<div>I've attached an old gclog where it has similar behavior on the heap. But the problem with that is it takes quite a long time, like 20 - 70 seconds. The server basically went down with customers complaining during that time, so we had to try CMS, but that doesn't work out well either.</div>
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<div>We are having Sun Portal Server 6.2 on those web servers. Do you know is it a normal behavior for Portal Server with about 400-500 users per instance?</div>
<div>Thanks,</div>
<div>TK<br><br></div>
<div class="gmail_quote">On Thu, Mar 27, 2008 at 5:10 PM, Jon Masamitsu <<a href="mailto:Jon.Masamitsu@sun.com">Jon.Masamitsu@sun.com</a>> wrote:<br>
<blockquote class="gmail_quote" style="PADDING-LEFT: 1ex; MARGIN: 0px 0px 0px 0.8ex; BORDER-LEFT: #ccc 1px solid">Late in this log I see<br><br>162417.510: [GC 162417.510: [ParNew: 370176K->11520K(381696K), 0.4232456<br>
secs] 3055096K->2715938K(3134208K), 0.4240171 secs]<br><br>At that point the heap is about 85% full (2715938K/3134208K). The<br>tenured generation is almost completely full.<br><br>Do you have similar logs when using the default GC? We could use them<br>
to verify the amount of live data.<br>
<div class="Ih2E3d"><br><br>T.K wrote:<br>><br>> Hi Jon,<br>><br>> Here's the attached gclog. It starts out fine when we put in the change<br>> in the evening. Eventually, the next morning (around 60000 seconds on<br>
> gc time) when the load starting to get in, CMS starts to run<br>> consectively. The first CMS fails occur when we bump up the users to<br>> 700+, and almost kill the server. Ever since then, I don't see the CMS<br>
> ever stops, even when the load goes down to 50 users.<br>><br>> I cut off the logs in between into 3 portion so that I can attach it. :D<br>><br>><br>> Thanks,<br>> TK<br>><br>><br>> On 3/27/08, *Jon Masamitsu* <<a href="mailto:Jon.Masamitsu@sun.com">Jon.Masamitsu@sun.com</a><br>
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<div class="Wj3C7c">> <mailto:<a href="mailto:Jon.Masamitsu@sun.com">Jon.Masamitsu@sun.com</a>>> wrote:<br>><br>> Using CMS sometimes needs some tuning (especially<br>> with the 1.4.2 jdk). Do you have any gc logs<br>
> (-XX:+PrintGCDetails) so we can see what's happening?<br>><br>><br>> T.K wrote:<br>> > Hi All,<br>> > We got 5 Sun Web Servers running on Java 1.4.2, and used to use the<br>
> > default GC for Tenured space. The problem with that is that it takes<br>> > 60-80 seconds everytime the GC happens, and the latency on the<br>> site goes<br>> > crazy. So we decided to change it to use the Concurrent Mark Sweep<br>
> > Collector on one server to test it out. Here's the setting:<br>> ><br>> > -XX:+UseConcMarkSweepGC -XX:+UseParNewGC -Xms3G -Xmx3G<br>> -XX:NewSize=384M<br>> > -XX:MaxNewSize=384M -XX:PermSize=64M -XX:MaxPermSize=64M<br>
> > -XX:CMSInitiatingOccupancyFraction=60<br>> ><br>> > With that setting, the server runs great. But eventually, when the<br>> > server reach a medium load (around 100-200 users), the tenured<br>
> space is<br>> > always around half full, and the CMS collector starts to run<br>> > continuously one after another. It doesn't hurt the application<br>> for now,<br>> > but it's taking 25% of processing time (we got 4 cpu, so one web<br>
> server<br>> > always keep 1 cpu power). I don't see that much cpu utilization<br>> on other<br>> > web server that don't have CMS, and they have more users than the one<br>> > with CMS. If we got CMS on all 5 web servers, I'm wondering if<br>
> that will<br>> > crash the server or not. What should I do to decrease the processor<br>> > utilization caused by GC?<br>> ><br>> > Also, I'm thinking to use i-CMS on the JVM, and maybe that might slow<br>
> > down the CMS and reduce the amount of CPU utilization by CMS. Any<br>> thought?<br>> ><br>> > Thanks,<br>> > TK<br>> ><br>> ><br>> ><br>
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