JavaOne summary

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JavaOne 2010 Summary.

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JavaOne summary

  1. 1. <Insert Picture Here> JavaOne Summary bluedavy http://blog.bluedavy.com 2010-10-4
  2. 2. Agenda • Trends • Overview • Details • Summary 2
  3. 3. Trends • Fire IBM、Salesforce.com – Software,Hardware,Complete. 3
  4. 4. Trends • JavaSE – JDK 7 used plan b,plan release at 2011 mid,Java 8 plan release at 2012 late. – Improved Networking based on Native Infiniband; – Optimize Java for new app models & new hardware; – Multilanguage supports. • JavaEE – Nothing important • Java Client – 2D & 3D – HTML 5 – More Actions... 4
  5. 5. Overview • I attended 24 sessions of 370,two types: JVM, experience talk. • I learned a lot,but google’s absence is a large pity. 5
  6. 6. Details • JVM – GC – Memory Leak – Native Memory – Hot code replace – Multicore – Monitor and Profiler • Experience Talk 6
  7. 7. Details • JVM – GC • Tony said:”this is my favorite session”; – Cliff click said in another session:”if JVM vendor can provider one flag to control memory,then gc don’t need talk about again”. • GC Tuning,ParallelOldGC first,if pause time too long,then CMS; • CMS GC Tuning tips: such as set CMSInitiatingOccupancyFraction properly; turn on ParallelRefProcEnabled etc; • set Tenuring Threshold properly; • Finalizers should be avoided; • GC Myth,such as gc explicit deallocation would improve performance,gc eliminates all memory leaks,I can a high throughput and low pause gc. • System.identityHashCode() causes gc slow 7
  8. 8. Details • JVM – Memory Leak • PermGen memory leak,tomcat add a MemoryLeakProtection; • Use MAT to analyze memory leak; • a simple and classic example by Tony; File f=new File(fileName); Image img=readImage(f); imageMap.put(f,img); f=null; 8
  9. 9. Details • JVM – Native Memory • ppt is very good and total,from os memory model,jvm memory model to how jvm use native memory; • recommend os tools such as pmap to find who use native memory; – I think it’s not good,seems google perftools is the best solution now. 9
  10. 10. Details • JVM – Hot code replace • u can use hotswap or discarding classloaders,but they’re not good; • current product: fastswap in weblogic;JRebel;FaceReplace;Spring Loaded; • Spring Loaded seems very good from demo; – method reloading: basically loosen caller/callee coupling; – field reloading: intercept field accesses. 10
  11. 11. Details • JVM – Multicore • Lambda; • Fork/Join in JDK7; • AKKA; • Actors; • GPU based; 11
  12. 12. Details • JVM – Monitor and Profiler • VisualVM; – Tracker plugin seems good; • JRockit Mission Control(JRMC); – Very cool,rockstar,appearance rate is very high; – Maybe after two years,we can use it on hotspot,; • Palantir – Just another commerical tool,based on DTrace; • HProf – why not use it? 12
  13. 13. Details • Experience Talk – How to Tune and Write Low-Latency Applications on the Java Virtual Machine • Understand your data structures,such as size your hashmap correctly; • GC friendly data structures; • Use Reference Objects Sensibly; • Profiling,such as gc analysis; • Analyze your app,include gc,hot methods,lock contention,IO events; 13
  14. 14. Details • Experience Talk – Too Big to Fail: Top Tips for Massive, Mission-Critical Enterprise Applications • CompressedOOPS • NUMA • HProf • Share read-only data use NewDirectByteBuffer • NanoTime • beaware identity hashcode 14
  15. 15. Details • Experience Talk – Top 10 Causes for Java Issues in Production and What to Do When Things Go Wrong • Instrumentation is not cheap; – I don’t know how cliff click think about jrockit flight recorder; • leaks; • I/O; • Locks & synchronized; • Endless compilation,exceptions; • Fragmentation; • GC Tuning; • Spikes; • Versionitis; 15
  16. 16. Summary • The session content and speaker are two important factors for choose session; • Many speakers are from india,seems india engineer are go into tech core; • The level of attendees are unevenness; • Exchange with speakers are important,so u should prepare what do u want to know more?; 16
  17. 17. Bonus - photos 17

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