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Sunday, April 06, 2008 - Posts
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A couple of people have commented on the previous entry , citing, essentially, that Google needs to do this to be "the best". I understand the argument completely: Google wants to attract the top talent, or retain the top talent, or at least entice the top talent, not to mention give them every reason to be horribly productive, so all of that extravagance is a justifiable--and some might argue necessary--expense. Thing is, I don't buy into that argument for a second. Talent wants to be rewarded, granted, but think about this for a moment: what kind of hours are these employees buying into by working there? There's an implicit tradeoff here, one that says, "If you are insanely productive, then the cost of this office is justified", meaning the pressure is on. Having an off day? Better pull the all-nighter to make up for it. Got stuck on something you didn't anticipate? Better pull the all-weekender to compensate. You're not in the bush leagues any more, sonny--you're at Google, and we paid a lot of money to make this office your home away from home, so snap to it! I'm not suggesting that Goole is explicitly demanding this of their employees... but neither did Microsoft, back in the day. See, all of this--including the justification arguments--is eerily reminiscent of Microsoft in their heyday, with the best example being the original Windows NT team. The hours they pulled over the last few months (some say years) of that project were nothing short of marathon sprints, and Microsoft laid everything they could at the feet of these developers (though nothing like what Google has built in Zurich, mind you) to help them focus on shipping the project. The Wall Street Journal ran an article about the whole thing, and one quote from that article stuck with me: that the pressure to work the insanely long hours didn't come from upper management, but from the other developers on the team. "Are you signed up for this thing or not?" was a euphemism for "Why the hell are you leaving at 9PM? And you're not back until 8AM? What are you, some kind of slacker?" (I felt like screaming back, "Just say no!", and I wasn't even there.) The peer pressure was insane, and drove several members of the team to get outta Dodge as the first opportunity. Or some took off for bike rides across the country to recharge. Or some just... broke. Microsoft doesn't do this anymore. Nobody is expected to put in 60 hour work weeks as a matter of course; now, the average is around 45, which I believe Read More...
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Kohsuke Kawagachi has posted a blog entry describing how to watch the assembly code get generated by the JVM during execution, using a non-product (debug or fastdebug) build of Hotspot and the -XX:+PrintOptoAssembly flag, a trick he says he learned while at TheServerSide Java Symposium a few weeks ago in Vegas. He goes on to do some analysis of the generated assembly instructions, offering up some interesting insights into the JVM's inner workings. There's only one problem with this: the flag doesn't exist. Looking at the source for the most recent builds of the JVM (b24, plus whatever new changesets have been applied to the Mercurial repositories since then), and in particular at the "globals.hpp" file (jdk7/hotspot/src/share/vm/runtime/globals.hpp), where all the -XX flags are described, no such flag exists. It obviously must have at one point, since he's obviously been able to use it to get an assembly dump (as must whomever taught him how to do it), but it's not there anymore. OK, OK, I lied. It never was there for the client build (near as I can tell), but it is there if you squint hard enough (jdk7/hotspot/src/share/vm/opto/c2_globals.hpp), but as the pathname to the source file implies, it's only there for the server build, which is why Kohsuke has to specify the "-server" flag on the command line; if you leave that off, you get an error message from the JVM saying the flag is unrecognized, leading you to believe Kohsuke (and whomever taught him this trick) is clearly a few megs shy in their mental heap. So when you try this trick, make sure to use "-server", and make sure to run methods enough to force JIT to take place (or set the JIT threshold using -XX:CompileThreshold=1) in order to see the assembly actually get generated. Oh, and make sure to swing the dead chicken--fresh, not frozen--by the neck over your head three times, counterclockwise, while facing the moon and chanting, "Ohwah... Tanidd... Eyah... Tiam...". If you don't, the whole thing won't work. Seriously. ... Ever feel like that's how we tune the JVM? Me too. The whole thing is this huge black box, and it's nearly impossible to extract any kind of useful information without wandering into the scores of mysterious "-XX" flags, each of which is barely documented, not guaranteed to do anything visibly useful, and barely understood by anybody outside of Sun. Hey, at least we have those flags in the JVM; the CLR developers have to take whatever the Microsoft guys give them. ("And they'll Read More...
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