java虚拟机开始学习

chenzhuo@picooc.com · chenzhuo@picooc.com · commit 42aff276354e · 2019-01-09T23:19:16.000+08:00
diff --git a/src/main/java/com/basics/enumTest/EmuTest.java b/src/main/java/com/basics/enumTest/EmuTest.java
@@ -0,0 +1,23 @@
+package com.basics.enumTest;
+
+/**
+ * @ClassName EmuTest
+ * @Despacito TODO
+ * @Author chenzhuo
+ * @Version 1.0
+ **/
+public class   EmuTest {
+    public static void main(String[] args) {
+        String s = Test.emmm.valaue;
+    }
+    enum  Test{
+        emmm("这是一个枚举类");
+        public String valaue;
+        Test(String valaue){
+            this.valaue =valaue;
+        }
+        public String getValaue(){
+            return valaue;
+        }
+    }
+}
diff --git a/src/main/java/com/sun/jvm/Jvm/PretenureSizeThresholdTest/PretenureSizeThreshold.java b/src/main/java/com/sun/jvm/Jvm/PretenureSizeThresholdTest/PretenureSizeThreshold.java
@@ -0,0 +1,20 @@
+package com.sun.jvm.Jvm.PretenureSizeThresholdTest;
+
+/**
+ * @ClassName PretenureSizeThreshold
+ * @Despacito TODO
+ * @Author chenzhuo
+ * @Version 1.0
+ * -verbose:gc-Xms20M-Xmx20M-Xmn10M-XX:+PrintGCDetails-XX:SurvivorRatio=8
+ *
+ * **-XX:PretenureSizeThreshold=3145728
+ **/
+public class PretenureSizeThreshold {
+
+    public static void main(String[] args) {
+    }
+    public static void testPretenureSizeThreshold(){
+        byte[] a ;
+        a = new byte[4*1024];
+    }
+}
diff --git a/src/main/java/com/sun/jvm/Jvm/finalize/FinalizeEscapeGC.java b/src/main/java/com/sun/jvm/Jvm/finalize/FinalizeEscapeGC.java
@@ -5,8 +5,6 @@
  * @Despacito TODO
  * @Author chenzhuo
  * @Version 1.0
- *
- *
  * Finalize导致gc失效
  * finalize 放在 finalize-Queue中 在一个低级的线程中执行
  * finalize() 只能被执行一次
@@ -35,6 +33,8 @@
  *  finalize-Queue是由一个低级的线程去执行的,jvm不保证这个一定会执行完,
  *  因为finalize-Queue在执行的时候可能出现了死循环,会导致整个回收系统的奔溃
  *
+ *
+ *
  **/
 public class FinalizeEscapeGC {
     public static FinalizeEscapeGC SAVE_HOOK = null;
diff --git a/src/main/java/com/sun/jvm/Jvm/gcRoots/GCRootTest.java b/src/main/java/com/sun/jvm/Jvm/gcRoots/GCRootTest.java
@@ -68,6 +68,8 @@ public static void main(String[] args) {
             Node node = new Node(i, next);
             next = node;
         }
+        next = null;
+        triggerGC();
         /**
          *  gc日志
          * [GC (Allocation Failure) [ParNew: 1064551K->847K(1198080K), 0.0038396 secs] 1064551K->847K(3962880K), 0.0039093 secs] [Times: user=0.00 sys=0.00, real=0.00 secs]
@@ -83,7 +85,7 @@ public static void main(String[] args) {
         //没有设置为null的时候,回收的时候会遍历next的所以节点,所以会很耗时间
         //但是把next的set为null的时候 就变为不可达状态
        // next = null; help gc
-        triggerGC();
+
     }
 
     private static void triggerGC() {
