feat: 更新 java 示例

dunwu · Sep 2, 2024 · d4a6433 · d4a6433
1 parent de6e74c
commit d4a6433
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diff --git a/codes/bytecode/basics/src/main/java/io/github/dunwu/javacore/bytecode/BaseInterface.java b/codes/bytecode/basics/src/main/java/io/github/dunwu/javacore/bytecode/BaseInterface.java
@@ -0,0 +1,4 @@
+package io.github.dunwu.javacore.bytecode;
+
+public interface BaseInterface {
+}
diff --git a/...avacore-concurrent/src/main/java/io/github/dunwu/javacore/concurrent/error/WrongInit.java b/...avacore-concurrent/src/main/java/io/github/dunwu/javacore/concurrent/error/WrongInit.java
@@ -0,0 +1,29 @@
+package io.github.dunwu.javacore.concurrent.error;
+
+import java.util.HashMap;
+import java.util.Map;
+
+public class WrongInit {
+
+    private Map<Integer, String> students;
+
+    public WrongInit() {
+        new Thread(() -> {
+            students = new HashMap<>();
+            students.put(1, "王小美");
+            students.put(2, "钱二宝");
+            students.put(3, "周三");
+            students.put(4, "赵四");
+        }).start();
+    }
+
+    public Map<Integer, String> getStudents() {
+        return students;
+    }
+
+    public static void main(String[] args) throws InterruptedException {
+        WrongInit demo = new WrongInit();
+        System.out.println(demo.getStudents().get(1));
+    }
+
+}
diff --git a/...acore-concurrent/src/main/java/io/github/dunwu/javacore/concurrent/error/WrongResult.java b/...acore-concurrent/src/main/java/io/github/dunwu/javacore/concurrent/error/WrongResult.java
@@ -0,0 +1,26 @@
+package io.github.dunwu.javacore.concurrent.error;
+
+import io.github.dunwu.javacore.concurrent.annotation.Error;
+
+@Error
+public class WrongResult {
+
+    volatile static int i;
+
+    public static void main(String[] args) throws InterruptedException {
+        Runnable r = () -> {
+            for (int j = 0; j < 10000; j++) {
+                i++;
+            }
+        };
+
+        Thread thread1 = new Thread(r);
+        thread1.start();
+        Thread thread2 = new Thread(r);
+        thread2.start();
+        thread1.join();
+        thread2.join();
+        System.out.println(i);
+    }
+
+}
diff --git a/codes/javacore-jvm/src/main/java/io/github/dunwu/javacore/jvm/error/DirectMemoryOOM.java b/codes/javacore-jvm/src/main/java/io/github/dunwu/javacore/jvm/error/DirectMemoryOOM.java
@@ -0,0 +1,24 @@
+package io.github.dunwu.javacore.jvm.error;
+
+import sun.misc.Unsafe;
+
+import java.lang.reflect.Field;
+
+/**
+ * VM Args：-Xmx20M -XX:MaxDirectMemorySize=10M
+ *
+ * @author zzm
+ */
+public class DirectMemoryOOM {
+
+    private static final int _1MB = 1024 * 1024;
+
+    public static void main(String[] args) throws Exception {
+        Field unsafeField = Unsafe.class.getDeclaredFields()[0];
+        unsafeField.setAccessible(true);
+        Unsafe unsafe = (Unsafe) unsafeField.get(null);
+        while (true) {
+            unsafe.allocateMemory(_1MB);
+        }
+    }
+}
diff --git a/...vacore-jvm/src/main/java/io/github/dunwu/javacore/jvm/error/RuntimeConstantPoolOOM_1.java b/...vacore-jvm/src/main/java/io/github/dunwu/javacore/jvm/error/RuntimeConstantPoolOOM_1.java
@@ -0,0 +1,22 @@
+package io.github.dunwu.javacore.jvm.error;
+
+import java.util.HashSet;
+import java.util.Set;
+
+/**
+ * VM Args：-XX:PermSize=6M -XX:MaxPermSize=6M
+ *
+ * @author zzm
+ */
+public class RuntimeConstantPoolOOM_1 {
+
+    public static void main(String[] args) {
+        // 使用Set保持着常量池引用，避免Full GC回收常量池行为
+        Set<String> set = new HashSet<String>();
+        // 在short范围内足以让6MB的PermSize产生OOM了
+        short i = 0;
+        while (true) {
+            set.add(String.valueOf(i++).intern());
+        }
+    }
+}
diff --git a/...vacore-jvm/src/main/java/io/github/dunwu/javacore/jvm/error/RuntimeConstantPoolOOM_2.java b/...vacore-jvm/src/main/java/io/github/dunwu/javacore/jvm/error/RuntimeConstantPoolOOM_2.java
@@ -0,0 +1,12 @@
+package io.github.dunwu.javacore.jvm.error;
+
+public class RuntimeConstantPoolOOM_2 {
+
+    public static void main(String[] args) {
+        String str1 = new StringBuilder("计算机").append("软件").toString();
+        System.out.println(str1.intern() == str1);
+
+        String str2 = new StringBuilder("ja").append("va").toString();
+        System.out.println(str2.intern() == str2);
+    }
+}
diff --git a/codes/javacore-jvm/src/main/java/io/github/dunwu/javacore/jvm/error/VMStackOOM.java b/codes/javacore-jvm/src/main/java/io/github/dunwu/javacore/jvm/error/VMStackOOM.java
@@ -0,0 +1,32 @@
+package io.github.dunwu.javacore.jvm.error;
+
+/**
+ * VM Args：-Xss2M （这时候不妨设大些，请在32位系统下运行）
+ *
+ * @author zzm
+ */
+public class VMStackOOM {
+
+    private void dontStop() {
+        while (true) {
+        }
+    }
+
+    public void stackLeakByThread() {
+        while (true) {
+            Thread thread = new Thread(new Runnable() {
+                @Override
+                public void run() {
+                    dontStop();
+                }
+            });
+            thread.start();
+        }
+    }
+
+    public static void main(String[] args) throws Throwable {
+        VMStackOOM oom = new VMStackOOM();
+        oom.stackLeakByThread();
+    }
+
+}
diff --git a/...javacore-jvm/src/main/java/io/github/dunwu/javacore/jvm/memory/DirectOutOfMemoryDemo.java b/...javacore-jvm/src/main/java/io/github/dunwu/javacore/jvm/memory/DirectOutOfMemoryDemo.java
@@ -11,8 +11,6 @@
  * <p>
  * VM Args：-verbose:gc -Xmx20M -XX:MaxDirectMemorySize=10M
  * <p>
- * Linux Test Cli: nohup java -verbose:gc -Xmx20M -XX:MaxDirectMemorySize=10M -classpath "target/javacore-jvm-1.0.1.jar:target/lib/*"
- * io.github.dunwu.javacore.jvm.memory.DirectOutOfMemoryDemo >> output.log 2>&1 &
  *
  * @author <a href="mailto:forbreak@163.com">Zhang Peng</a>
  * @since 2019-06-25

