PIA Load Balancing JVMs and Garbage Collection David

PIA Load Balancing, JVMs and Garbage Collection David Kurtz Go-Faster Consultancy Ltd. david. kurtz@go-faster. co. uk www. go-faster. co. uk

Who am I? • DBA • Book – Independent consultant • System Performance tuning – www. psftdba. com – People. Soft ERP – Oracle RDBMS • Training Course • UK Oracle User Group – Unix SIG • Oak Table – www. oaktable. net PSFT Tech PUG 5. 9. 05 www. go-faster. co. uk 2

Resources • If you can’t hear me say so now. • Please feel free to ask questions as we go along. • The presentation will be available from – www. go-faster. co. uk PSFT Tech PUG 5. 9. 05 www. go-faster. co. uk 3

A War Story • Two forms of load balancing 50. 0. 0. 50: 443 • PSFT Recommendations: Windows Network Load Balancing – IIS Proxy WEB 1 – Red Paper HA & Clustering PSFT Tech PUG 5. 9. 05 www. go-faster. co. uk IIS 50. 0. 0. 7: 443 PIA 1 50. 0. 0. 7: 7001 PIA 2 50. 0. 0. 7: 17001 WEB 2 IIS 50. 0. 0. 8: 443 PIA 1 50. 0. 0. 8: 7001 PIA 2 50. 0. 0. 8: 17001 4

Problems • Strange Pauses – Mostly to do with garbage collection • IIS Proxy wouldn’t load balance – All of load on one PIA or the other • Pauses cause IIS Proxy failover • On Failover users loose their sessions PSFT Tech PUG 5. 9. 05 www. go-faster. co. uk 5

IIS Load Balancing • iisproxy. ini Web. Logic. Cluster=50. 0. 0. 8: 7001, 50. 0. 0. 8: 17001 Dynamic. Server. List=OFF … PSFT Tech PUG 5. 9. 05 www. go-faster. co. uk 6

IIS Load Balancing • Uneven loading of PIAs caused overload of one PIA. • Duration of garbage collection with 100% of load on single PIA much higher PSFT Tech PUG 5. 9. 05 www. go-faster. co. uk 7

How do I know the load is balanced? • Web server access log • People. Soft Performance Monitor • PT>=8. 44 – Event 150: JVM Status – Event 152: Web Site Status – Event 153: Web Servlet Status PSFT Tech PUG 5. 9. 05 www. go-faster. co. uk 8

How do I know the load is balanced? PSFT Tech PUG 5. 9. 05 www. go-faster. co. uk 9

JVM Garbage Collection • Java Command Line Options – verbosegc • Writes to weblogic. log – Xloggc: <filename> 0. 000: [GC 46591 K->3553 K(518464 K), 0. 1262603 secs] 19. 604: [GC 50145 K->6662 K(518464 K), 0. 3389070 secs] 70. 052: [Full_GC 46565 K->10901 K(518464 K), 0. 9507536 secs] 90. 967: [Full_GC 55273 K->16571 K(518464 K), 1. 1008306 secs] PSFT Tech PUG 5. 9. 05 www. go-faster. co. uk 10

Garbage Collector Log 90. 967: [Full_GC 55273 K->16571 K(518464 K), 1. 1008306 secs] – Elapsed time since JVM started – Collection type – Size of live objects before and after GC – Total space available, less permanent objects – Duration of collection PSFT Tech PUG 5. 9. 05 www. go-faster. co. uk 11

Timestamps on GC log -XX: +Print. GCTime. Stamps • But I couldn’t get it to work! PSFT Tech PUG 5. 9. 05 www. go-faster. co. uk 12

Other Garbage Collection Options • -XX: +Use. Conc. Mark. Sweep. GC • -XX: +Use. Par. New. GC • -XX: +CMSParallel. Remark. Enabled • • Caveat: These options are not presented as being any kind of panacea, but something to consider. You need to do your own testing. BTW: I got the idea for this from a UKOUG Oracle Application Server SIG! PSFT Tech PUG 5. 9. 05 www. go-faster. co. uk 13

-XX: +Use. Conc. Mark. Sweep. GC • Concurrent Low Pause Collector • GC is, as far as possible, concurrent with the execution of the application. – Uses a separate thread • App is paused for shorter periods during GC • Only effective on multi-processor machines PSFT Tech PUG 5. 9. 05 www. go-faster. co. uk 14

-XX: +Use. Par. New. GC • Parallel young generation GC with concurrent GC – for multiprocessor machines, – enables multi threaded young generation collection – Application is not paused PSFT Tech PUG 5. 9. 05 www. go-faster. co. uk 15

-XX: +CMSParallel. Remark. Enabled • Reduces remark pauses PSFT Tech PUG 5. 9. 05 www. go-faster. co. uk 16

Default Garbage Collector • Individual GC duration PSFT Tech PUG 5. 9. 05 www. go-faster. co. uk 17

Parallel Garbage Collector • Individual GC duration PSFT Tech PUG 5. 9. 05 www. go-faster. co. uk 18

Default Garbage Collector • Cumulative GC duration / minute PSFT Tech PUG 5. 9. 05 www. go-faster. co. uk 19

Parallel Garbage Collection • Cumulative GC duration / minute PSFT Tech PUG 5. 9. 05 www. go-faster. co. uk 20

Conclusion • Improved GC performance does not have a great effect on Component Performance • It does reduce the ‘strange pause’ giving the user a better experience • Parallel GC seems to slowly leak memory. – Possible bug in a particular JVM – I have only tested on Windows PSFT Tech PUG 5. 9. 05 www. go-faster. co. uk 21

Questions? PSFT Tech PUG 5. 9. 05 www. go-faster. co. uk 22

PIA Load Balancing, JVMs and Garbage Collection David Kurtz Go-Faster Consultancy Ltd. david. kurtz@go-faster. co. uk www. go-faster. co. uk