From b40f301b71f36de6e2e459f8dc8e1f2b3baaccb0 Mon Sep 17 00:00:00 2001
From: yuanguangxin <274841922@qq.com>
Date: Thu, 16 Apr 2020 00:57:33 +0800
Subject: [PATCH] update jvm

---
 .idea/workspace.xml | 80 +++++++++++++++++++++++----------------------
 Rocket.md           |  1 +
 2 files changed, 42 insertions(+), 39 deletions(-)

diff --git a/.idea/workspace.xml b/.idea/workspace.xml
index 42daf74..0d36467 100644
--- a/.idea/workspace.xml
+++ b/.idea/workspace.xml
@@ -3,7 +3,6 @@
   <component name="ChangeListManager">
     <list default="true" id="af7ffdf2-4ddc-4ed6-8222-60ed5acbc2ed" name="Default Changelist" comment="">
       <change beforePath="$PROJECT_DIR$/.idea/workspace.xml" beforeDir="false" afterPath="$PROJECT_DIR$/.idea/workspace.xml" afterDir="false" />
-      <change beforePath="$PROJECT_DIR$/Rocket.md" beforeDir="false" afterPath="$PROJECT_DIR$/Rocket.md" afterDir="false" />
     </list>
     <option name="SHOW_DIALOG" value="false" />
     <option name="HIGHLIGHT_CONFLICTS" value="true" />
@@ -265,24 +264,9 @@
       <workItem from="1585041029099" duration="2193000" />
       <workItem from="1585219892120" duration="917000" />
       <workItem from="1585223904505" duration="7719000" />
-      <workItem from="1585376676883" duration="673000" />
-      <workItem from="1585460780308" duration="4000" />
-      <workItem from="1586005610200" duration="115000" />
-      <workItem from="1586346473200" duration="439000" />
-    </task>
-    <task id="LOCAL-00012" summary="add q94/98/144/145">
-      <created>1581102125245</created>
-      <option name="number" value="00012" />
-      <option name="presentableId" value="LOCAL-00012" />
-      <option name="project" value="LOCAL" />
-      <updated>1581102125245</updated>
-    </task>
-    <task id="LOCAL-00013" summary="update q98">
-      <created>1581156795852</created>
-      <option name="number" value="00013" />
-      <option name="presentableId" value="LOCAL-00013" />
-      <option name="project" value="LOCAL" />
-      <updated>1581156795852</updated>
+      <workItem from="1585376676883" duration="530000" />
+      <workItem from="1585657110826" duration="2824000" />
+      <workItem from="1586968521346" duration="792000" />
     </task>
     <task id="LOCAL-00014" summary="add q110/q450/q701">
       <created>1581270301073</created>
@@ -606,14 +590,28 @@
       <option name="project" value="LOCAL" />
       <updated>1585234195148</updated>
     </task>
-    <task id="LOCAL-00060" summary="add q62">
-      <created>1585377224497</created>
+    <task id="LOCAL-00060" summary="新增JVM性能监控/调优相关">
+      <created>1585657673868</created>
       <option name="number" value="00060" />
       <option name="presentableId" value="LOCAL-00060" />
       <option name="project" value="LOCAL" />
-      <updated>1585377224497</updated>
+      <updated>1585657673869</updated>
+    </task>
+    <task id="LOCAL-00061" summary="update jvm">
+      <created>1585658308922</created>
+      <option name="number" value="00061" />
+      <option name="presentableId" value="LOCAL-00061" />
+      <option name="project" value="LOCAL" />
+      <updated>1585658308922</updated>
     </task>
-    <option name="localTasksCounter" value="61" />
+    <task id="LOCAL-00062" summary="update jvm">
+      <created>1585658338742</created>
+      <option name="number" value="00062" />
+      <option name="presentableId" value="LOCAL-00062" />
+      <option name="project" value="LOCAL" />
+      <updated>1585658338743</updated>
+    </task>
+    <option name="localTasksCounter" value="63" />
     <servers />
