Date: Sun, 23 Feb 2003 08:59:58 -0800 (PST) From: Nick Johnson <freebsd@spatula.net> To: freebsd-java@freebsd.org Subject: jdk1.3.1-p8 with hotspot notes Message-ID: <20030223084255.R74143@turing.morons.org>
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First, I'm really stoked about this, because FreeBSD has been missing out on a huge server market by not having a viable, high-performance Java platform. This is going to be huge for FreeBSD. Second, a couple random notes about hotspot with jdk1.3.1-p8: o "compiler1" is also known as the client VM. "compiler2" is the server VM. As you might imagine, compiler1 is tuned for interactive apps like GUIs and things, and complier2 is more tuned for servlet engines and the like. o compiler2 has a load characteristic you might find disconcerting, but by all counts it's normal. When you start up your app, it's quite aggressive about compiling stuff it seems, so the load spikes upon startup, stays high for a while, and then tapers off. Mine was using 20-30% CPU for the first 10 minutes of my app running, and now rarely exceeds 5% o using -Xincgc sounds like a good idea but it isn't. The idea is to fix a problem Java's had for some time where garbage collection tended to be done in big hunks, causing short periods of severe performance degradation. Incremental GC was supposed to smooth that out, but what it turns out to do is just make performance bad -all- the time. Googling around a bit, I've found this is a complaint on many platforms; it's not an issue with the FreeBSD implementation. Probably this is why it isn't on by default. o Using native threads may expose bugs in your Java code that weren't there with green threads. In particular, if you were relying on attributes being set in a bean in a particular order, you are in for trouble. I was doing something foolish in this regard, and it came back to bite me. Lesson learned! o morons.org is now running with jdk1.3.1-p8 with the server VM and has been for about 18 hours now. So far, no ill effects, and the servlet container even withstood an attack already. Memory consumption is approximately what it was before, but perhaps a tiny amount less. Load is definitely less than 1.3.1-p7 with OpenJIT. Response time is a bit better (though some of it is lost by virtue of the way the web works). Hasn't crashed yet! Nick -- "The aptly-named morons.org is an obscenity-laced screed..." -- Robert P. Lockwood, Catholic League director of research Nick Johnson, version 2.0 http://www.spatula.net/ To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-java" in the body of the message
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