diff --git a/...m/memory/GcOverheadLimitExceededDemo.java → ...vm/memory/GcOverheadLimitExceededOOM.java b/...m/memory/GcOverheadLimitExceededDemo.java → ...vm/memory/GcOverheadLimitExceededOOM.java
@@ -14,14 +14,11 @@
  * <p>
  * VM Args: -Xms10M -Xmx10M
  * <p>
- * Linux Test Cli: nohup java -verbose:gc -Xms10M -Xmx10M -XX:+HeapDumpOnOutOfMemoryError -classpath
- * "target/javacore-jvm-1.0.1.jar:target/lib/*" io.github.dunwu.javacore.jvm.memory.GcOverheadLimitExceededDemo >>
- * output.log 2>&1 &
  *
  * @author <a href="mailto:forbreak@163.com">Zhang Peng</a>
  * @since 2019-06-25
  */
-public class GcOverheadLimitExceededDemo {
+public class GcOverheadLimitExceededOOM {
 
     public static void main(String[] args) {
         List<Double> list = new ArrayList<>();

diff --git a/...memory/HeapMemoryLeakMemoryErrorDemo.java → ...avacore/jvm/memory/HeapMemoryLeakOOM.java b/...memory/HeapMemoryLeakMemoryErrorDemo.java → ...avacore/jvm/memory/HeapMemoryLeakOOM.java
@@ -10,14 +10,11 @@
  * <p>
  * VM Args：-verbose:gc -Xms10M -Xmx10M -XX:+HeapDumpOnOutOfMemoryError
  * <p>
- * Linux Test Cli: nohup java -verbose:gc -Xms10M -Xmx10M -XX:+HeapDumpOnOutOfMemoryError -classpath
- * "target/javacore-jvm-1.0.1.jar:target/lib/*" io.github.dunwu.javacore.jvm.memory.HeapMemoryLeakMemoryErrorDemo >>
- * output.log 2>&1 &
  *
  * @author <a href="mailto:forbreak@163.com">Zhang Peng</a>
  * @since 2019-06-25
  */
-public class HeapMemoryLeakMemoryErrorDemo {
+public class HeapMemoryLeakOOM {
 
