【正文】 的最迅捷的途徑，是主動承擔(dān)別人都不愿意接手的工作，并在其中展示你出眾的創(chuàng)造力和解決問題的能力?！爆F(xiàn)實中那些頂尖的成功人士不是成功了才設(shè)定目標，而是設(shè)定了目標才成功。 JIT 編譯器能部分或者全部把程序轉(zhuǎn)換成機器能夠識別的代碼，所以程序就不需要 JVM 的解釋了，結(jié)果是程序運行起來快很多。 這種方式解決了通常情況下許多短期生存的暫時對象。相反，當內(nèi)存閑置空間少的時候，Sun 的垃圾收集器會終止程序運行。 處理一般的垃圾收集工作，markandsweep 表現(xiàn)得相當?shù)芈?，但是當你的程序生成很少或者不生成垃圾時，它又運行得很快。有兩個問題使這種所謂的“拷貝型收集器”缺乏效率。其中的一個變體就是 stopandcopy。有一種執(zhí)行更快的垃圾收集方案，這種方案中垃圾收集不是建立在引用記數(shù)的基礎(chǔ)上。 一種簡單的但卻較慢的垃圾收集技術(shù)就是引用記數(shù)（reference counting）。 這就意味著對象存貯空間的分配速度明顯加快。 Cleanup that will be encountered later during the “walk.” These are fixed up as they are found (you could imagine a table that maps old addresses to new ones).There are two issues that make these socalled “copy collectors” inefficient. The first is the idea that you have two heaps and you slosh all the memory back and forth between these two separate heaps, maintaining twice as much memory as you actually need. Some JVMs deal with this by allocating the heap in chunks as needed and simply copying from one chunk to another.The second issue is the copying process itself. Once your program bees stable, it might be generating little or no garbage. Despite that, a copy collector will still copy all the memory from one place to another, which is wasteful. To prevent this, some JVMs detect that no new garbage is being generated and switch to a different scheme (this is the “adaptive” part). This other scheme is called markandsweep, and it’s what earlier versions of Sun’s JVM used all the time. For general use, markandsweep is fairly slow, but when you know you’re generating little or no garbage, it’s fast. Markandsweep follows the same logic of starting from the stack and static storage, and tracing through all the references to find live objects. However, each time it finds a live object, that object is marked by setting a flag in it, but the object isn’t collected yet. Only when the marking process is finished does the sweep occur. During the sweep, the dead objects are released. However, no copying happens, so if the collector chooses to pact a fragmented heap, it does so by shuffling objects around. “Stopandcopy” refers to the idea that this type of garbage collection is not done in the background。 and it increases the size of the executable (byte codes are significantly more pact than expanded JIT code), and this might cause paging, which definitely slows down a program. An alternative approach is lazy evaluation, which means that the code is not JIT piled until necessary. Thus, code that never gets executed might never be JIT piled. The Java Hotspot technologies in recent JDKs take a similar approach by increasingly optimizing a piece of code each time it is executed, so the more the code is executed, the faster it gets.Java垃圾收集器的工作方式 如果你學(xué)下過一種因為在堆里分配對象所以開銷過大的編程語言，很自然你可能會假定 Java 在堆里為每一樣?xùn)|西（除了 primitives）分配內(nèi)存資源的機制開銷也會很大。）你或許觀察到實際上堆本身并不是一個傳送帶，如果你真的那樣看待堆，你就會啟用虛擬內(nèi)存——在硬盤里不斷地裝卸，結(jié)果是看上去你會擁有比實際情況還要多的內(nèi)存空間。垃圾收集器歷遍整組對象，當它發(fā)現(xiàn)一個引用記數(shù)為零的對象時就會釋放那個對象的存貯空間。因此，如果從棧和靜態(tài)存貯器里開始并歷遍整個引用組，你會找到所有存活的對象。并且，當對象被拷貝到新的堆里后，他們在那里被一個挨一個塞緊，因此實現(xiàn)了壓縮新堆的目的（而且如前所述，這種方式騰出了壓縮后多余出來的新的空間）。第二個問題是拷貝過程本身。 只有在整個標記過程完成后，清掃（sweep）工作才真正開始。 如果你指定了一個大的對象，它將會得到它自己的內(nèi)存塊。 JVM 會監(jiān)視垃圾收集的效率，如果是因為所有的對象都穩(wěn)定運行而使得收集工作比較浪費時間的話，垃圾收集會轉(zhuǎn)向 markandsweep 模式。一個替代方案就是 lazy evaluation，它的意思是直到代碼需要的時候，才用 JIT 來編譯。相反，如果他抓住了主要矛盾，解決問題就變得容易多了。要事第一創(chuàng)設(shè)遍及全美的事務(wù)公司的亨瑞。凡事在事業(yè)上有所成就的人，幾乎都是能有效地利用零碎時間的人。習(xí)慣1換位思考在人際的相處和溝通里，“換位思考”扮演著相當重要的角色。不斷學(xué)習(xí)一個人,如果每天都能提高1%,很多時候,它們之間的區(qū)別就在于你是否每天都在提高你自己。善于傾聽，是一個高效能人士的一項最基本的素質(zhì)。在紛繁復(fù)雜的現(xiàn)代社會，只有保持內(nèi)心平靜的人，才能保證身體健康和高效能的工作。注重準備工作一個善于做準備的人，是距離成功最近的人。結(jié)果發(fā)現(xiàn)，大家認同的杰出人物，其核心能力并不是他的專業(yè)優(yōu)勢，相反，出色的人際策略卻是他們成功的關(guān)鍵歷練說話技巧有人說：“眼睛可以容納一個美麗的世界，而嘴巴則能