from Kogan again unless I can test the product in person with my equipment before buying. They assemble products from 3rd party parts - which I knew. They don't push issues back to those suppliers and get fixes for them, which I didn't know and didn't expect. Poor show, Kogan.

Are you a programmer+sysadmin+support person at a small company? You need to read this.

I'm a sysadmin, developer of in-house software, and end-user tech support person at a small company. I wear a lot of hats, and do everything from Java EE applications to data recovery from crashed user laptops. If you can't open that email attachment or get to that website, I'm your man.

Needless to say, this makes the programming side rather challenging. I've always thought of interruption as the enemy of effective programming, and I've observed my effectiveness falling as the rate of interruption increases.

This article gives me reason to reconsider that idea, and consider trying to plan for and work with interruption instead. I cannot recommend it enough.

http://www.stevestreeting.com/2010/09/04/work-2-0/

On SSDs

I suspect that some of the ideas behind the design of SSD drives as currently sold are rather flawed. Update: See the end of the article for an alternative viewpoint, though.

These drives are embedded computers, with their own CPUs, RAM, firmware, etc. They are much more complicated than they should be for a simple storage device, and are more like mini RAID controllers than they are like hard disks.

Notes on gdb use

I find myself looking up how to do certain things with gdb, because I use it rarely enough not to remember, but frequently enough for these to be somewhat annoying. This post notes how to handle things like signals and paging in gdb.

BoB (Belkin F1PI243EGau) DNS is still broken

Update Oct 19, 2010:Contacting Belkin sales and customer feedback and pointing out my increasing efforts to show how poorly they've performed in public finally got a response from Belkin. Admittedly the response is to say they've put the issue though to an "overseas engineer" ... but maybe something will happen. More likely, it'll stay trapped in another layer of disinterest and poor management, this time one I can't apply direct pressure to.

UPDATE Oct 6, 2010:An indirect approach, by bothering a friend who works at iiNet, got this issue through the support wall and to people who can deal with it. Belkin has been notified at a higher level too. It's a real shame that a clearly demonstrable issue like this got stuck behind support people at both companies, to the point where I had to bother a friend who shouldn't have to deal with this stuff just to get the issue looked into. Sometimes tech support acts as a barrier that prevents a company from finding out about real problems, an issue I've seen not only with iiNet and Belkin but with endless other companies. Anyway, hopefully Belkin will be getting onto this now.

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A year ago, I reported to iiNet that AAAA lookups in the BoB (F1PI243EGau) DNS forwarder were always timing out, rather than returning SERVFAIL or correctly forwarding the query to the upstream server. This is the cause of the slow browsing issues reported for the BoB.

A couple of months ago I got hold of a pre-release firmware that fixed this, and about a month ago the firmware was finally put up for public use. This fixes the AAAA issues, so browsers like Firefox and Safari on IPv6-capable operating systems like Mac OS X and Windows 7 don't take an eternity to resolve every DNS query.

Unfortunately, Belkin didn't take this as a hint to properly test their DNS forwarder. They fixed AAAA lookup, but didn't fix it to return SERVFAIL when it encountered something it didn't understand, and failed to test other record types like TXT and SRV.

Sure enough, TXT and SRV lookup have the same problem. This is currently causing problems with Google Talk (using Pidgin) that require the configuration of a fallback connect server to bypass TXT record lookup.

Belkin support do not understand the problem. The low-level support folks at iiNet don't seem to get it either. Neither are passing the problem on to somebody with the experience and knowledge to understand the problem, and neither seem to have access to suitable hardware - or the inclination to use it if they do - to verify the issue.

Here's the explanation I sent to them.

Exception breakpoints

Do you have a StackOverflowError thrown deep inside some (probably 3rd party) code like EclipseLink's Criteria API? Are you trying to track down exactly where it's being thrown and under what circumstances? Is it driving you insane?

Use an exception breakpoint. In Netbeans: Debug -> New Breakpoint. Breakpoint type "Exception". Specify the exception class being thrown, constrain the throwing class if desired, and you're set.

This made my life a lot, lot, LOT easier recently. Thanks again NetBeans.