缓缓琢磨JVM——恭喜JavaEye重新开张

慢慢琢磨JVM——恭喜JavaEye重新开张

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?该图参考了网上广为流传的JVM构成图，大家看这个图，整个JVM分为四部分：

?图示在一个栈中有两个栈帧，栈帧2是最先被调用的方法，先入栈，然后方法2又调用了方法1，栈帧1处于栈顶的位置，栈帧2处于栈底，执行完毕后，依次弹出栈帧1和栈帧2，线程结束，栈释放。

?q?Method Area 方法区

（引用自《虚拟机：系统与进程的通用平台》第一章）

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<p alt="缓缓琢磨JVM——恭喜JavaEye重新开张"><br>?<span>该图参考了网上广为流传的<span lang="EN-US">JVM</span>构成图，大家看这个图，整个<span lang="EN-US">JVM</span>分为四部分：</span></p>
<p style="margin-right: 0cm; text-indent: 17.5pt;"><span style="color: windowtext; font-size: 10pt;"><span>??? </span>ClassFile {</span></p>
<p style="margin-right: 0cm; text-indent: 17.5pt;"><span style="color: windowtext; font-size: 10pt;"><span>??? </span><span>? </span>u4 magic;</span></p>
<p style="margin-right: 0cm; text-indent: 17.5pt;"><span style="color: windowtext; font-size: 10pt;"><span>??? </span><span>? </span>u2 minor_version;</span></p>
<p style="margin-right: 0cm; text-indent: 17.5pt;"><span style="color: windowtext; font-size: 10pt;"><span>?</span><span>?? </span><span>? </span>u2 major_version;</span></p>
<p style="margin-right: 0cm; text-indent: 17.5pt;"><span style="color: windowtext; font-size: 10pt;"><span>??? </span><span>? </span>u2 constant_pool_count;</span></p>
<p style="margin-right: 0cm; text-indent: 17.5pt;"><span style="color: windowtext; font-size: 10pt;"><span>??? </span><span>? </span>cp_info constant_pool[constant_pool_count-1];</span></p>
<p style="margin-right: 0cm; text-indent: 17.5pt;"><span style="color: windowtext; font-size: 10pt;"><span>??? </span><span>? </span>u2 access_flags;</span></p>
<p style="margin-right: 0cm; text-indent: 17.5pt;"><span style="color: windowtext; font-size: 10pt;"><span>??? </span><span>? </span>u2 this_class;</span></p>
<p style="margin-right: 0cm; text-indent: 17.5pt;"><span style="color: windowtext; font-size: 10pt;"><span>??? </span><span>? </span>u2 super_class;</span></p>
<p style="margin-right: 0cm; text-indent: 17.5pt;"><span style="color: windowtext; font-size: 10pt;"><span>??? </span><span>? </span>u2 interfaces_count;</span></p>
<p style="margin-right: 0cm; text-indent: 17.5pt;"><span style="color: windowtext; font-size: 10pt;"><span>??? </span><span>? </span>u2 interfaces[interfaces_count];</span></p>
<p style="margin-right: 0cm; text-indent: 17.5pt;"><span style="color: windowtext; font-size: 10pt;"><span>??? </span><span>? </span>u2 fields_count;</span></p>
<p style="margin-right: 0cm; text-indent: 17.5pt;"><span style="color: windowtext; font-size: 10pt;"><span>??? </span><span>? </span>field_info fields[fields_count];</span></p>
<p style="margin-right: 0cm; text-indent: 17.5pt;"><span style="color: windowtext; font-size: 10pt;"><span>??? </span><span>? </span>u2 methods_count;</span></p>
<p style="margin-right: 0cm; text-indent: 17.5pt;"><span style="color: windowtext; font-size: 10pt;"><span>??? </span><span>? </span>method_info methods[methods_count];</span></p>
<p style="margin-right: 0cm; text-indent: 17.5pt;"><span style="color: windowtext; font-size: 10pt;"><span>??? </span><span>? </span>u2 attributes_count;</span></p>
<p style="margin-right: 0cm; text-indent: 17.5pt;"><span style="color: windowtext; font-size: 10pt;"><span>??? </span><span>? </span>attribute_info attributes[attributes_count];</span></p>
<p style="margin-right: 0cm; text-indent: 17.5pt;"><span style="color: windowtext; font-size: 10pt;"><span>??? </span>}</span></p>
