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An Unbelievable Demo

brendangregg.com

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Re: An Unbelievable Demo

#161

Post by BBC-vs-neolibs »

sgtnoodle wrote: post #140
oblio wrote: post #116

Earlier quoted context omitted.

> One of the reasons games do this is the data is compressed, so a "patch" might be indistinguishable from a real update. Does this happen with more advanced compression algorithms? I've rsynced zip files of different versions of internal software and the diff was always much, much smaller than the entire package.

Zip files have all the metadata in a footer rather than a header. As a result, compressed files can be added and overwritten by appending to the file without disturbing already compressed data. Additionally, the "deflate" compression likely does not span across files, so files that did not change from version to version would have a similar compressed byte sequence, regardless of the order they were added to the arch…

zstd strikes a nice balance here. It can inject markers in the bytestream to make it "rsync friendly", but one could just as well say "binary diff friendly".

zstd itself also has the (pretty new) ability to use a shared file as shorthand during compression. What that means in practice is that diffs can be REALLY tiny if you have the previous archive download.

Hi dang.

Re: An Unbelievable Demo

#162

Post by Aachen »

Twirrim wrote: post #89

Years ago, I interviewed a candidate for a role on my team. As usual, one of the ways I break the ice with candidates is to get them to talk "war stories". The team he'd worked on had produced a tool that was only ever intended to be used by the team to solve a particular problem they had. It contained proprietary code. Unknown to the team, word had spread about the tool, and others had started to use it, including s…

> having to rapidly re-architect the tool around a non-GPLv3 licensed library

... or just go with it and have it be open source? The old version is already open and free for anyone to request the code of. No rush at that point, you can withhold updates for a little while while you rearchitect this or take the situation as it is and have the next few bugfix releases also fall under GPL until you get around to replacing the core component (iff one insists that the future additions must absolutely be proprietary).

Quickly removing the code doesn't change the previously released versions' license.

Re: An Unbelievable Demo

#163

Post by wruza »

maccard wrote: post #125
oblio wrote: post #116

Earlier quoted context omitted.

> One of the reasons games do this is the data is compressed, so a "patch" might be indistinguishable from a real update. Does this happen with more advanced compression algorithms? I've rsynced zip files of different versions of internal software and the diff was always much, much smaller than the entire package.

I can't say, I'm not sure what compression we used on the last two games I worked on, sorry!

It is very unlikely that it was a “continuous” compression anyway. Continuous archives disallow random file access property, and games require exactly that for assets. You can’t decompress few gb on average to fetch a sprite of a cat.

The reason games (and software in general) do full downloads instead of binary patches is purely overdefensive and/or stupid. Store software could just check checksums after a patch and re-download only if they fail.

Re: An Unbelievable Demo

#164

Post by rorykoehler »

brendangregg wrote: post #33
BrissyCoder wrote: post #10

Were there any legal repercussions? Was the employee fired? Were you as calm about this at the time as you seem now?... I would be furious! EDIT: For some reason I assumed OP was the author. Someone with a twitter account should ping him and get him over here to participate in discussion.

I was in shock, and a bit furious at being ripped off, but didn't feel there was a lot I could do about it. I edited this bit out (I was trimming the post): "You might wonder why I didn't talk about this first case publicly at the time. I'd already informed them of the problem privately and how to fix it, so there wasn't more to say. Also, Sun was the number one employer in town, and to be publicly critical could be…

Are there no legal recourse options for breaking the license so blatantly?

Re: An Unbelievable Demo

#165

Post by dijit »

sam_lowry_ wrote: post #95
thundergolfer wrote: post #16

Thankfully the "DTrace expert" didn't turn out to be Bryan Cantrill. He's a big fan of Scott McNealy's engineering principles for Sun Microsystems, which includes "Don't Cheat", and the behaviour in this story very much seems not in the spirit of that principle. I wonder if this bit of 'cheating' ended up getting someone at Sun in trouble.

You do not know.

Given that Brenden and Bryan worked together closely and seemed to be very fond of each other; and the article mentions that "the VIP may not have known" I think it's safe to assume it was not Bryan.

As if it had been Bryan, Brenden would have been more sure.