   </component>
   <component name="TypeScriptGeneratedFilesManager">
@@ -666,7 +664,6 @@
     </option>
   </component>
   <component name="VcsManagerConfiguration">
-    <MESSAGE value="rename package" />
     <MESSAGE value="update README.md" />
     <MESSAGE value="add q73/q102/q118/q224" />
     <MESSAGE value="add q736" />
@@ -690,8 +687,9 @@
     <MESSAGE value="add q64" />
     <MESSAGE value="add q155" />
     <MESSAGE value="add q61" />
-    <MESSAGE value="add q62" />
-    <option name="LAST_COMMIT_MESSAGE" value="add q62" />
+    <MESSAGE value="新增JVM性能监控/调优相关" />
+    <MESSAGE value="update jvm" />
+    <option name="LAST_COMMIT_MESSAGE" value="update jvm" />
   </component>
   <component name="WindowStateProjectService">
     <state x="320" y="115" key="#Inspections" timestamp="1581061018990">
@@ -706,14 +704,14 @@
       <screen x="0" y="0" width="1440" height="900" />
     </state>
     <state x="533" y="166" key="#com.intellij.ide.util.MemberChooser/0.0.1440.900@0.0.1440.900" timestamp="1578548165321" />
-    <state x="303" y="50" key="CommitChangelistDialog2" timestamp="1585377224334">
+    <state x="303" y="50" key="CommitChangelistDialog2" timestamp="1585658338467">
       <screen x="0" y="0" width="1440" height="900" />
     </state>
-    <state x="303" y="50" key="CommitChangelistDialog2/0.0.1440.900@0.0.1440.900" timestamp="1585377224334" />
-    <state x="143" y="78" width="1152" height="720" key="DiffContextDialog" timestamp="1585232660808">
-      <screen x="0" y="23" width="1440" height="797" />
+    <state x="303" y="50" key="CommitChangelistDialog2/0.0.1440.900@0.0.1440.900" timestamp="1585658338467" />
+    <state x="143" y="78" width="1152" height="720" key="DiffContextDialog" timestamp="1585657797990">
+      <screen x="0" y="0" width="1440" height="900" />
     </state>
-    <state x="143" y="78" width="1152" height="720" key="DiffContextDialog/0.0.1440.900@0.0.1440.900" timestamp="1585232656095" />
+    <state x="143" y="78" width="1152" height="720" key="DiffContextDialog/0.0.1440.900@0.0.1440.900" timestamp="1585657797990" />
     <state x="144" y="78" width="1152" height="720" key="DiffContextDialog/0.23.1440.793@0.23.1440.793" timestamp="1582714686712" />
     <state x="143" y="78" width="1152" height="720" key="DiffContextDialog/0.23.1440.797@0.23.1440.797" timestamp="1585232660808" />
     <state width="1398" height="303" key="GridCell.Tab.0.bottom" timestamp="1585235047508">
@@ -756,34 +754,38 @@
     </state>
     <state width="1398" height="303" key="GridCell.Tab.1.right/0.0.1440.900@0.0.1440.900" timestamp="1585235047510" />
     <state width="1398" height="304" key="GridCell.Tab.1.right/0.23.1440.797@0.23.1440.797" timestamp="1580408030266" />
-    <state x="431" y="173" key="MultipleFileMergeDialog" timestamp="1586346484190">
+    <state x="431" y="173" key="MultipleFileMergeDialog" timestamp="1586968741746">
       <screen x="0" y="0" width="1440" height="900" />
     </state>
-    <state x="431" y="173" key="MultipleFileMergeDialog/0.0.1440.900@0.0.1440.900" timestamp="1586346484190" />
+    <state x="431" y="173" key="MultipleFileMergeDialog/0.0.1440.900@0.0.1440.900" timestamp="1586968741746" />
     <state x="221" y="63" key="SettingsEditor" timestamp="1585223890241">
       <screen x="0" y="0" width="1440" height="900" />
     </state>
     <state x="221" y="63" key="SettingsEditor/0.0.1440.900@0.0.1440.900" timestamp="1585223890241" />
-    <state x="320" y="190" key="Vcs.Push.Dialog.v2" timestamp="1585377225629">
+    <state x="474" y="173" key="VCS.ChangeListViewerDialog" timestamp="1585577172815">
