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But it’s not a big deal, because the clear() and addAll(collection) methods are quite fast, as we saw in our first charts, and they are definitely faster than some other O(n) or O(n x n) operations on some collections. So it’s faster to recreate from scratch the all collection than applying a remove(Object) on an Ar... 阅205 转0 评0 公众公开 11-10-12 11:34 |
While Garbage Collection is executed in the permanent generation, it only happens during a major GC. You might want to read up what a Major GC actually is, as it does not mean a Old Generation GC. Because a major GC does not happen often and mostly nothing happens in the permanent generation, many people think that th... 阅153 转6 评0 公众公开 11-10-12 11:34 |
Hunt recommends using it over -XX:AggressiveHeap. -XX:+UseBiasedLocking, -XX:+DoEscapeAnalysis, -XX:+AlwaysPreTouch,-XX:+PrintCommandLineFlags, and -XX:+PrintFlagsFinal were all also part of the "Other" secton. -XX:+PrintcommandLineFlags shows the ergonomically selected options for a JVM and -XX:+PrintFlagsF... 阅144 转0 评0 公众公开 11-10-12 11:31 |
Pick up performance with generational garbage collectionPick up performance with generational garbage collectionUse the appropriate Java HotSpot VM 1.3.1 parameters to improve throughput.Poorly selected JVM parameters can severely degrade your application performance.The HotSpot JVM''s tunable parameters let y... 阅101 转1 评0 公众公开 11-10-10 16:08 |
阅2334 转1 评0 公众公开 11-10-10 15:58 |
JIT编译器将字节码编译成本机机器代码。在运行时JIT会把翻译过的机器码保存起来，已备下次使用，因此从理论上来说，采用该JIT技术可以，可以接近以前纯编译技术。JIT并不总是奏效，不能期望JIT一定能够加速你代码执行的速度，更糟糕的是她有可能降低代码的执行速度。由于JIT对每条字节码都进行编译，造成了编译过程负担过重。 阅387 转3 评0 公众公开 11-09-15 17:15 |
