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Mon Feb 11 11:47:44 HKT 2013
From /weblog/java/discussion
These look interesting, worth to take a look: 1) Auto null checking: http://www.jroller.com[..]ebourne?entry=adding_auto_null_checks_to I don't think this is a good idea as I don't think there is a way can handle default object reference more generic then NULL. However, I would like to have a way to customize NULL behaviour (or default NULL object). Say, for String, I will think empty string ("") is same as NULL. Thus, I would like to have define something like:
public final class Strinig {
null {
return "";
}
// the rest of string implementation
}
Then the default reference of String, rather than point to NULL, now it point to an empty String. 2) Add closure to Java: http://www.jroller.com[..]ebourne?entry=adding_closures_to_java_or Not much comment, it is something nice to have but I don't think really add a lot of value, just like java5 foreach loop. 3) Auto casting: http://jroller.com[..]lebourne?entry=adding_auto_casts_to_java I guess generic already does this? Of course, there are still some other problem on some people's mind, like: http://www.onlamp.com/lpt/a/3691 http://nice.sourceforge.net/safety.html On the other hand, somebody don't like to change java language as it probably make your code less portable. http://www.eclipsezone.com/eclipse/forums/t54318.html 4) Some idea of useful util language - http://closingbraces.net/2007/03/05/strangelets/ 5) API for adding feature - http://www.theserverside.com[..]s?track=NL-461&ad=636686&thread_id=49035 A lot more other idea - http://blog.jooq.org/2013/02/04/java-if-this-were-a-better-world/ Drop extends - http://www.javaworld.com[..]at-if-java-8-dropped-extends.html?page=2
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Tue Jan 01 18:07:14 HKT 2013
From /weblog/java/performance
Using generational & concurrent GC collector - http://www.javacodegeeks.com[..]/04/ibm-jvm-tuning-gencon-gc-policy.html Full VM option list : http://blogs.sun.com/roller/resources/watt/jvm-options-list.html, update for Java7 - http://nerds-central.blogspot.com[..]ot.com/2011/07/all-jvm-7-xx-options.html http://stas-blogspot.blogspot.com[..]ost-complete-list-of-xx-options-for.html HotSpot JVM garbage collection options cheat sheet - http://aragozin.blogspot.com[..]spot-jvm-garbage-collection-options.html http://www.oracle.com[..]va/javase/tech/vmoptions-jsp-140102.html An example and story about effect of difference VM parameter affecting the performance - http://www.javaspecialists.eu/archive/Issue191.html Clear the code cache automatically with -XX:+UseCodeCacheFlushing - http://blogs.amd.com[..]time-for-long-running-java-applications/ Discussion about -XX:MinHeapFreeRatio parameter - http://www.gossamer-threads.com[..]s.com/lists/lucene/java-user/44286#44286 The other detailed guide for VM parameters tuning - http://java.sun.com/j2se/1.5/pdf/jdk50_ts_guide.pdf Here is a more simple cookbook - http://java.sun.com/performance/reference/whitepapers/tuning.html A outdated (1.4) , compehensive but still not really too detailed, overview of various GC tuning - http://www.petefreitag.com/articles/gctuning/ Some say following VM parameter is good enough -server -Xmx -XX:+UseParallelGC http://blogs.sun.com[..]/page/binublog?entry=java_tuning_for_xml Some say is useful if you have huge memory -XX:+UseLargePages http://blogs.sun.com[..]dagastine?entry=java_se_tuning_tip_large Some say below parameter keep GC in low pause -XX:MaxGCPauseMillis=5000 Some say below parameter are very optimal -XX:+DisableExplicitGC -XX:+UseConcMarkSweepGC -XX:NewSize=1200m -XX:SurvivorRatio=16 http://www.theserverside.com[..]d.tss?thread_id=41258&ASRC=EM_NNL_347804 Some say those parameter is good -XX:+UseConcMarkSweepGC -XX:ParallelCMSThreads=1 -XX:+CMSIncrementalMode -XX:+CMSIncrementalPacing -XX:CMSIncrementalDutyCycleMin=0 -XX:CMSIncrementalDutyCycle=10 http://blog.mikiobraun.de/2010/08/cassandra-gc-tuning.html Just in case anyone is curious, the flags enabled by -XX:+AggressiveOpts in JDK 1.6.0_25 are: -XX:+EliminateAutoBox -XX:AutoBoxCacheMax=20000 -XX:BiasedLockingStartupDelay=500 -XX:+DoEscapeAnalysis -XX:+OptimizeStringConcat -XX:+OptimizeFill Generate dump with OOME - -XX:+HeapDumpOnOutOfMemoryError GC log sample of -XX:+UseConcMarkSweepGC -XX:PrintFLSStatistics=1 -XX:+PrintGCDetails - https://gist.github.com/1329783 A case study of tuning VM GC parameters - http://plumbr.eu[..]ld-you-trust-the-default-settings-in-jvm
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