+      <screen x="0" y="0" width="1440" height="900" />
+    </state>
+    <state x="474" y="173" key="VCS.ChangeListViewerDialog/0.0.1440.900@0.0.1440.900" timestamp="1585577172815" />
+    <state x="320" y="190" key="Vcs.Push.Dialog.v2" timestamp="1585658339806">
       <screen x="0" y="0" width="1440" height="900" />
     </state>
-    <state x="320" y="190" key="Vcs.Push.Dialog.v2/0.0.1440.900@0.0.1440.900" timestamp="1585377225629" />
+    <state x="320" y="190" key="Vcs.Push.Dialog.v2/0.0.1440.900@0.0.1440.900" timestamp="1585658339806" />
     <state x="100" y="100" width="1240" height="700" key="com.intellij.history.integration.ui.views.DirectoryHistoryDialog" timestamp="1581744794182">
       <screen x="0" y="23" width="1440" height="797" />
     </state>
     <state x="100" y="100" width="1240" height="700" key="com.intellij.history.integration.ui.views.DirectoryHistoryDialog/0.23.1440.797@0.23.1440.797" timestamp="1581744794182" />
-    <state x="503" y="374" key="com.intellij.openapi.vcs.update.UpdateOrStatusOptionsDialogupdate-v2" timestamp="1586346477174">
+    <state x="503" y="374" key="com.intellij.openapi.vcs.update.UpdateOrStatusOptionsDialogupdate-v2" timestamp="1586968733599">
       <screen x="0" y="0" width="1440" height="900" />
     </state>
-    <state x="503" y="374" key="com.intellij.openapi.vcs.update.UpdateOrStatusOptionsDialogupdate-v2/0.0.1440.900@0.0.1440.900" timestamp="1586346477174" />
+    <state x="503" y="374" key="com.intellij.openapi.vcs.update.UpdateOrStatusOptionsDialogupdate-v2/0.0.1440.900@0.0.1440.900" timestamp="1586968733599" />
     <state x="100" y="100" width="1240" height="700" key="dock-window-1" timestamp="1585037767258">
       <screen x="0" y="23" width="1440" height="797" />
     </state>
     <state x="100" y="100" width="1240" height="700" key="dock-window-1/0.23.1440.797@0.23.1440.797" timestamp="1585037767258" />
-    <state x="378" y="207" width="683" height="486" key="find.popup" timestamp="1586005661030">
+    <state x="378" y="207" width="683" height="486" key="find.popup" timestamp="1582564254151">
       <screen x="0" y="0" width="1440" height="900" />
     </state>
-    <state x="378" y="207" width="683" height="486" key="find.popup/0.0.1440.900@0.0.1440.900" timestamp="1586005661030" />
+    <state x="378" y="207" width="683" height="486" key="find.popup/0.0.1440.900@0.0.1440.900" timestamp="1582564254151" />
     <state x="398" y="248" key="git4idea.merge.GitPullDialog" timestamp="1582971880352">
       <screen x="0" y="0" width="1440" height="900" />
     </state>
diff --git a/Rocket.md b/Rocket.md
index 6c8ac81..9e5f8db 100644
--- a/Rocket.md
+++ b/Rocket.md
@@ -202,6 +202,7 @@ MySQL为了保证ACID中的一致性和持久性，使用了WAL(Write-Ahead Logg
 2. Java虚拟机栈：与程序计数器一样，Java虚拟机栈（Java Virtual Machine Stacks）也是线程私有的，它的生命周期与线程相同。虚拟机栈描述的是Java方法执行的内存模型：每个方法在执行的同时都会创建一个栈帧 ，用于存储局部变量表、操作数栈、动态链接、方法出口等信息。每一个方法从调用直至执行完成的过程，就对应着一个栈帧在虚拟机栈中入栈到出栈的过程。
 3. 本地方法栈：本地方法栈（Native Method Stack）与虚拟机栈所发挥的作用是非常相似的，它们之间的区别不过是虚拟机栈为虚拟机执行Java方法（也就是字节码）服务，而本地方法栈则为虚拟机使用到的Native方法服务。
 4. Java堆：对于大多数应用来说，Java堆是Java虚拟机所管理的内存中最大的一块。Java堆是被所有线程共享的一块内存区域，在虚拟机启动时创建。此内存区域的唯一目的就是存放对象实例，几乎所有的对象实例都在这里分配内存。
+5. 方法区：方法区用于存储已被虚拟机加载的类信息、常量、静态变量，如static修饰的变量加载类的时候就被加载到方法区中。运行时常量池是方法区的一部分，class文件除了有类的字段、接口、方法等描述信息之外，还有常量池用于存放编译期间生成的各种字面量和符号引用。在老版jdk，方法区也被称为永久代。在1.8之后，由于永久代内存经常不够用或发生内存泄露，爆出异常java.lang.OutOfMemoryError，所以在1.8之后废弃永久代，引入元空间的概念。元空间是方法区的在HotSpot jvm 中的实现，元空间的本质和永久代类似，都是对JVM规范中方法区的实现。不过元空间与永久代之间最大的区别在于：元空间并不在虚拟机中，而是使用本地内存。理论上取决于32位/64位系统可虚拟的内存大小。可见也不是无限制的，需要配置参数。
 
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