From 5836493e8b5ac0ae47e4f5b7fc8ad79efffffb55 Mon Sep 17 00:00:00 2001
From: ym <wazap_by@mail.ru>
Date: Fri, 14 Jan 2022 19:54:15 +0100
Subject: [PATCH] added deadlocks

---
 .../javawebinar/basejava/LazySingleton.java   | 24 +++++++
 .../javawebinar/basejava/MainConcurrency.java | 72 +++++++++++++++++++
 src/ru/javawebinar/basejava/MainDeadlock.java | 50 +++++++++++++
 3 files changed, 146 insertions(+)
 create mode 100644 src/ru/javawebinar/basejava/LazySingleton.java
 create mode 100644 src/ru/javawebinar/basejava/MainConcurrency.java
 create mode 100644 src/ru/javawebinar/basejava/MainDeadlock.java

diff --git a/src/ru/javawebinar/basejava/LazySingleton.java b/src/ru/javawebinar/basejava/LazySingleton.java
new file mode 100644
index 0000000..223ce3f
--- /dev/null
+++ b/src/ru/javawebinar/basejava/LazySingleton.java
@@ -0,0 +1,24 @@
+package ru.javawebinar.basejava;
+
+public class LazySingleton {
+    volatile private static LazySingleton INSTANCE;
+
+    private LazySingleton() {
+    }
+
+    private static class LazySingletonHolder {
+        private static final LazySingleton INSTANCE = new LazySingleton();
+    }
+
+    public static LazySingleton getInstance() {
+        return LazySingletonHolder.INSTANCE;
+//        if (INSTANCE == null) {
+//            synchronized (LazySingleton.class) {
+//                if (INSTANCE == null) {
+//                    INSTANCE = new LazySingleton();
+//                }
+//            }
+//        }
+//        return INSTANCE;
+    }
+}
\ No newline at end of file
diff --git a/src/ru/javawebinar/basejava/MainConcurrency.java b/src/ru/javawebinar/basejava/MainConcurrency.java
new file mode 100644
index 0000000..5c3f347
--- /dev/null
+++ b/src/ru/javawebinar/basejava/MainConcurrency.java
@@ -0,0 +1,72 @@
+package ru.javawebinar.basejava;
+
+import java.util.ArrayList;
+import java.util.List;
+
+public class MainConcurrency {
+    public static final int THREADS_NUMBER = 10000;
+    private int counter;
+    private static final Object LOCK = new Object();
+
+    public static void main(String[] args) throws InterruptedException {
+        System.out.println(Thread.currentThread().getName());
+
+        Thread thread0 = new Thread() {
+            @Override
+            public void run() {
+                System.out.println(getName() + ", " + getState());
+                throw new IllegalStateException();
+            }
+        };
+        thread0.start();
+
+        new Thread(new Runnable() {
+
+            @Override
+            public void run() {
+                System.out.println(Thread.currentThread().getName() + ", " + Thread.currentThread().getState());
+            }
+
+            private void inc() {
+                synchronized (this) {
+//                    counter++;
+                }
+            }
+
+        }).start();
+
+        System.out.println(thread0.getState());
+
+        final MainConcurrency mainConcurrency = new MainConcurrency();
+        List<Thread> threads = new ArrayList<>(THREADS_NUMBER);
+
+        for (int i = 0; i < THREADS_NUMBER; i++) {
+            Thread thread = new Thread(() -> {
+                for (int j = 0; j < 100; j++) {
+                    mainConcurrency.inc();
+                }
+            });
+            thread.start();
+            threads.add(thread);
+        }
+
+        threads.forEach(t -> {
+            try {
+                t.join();
+            } catch (InterruptedException e) {
+                e.printStackTrace();
+            }
+        });
+        System.out.println(mainConcurrency.counter);
+    }
+
+    private synchronized void inc() {
+//        synchronized (this) {
+//        synchronized (MainConcurrency.class) {
+        counter++;
+//                wait();
+//                readFile
+//                ...
+//        }
+    }
+}
diff --git a/src/ru/javawebinar/basejava/MainDeadlock.java b/src/ru/javawebinar/basejava/MainDeadlock.java
new file mode 100644
index 0000000..67713c1
--- /dev/null
+++ b/src/ru/javawebinar/basejava/MainDeadlock.java
@@ -0,0 +1,50 @@
+package ru.javawebinar.basejava;
+
+public class MainDeadlock {
+    public static Object object1 = new Object();
+    public static Object object2 = new Object();
+
+    public static void main(String[] args) {
+        Thread1 thread1 = new Thread1();
+        Thread2 thread2 = new Thread2();
+        thread1.start();
+        thread2.start();
+    }
+
+    public static class Thread1 extends Thread {
+        @Override
+        public void run() {
+            synchronized (object1) {
+                System.out.println("Thread1: Holding object1");
+                try {
+                    Thread.sleep(15000);
+                } catch (InterruptedException e) {
+                }
+                System.out.println("Thread 1: Waiting for lock 2...");
+
+                synchronized (object2) {
+                    System.out.println("Thread 1: Holding lock 1 & 2...");
+                }
+            }
+        }
+    }
+
+
+    public static class Thread2 extends Thread {
+        @Override
+        public void run() {
+            synchronized (object2) {
+                System.out.println("Thread2: Holding object2");
+                try {
+                    Thread.sleep(10000);
+                } catch (InterruptedException e) {
+                }
+                System.out.println("Thread2: Waiting for a lock2....");
+
+                synchronized (object1) {
+                    System.out.println("Thread2: Holding lock 1  and 2 ...");
+                }
+            }
+        }
+    }
+}