Re: An Unbelievable Demo

#167

Post by versteegen »

sgtnoodle wrote: post #140
oblio wrote: post #116

Earlier quoted context omitted.

> One of the reasons games do this is the data is compressed, so a "patch" might be indistinguishable from a real update. Does this happen with more advanced compression algorithms? I've rsynced zip files of different versions of internal software and the diff was always much, much smaller than the entire package.

Zip files have all the metadata in a footer rather than a header. As a result, compressed files can be added and overwritten by appending to the file without disturbing already compressed data. Additionally, the "deflate" compression likely does not span across files, so files that did not change from version to version would have a similar compressed byte sequence, regardless of the order they were added to the arch…

> Additionally, the "deflate" compression likely does not span across files

Clarification: .zip (unlike .tar.gz for example, or "solid" .7z) compresses each file separately, that's nothing to do with the compression algorithm used. In addition, DEFLATE, the LZ77-based compression which is by far most commonly used in .zip (and also by gzip) has a window size of 32kB (uncompressed). So yes, even if you used DEFLATE on a solid stream (e.g. zipped a .tar archive) it couldn't remove any cross-file redundancy once it's gone past the first 32kB of each file.

Re: An Unbelievable Demo

#168

Post by DonHopkins »

>The belief at Sun that only Sun could make good use of its own technologies, and anything created outside of Sun was trash.

As a former Sun employee, I can tell you that's true: people at Sun wouldn't even look at competing technologies because they were sure there was nothing useful to be learned from them.

That's why Bill Gates and Anders Hejlsberg were able to screw Sun so badly by examining and copying the good things about Java, and making something much better: C# and CLR.

While Sun totally failed to learn from any of the good things that Microsoft or Apple or anyone else did.

>We are better off with all the wood behind one arrow.

Nice reference to the old Sun slogan and 1999 April Fools Day prank, in which Sun employees put an enormous arrow through Scott McNealy's office.

https://findery.com/johnfox/notes/all-the-wood-behind-one-ar...

All your wood notwithstanding, it also helps to chose an arrow that isn't flawed and doesn't totally miss the target. For what it's worth, Scott McNealy also put all his wood behind another arrow named Donald Trump.

Scott McNealy has long been one of Trump's few friends in Silicon Valley

https://www.sfchronicle.com/politics/article/Scott-McNealy-h...

Trump held fundraiser at former Sun CEO Scott McNealy’s Silicon Valley house on Tuesday

https://www.cnbc.com/2019/09/17/trump-silicon-valley-fundrai...

Scott McNealy gets touchy feely with Trump: Sun cofounder hosts hush-hush reelection fundraiser for President

https://www.theregister.com/2019/09/17/mcnealy_trump_fundrai...

Re: An Unbelievable Demo

#169

Post by apendleton »

sam_lowry_ wrote: post #95
thundergolfer wrote: post #16

Thankfully the "DTrace expert" didn't turn out to be Bryan Cantrill. He's a big fan of Scott McNealy's engineering principles for Sun Microsystems, which includes "Don't Cheat", and the behaviour in this story very much seems not in the spirit of that principle. I wonder if this bit of 'cheating' ended up getting someone at Sun in trouble.

You do not know.

To the extent that the two of them have disagreed about things, they don't seem to have any issue saying so publicly, referring to the other by name: https://news.ycombinator.com/item?id=16382456

Re: An Unbelievable Demo

#170

Post by Intermernet »

oblio wrote: post #154
ZephyrBlu wrote: post #41

Earlier quoted context omitted.

I think there are lower expectations of Aus/NZ because they're relatively small and out-of-the-way countries (Maybe less so for Aussie), so it's surprising how often they seem to excel in things. The obvious examples that come to mind would be sports. NZ excels in Sailing, Cricket and Rugby against much larger countries. Though it could be that in general, Aus/NZ have the same skill distribution as other countries, b…

> The obvious examples that come to mind would be sports. NZ excels in Sailing, Cricket and Rugby against much larger countries. Those are niche sports, very popular in that part of the world. They're not major sports, though. Cricket is sort of a major sport, but it's also very culturally concentrated. Outside of UK & some former UK colonies, almost nobody plays it/watches it. Does New Zealand have any famous footba…

Edmund Hillary?
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