"System call semantics?" [LWN.net]

"System call semantics?"

Posted May 17, 2006 17:58 UTC (Wed) by corbet (editor, #1)
In reply to: "System call semantics?" by cventers
Parent article: Java becomes more distributable

As noted in the article, it's an unlikely scenario. But if, say, Sun were to decide to pick on the relative thread-safety of the write() system call, there could be an issue here. When looking at licenses and contracts, it is good to keep an eye on what the language allows.

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"System call semantics?"

Posted May 17, 2006 19:05 UTC (Wed) by cventers (subscriber, #31465) [Link]

Well, I guess my curiosity is basically this - what would be the value of
Sun "picking on" a Linux vendor because of supposed incompatibilities? At
least how I see today's distributions operating, I think most of them
would (politically) tell Sun off. There are legions of Linux users like
myself that don't particularly care for Java. (Besides, as we all know,
there are some reasonably good open implementations that are hard at
work. The fact that we've had to do that tells me that Java is not a
language I'd ever choose [on a political or ideological level]...)

So perhaps the worry is that we'll all start shipping Sun Java, drop our
open implementations, become dependant and then Sun will have us by the
balls? (Of course, as you say, it's an unlikely scenario... but who knows
what a dying company might do if their entire operating system division
went South, leaving them with nothing but an enterprise language powering
far too much of the Internet...)

"System call semantics?"

Posted May 18, 2006 7:24 UTC (Thu) by pimlott (guest, #1535) [Link]

what would be the value of Sun "picking on" a Linux vendor because of supposed incompatibilities?

I suspect a more realistic scenario is: Java's threading is implemented using POSIX pthreads, but Linux threads aren't quite POSIX. This was in fact the case until recently, the cause of much griping by thread programmers (pour souls) and contention among Linux hackers. I believe this issue is now quite resolved, but if it weren't, I can imagine Sun refusing to allow distributors who ship the non-standard Linux threads to also ship Sun's Java. It's not too much of a stretch that this would tip the distributor's decision to switch to a new thread library. This could indeed break some other program relying on the old thread behavior.

"System call semantics?"

Posted May 18, 2006 16:49 UTC (Thu) by jonabbey (subscriber, #2736) [Link]

Actually, Java's threading semantics have always been relatively underspecified, specifically to make it possible to have Jave implementations on a wide variety of underlying operating systems.

Remember Java on Macintosh OS 9? ;-)

"System call semantics?"

Posted May 18, 2006 16:58 UTC (Thu) by pimlott (guest, #1535) [Link]

Remember Java on Macintosh OS 9? ;-)

checkmate, you win