     public static void main(String[] args) {
         List<OomObject> list = new ArrayList<>();

diff --git a/...emory/HeapMemoryLeakMemoryErrorDemo2.java → ...vacore/jvm/memory/HeapMemoryLeakOOM2.java b/...emory/HeapMemoryLeakMemoryErrorDemo2.java → ...vacore/jvm/memory/HeapMemoryLeakOOM2.java
@@ -12,10 +12,10 @@
  * @author <a href="mailto:forbreak@163.com">Zhang Peng</a>
  * @since 2020-03-09
  */
-public class HeapMemoryLeakMemoryErrorDemo2 {
+public class HeapMemoryLeakOOM2 {
 
     public static void main(String[] args) {
-        HeapMemoryLeakMemoryErrorDemo2 demo = new HeapMemoryLeakMemoryErrorDemo2();
+        HeapMemoryLeakOOM2 demo = new HeapMemoryLeakOOM2();
         System.out.println("往ArrayList中加入30w内容");
         demo.javaHeapSpace(300000);
         demo.memoryTotal();

diff --git a/.../jvm/memory/HeapOutOfMemoryErrorDemo.java → ...vacore/jvm/memory/HeapOutOfMemoryOOM.java b/.../jvm/memory/HeapOutOfMemoryErrorDemo.java → ...vacore/jvm/memory/HeapOutOfMemoryOOM.java
@@ -7,12 +7,11 @@
  * <p>
  * VM Args：-verbose:gc -Xms10M -Xmx10M
  * <p>
- * Linux Test Cli: java -verbose:gc -Xms10M -Xmx10M -cp target/javacore-jvm-1.0.1.jar io.github.dunwu.javacore.jvm.memory.HeapOutOfMemoryErrorDemo
  *
  * @author <a href="mailto:forbreak@163.com">Zhang Peng</a>
  * @since 2019-06-25
  */
-public class HeapOutOfMemoryErrorDemo {
+public class HeapOutOfMemoryOOM {
 
     public static void main(String[] args) {
         Double[] array = new Double[999999999];

diff --git a/...jvm/memory/MethodAreaOutOfMemoryDemo.java → ...wu/javacore/jvm/memory/MethodAreaOOM.java b/...jvm/memory/MethodAreaOutOfMemoryDemo.java → ...wu/javacore/jvm/memory/MethodAreaOOM.java
@@ -11,14 +11,11 @@
  * <li>(JDK8 以前)-XX:PermSize=10m -XX:MaxPermSize=10m</li>
  * <li>(JDK8 及以后)-XX:MetaspaceSize=10m -XX:MaxMetaspaceSize=10m</li>
  * <p>
- * Linux Test Cli: nohup java -verbose:gc -XX:MetaspaceSize=10m -XX:MaxMetaspaceSize=10m -XX:+HeapDumpOnOutOfMemoryError
- * -classpath "target/javacore-jvm-1.0.1.jar:target/lib/*" io.github.dunwu.javacore.jvm.memory.MethodAreaOutOfMemoryDemo
- * >> output.log 2>&1 &
  *
  * @author <a href="mailto:forbreak@163.com">Zhang Peng</a>
  * @since 2019-06-26
  */
-public class MethodAreaOutOfMemoryDemo {
+public class MethodAreaOOM {
 
     public static void main(String[] args) {
         while (true) {

diff --git a/.../jvm/memory/PermOutOfMemoryErrorDemo.java → .../javacore/jvm/memory/PermGenSpaceOOM.java b/.../jvm/memory/PermOutOfMemoryErrorDemo.java → .../javacore/jvm/memory/PermGenSpaceOOM.java
@@ -13,12 +13,11 @@
  * <li>-Xmx100M -XX:MaxPermSize=16M (JDK8 以前版本)</li>
  * <li>-Xmx100M -XX:MaxMetaspaceSize=16M (JDK8 及以后版本)</li>
  * </ul>
- * Linux Test Cli: nohup java -verbose:gc -Xmx100M -XX:MaxMetaspaceSize=16M -XX:+HeapDumpOnOutOfMemoryError -classpath "target/javacore-jvm-1.0.1.jar:target/lib/*" io.github.dunwu.javacore.jvm.memory.PermOutOfMemoryErrorDemo >> output.log 2>&1 &
  *
  * @author <a href="mailto:forbreak@163.com">Zhang Peng</a>
  * @since 2020-03-08
  */
-public class PermOutOfMemoryErrorDemo {
+public class PermGenSpaceOOM {
 
     public static void main(String[] args) throws Exception {
         for (int i = 0; i < 100_000_000; i++) {

diff --git a/...core/jvm/memory/StackOutOfMemoryDemo.java → ...ore/jvm/memory/StackOutOfMemoryError.java b/...core/jvm/memory/StackOutOfMemoryDemo.java → ...ore/jvm/memory/StackOutOfMemoryError.java
@@ -2,29 +2,27 @@
 