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<p alt="缓缓琢磨JVM——恭喜JavaEye重新开张"><br>?<span>图示在一个栈中有两个栈帧，栈帧<span lang="EN-US">2</span>是最先被调用的方法，先入栈，然后方法<span lang="EN-US">2</span>又调用了方法<span lang="EN-US">1</span>，栈帧<span lang="EN-US">1</span>处于栈顶的位置，栈帧<span lang="EN-US">2</span>处于栈底，执行完毕后，依次弹出栈帧<span lang="EN-US">1</span>和栈帧<span lang="EN-US">2</span>，线程结束，栈释放。</span></p>
<p style="text-indent: 21.1pt;"><strong><span lang="EN-US">Permanent Space </span></strong><strong><span>永久存储区</span></strong></p>
<p style="text-indent: 21.1pt;"><strong><span lang="EN-US">Young Generation Space </span></strong><strong><span>新生区</span></strong></p>
<p style="text-indent: 21.1pt;"><strong><span lang="EN-US">Tenure generation space</span></strong><strong><span>养老区</span></strong></p>
<p alt="缓缓琢磨JVM——恭喜JavaEye重新开张"><br>?<span style="font-family: Wingdings;"><span>q<span style="font: 7.0pt ;">? </span></span></span><span lang="EN-US">Method Area </span><span>方法区</span></p>
<p style="text-indent: 21.1pt;"><strong><span>问：堆和栈有什么区别</span></strong></p>
<p style="text-indent: 21.1pt;"><strong><span>问：堆内存中到底存在着什么东西？</span></strong></p>
<p style="text-indent: 21.1pt;"><strong><span>问：类变量和实例变量有什么区别？</span></strong></p>
<p style="text-indent: 21.1pt;"><strong><span>问：我听说类变量是在</span><span lang="EN-US">JVM</span></strong><strong><span>启动时就初始化好的，和你这说的不同呀！</span></strong></p>
<p style="text-indent: 21.1pt;"><strong><span>问：</span><span lang="EN-US">Java</span></strong><strong><span>的方法（函数）到底是传值还是传址？</span></strong></p>
<p style="text-indent: 21.1pt;"><strong><span>问：为什么会产生</span><span lang="EN-US">OutOfMemory</span></strong><strong><span>产生？</span></strong></p>
<p style="text-indent: 21.1pt;"><strong><span>问：我产生的对象不多呀，为什么还会产生</span><span lang="EN-US">OutOfMemory</span></strong><strong><span>？</span></strong></p>
<p style="text-indent: 21.1pt;"><strong><span>问：</span><span lang="EN-US">OutOfMemory</span></strong><strong><span>错误分几种？</span></strong></p>
<p style="text-indent: 21.1pt;"><strong><span>问：为什么会产生</span><span lang="EN-US">StackOverflowError</span></strong><strong><span>？</span></strong></p>
<p style="text-indent: 21.1pt;"><strong><span>问：一个机器上可以看多个</span><span lang="EN-US">JVM</span></strong><strong><span>吗？</span><span lang="EN-US">JVM</span></strong><strong><span>之间可以互访吗？</span></strong></p>
<p style="text-indent: 21.1pt;"><strong><span>问：为什么</span><span lang="EN-US">Java</span></strong><strong><span>要采用垃圾回收机制，而不采用</span><span lang="EN-US">C/C++</span></strong><strong><span>的显式内存管理？</span></strong></p>
<p style="text-indent: 21.1pt;"><strong><span>问：为什么你没有详细介绍垃圾回收机制？</span></strong></p>
<p style="text-indent: 21.1pt;"><strong><span>问：</span><span lang="EN-US">JVM</span></strong><strong><span>中到底哪些区域是共享的？哪些是私有的？</span></strong></p>
<p style="text-indent: 21.1pt;"><strong><span>问：什么是</span><span lang="EN-US">JIT</span></strong><strong><span>，你怎么没说？</span></strong></p>
<p style="text-indent: 21.1pt;"><strong><span>问：</span><span lang="EN-US">JVM</span></strong><strong><span>还有哪些部分是你没有提到的？</span></strong></p>
<p style="text-indent: 0cm;"><span lang="EN-US"><span>?????? </span></span></p>
<p style="text-indent: 21.1pt;"><strong><span>问：为什么不建议在程序中显式的生命</span><span lang="EN-US">System.gc()</span></strong><strong><span>？</span></strong></p>
<p style="text-indent: 21.1pt;"><strong><span>问：</span><span lang="EN-US">JVM</span></strong><strong><span>有哪些调整参数？</span></strong></p>
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