 /**
  * 创建线程导致内存溢出（执行要慎重）
- * <p>
+ *
  * VM Args: -Xss512k
- * <p>
- * Linux Test Cli: nohup java -verbose:gc -Xss512k -cp target/javacore-jvm-1.0.1.jar io.github.dunwu.javacore.jvm.memory.StackOutOfMemoryDemo >> output.log 2>&1 &
  *
  * @author <a href="mailto:forbreak@163.com">Zhang Peng</a>
  * @since 2019-06-25
  */
-public class StackOutOfMemoryDemo {
+public class StackOutOfMemoryError {
 
     private volatile int count;
 
     public static void main(String[] args) {
-        StackOutOfMemoryDemo stackOutOfMemoryDemo = new StackOutOfMemoryDemo();
-        stackOutOfMemoryDemo.stackLeakByThread();
+        StackOutOfMemoryError demo = new StackOutOfMemoryError();
+        demo.stackLeakByThread();
     }
 
     public void stackLeakByThread() {
         while (true) {
             Thread thread = new Thread(new Runnable() {
                 @Override
                 public void run() {
-                    StackOutOfMemoryDemo.this.dontStop();
+                    StackOutOfMemoryError.this.dontStop();
                 }
             });
             thread.start();

diff --git a/...avacore/jvm/memory/StackOverflowDemo.java → ...re/jvm/memory/StackOverflowErrorDemo.java b/...avacore/jvm/memory/StackOverflowDemo.java → ...re/jvm/memory/StackOverflowErrorDemo.java
@@ -11,33 +11,28 @@
  * <p>
  * 如果没有一个新的栈帧所需空间，Java 就会抛出 StackOverflowError。
  * <p>
- * VM 参数：
- * <ul>
- * <li>-Xss228k - 设置栈大小为 228k</li>
- * </ul>
- * <p>
- * Linux Test Cli: nohup java -verbose:gc -Xss228k -cp target/javacore-jvm-1.0.1.jar io.github.dunwu.javacore.jvm.memory.StackOverflowDemo >> output.log 2>&1 &
+ * VM 参数：-Xss228k - 设置栈大小为 228k
  *
  * @author <a href="mailto:forbreak@163.com">Zhang Peng</a>
  * @since 2019-06-25
  */
-public class StackOverflowDemo {
+public class StackOverflowErrorDemo {
 
     private int stackLength = 1;
 
+    public void stackLeak() {
+        stackLength++;
+        stackLeak();
+    }
+
     public static void main(String[] args) {
-        StackOverflowDemo obj = new StackOverflowDemo();
+        StackOverflowErrorDemo demo = new StackOverflowErrorDemo();
         try {
-            obj.recursion();
+            demo.stackLeak();
         } catch (Throwable e) {
-            System.out.println("栈深度：" + obj.stackLength);
+            System.out.println("栈深度：" + demo.stackLength);
             e.printStackTrace();
         }
     }
 
-    public void recursion() {
-        stackLength++;
-        recursion();
-    }
-
 }
diff --git a/...vacore/jvm/memory/StackOverflowDemo2.java → ...e/jvm/memory/StackOverflowErrorDemo2.java b/...vacore/jvm/memory/StackOverflowDemo2.java → ...e/jvm/memory/StackOverflowErrorDemo2.java
@@ -1,19 +1,16 @@
 package io.github.dunwu.javacore.jvm.memory;
 
 /**
- * 类成员循环依赖，导致 StackOverflowError。
- * <p>
+ * 类成员循环依赖，导致 StackOverflowError
+ *
  * VM 参数：
- * <ul>
- * <li>-Xss228k - 设置栈大小为 228k</li>
- * </ul>
- * <p>
- * Linux Test Cli: nohup java -verbose:gc -Xss228k -cp target/javacore-jvm-1.0.1.jar io.github.dunwu.javacore.jvm.memory.StackOverflowDemo2 >> output.log 2>&1 &
+ *
+ * -Xss228k - 设置栈大小为 228k
  *
  * @author <a href="mailto:forbreak@163.com">Zhang Peng</a>
  * @since 2019-06-25
  */
-public class StackOverflowDemo2 {
+public class StackOverflowErrorDemo2 {
 
     public static void main(String[] args) {
         A obj = new A();