it_worker365

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1. 启动netty server 等待接受客户端连接

 1 package io.netty.example.myTest.nio;
 2 import java.io.IOException;
 3 import java.net.InetSocketAddress;
 4 import java.nio.channels.SelectionKey;
 5 import java.nio.channels.Selector;
 6 import java.nio.channels.ServerSocketChannel;
 7 import java.util.Iterator;
 8 import java.util.Set;
 9 
10 public class ServerNIO {
11     static Selector selector;
12     static ServerSocketChannel serverSocketChannel;
13     public static void main (String[] args) {
14         try {
15             selector = Selector.open();
16             serverSocketChannel = ServerSocketChannel.open();
17             serverSocketChannel.socket().bind(new InetSocketAddress("localhost", 9999));
18             serverSocketChannel.configureBlocking(false);
19             SelectionKey selectionKey = serverSocketChannel.register(selector, SelectionKey.OP_ACCEPT);
20             while ( true ) {
21                 selector.select(1000);
22                 Set<SelectionKey> keys = selector.selectedKeys();
23                 Iterator<SelectionKey> iKeys = keys.iterator();
24                 SelectionKey selectionKey1 = null;
25                 while (iKeys.hasNext()) {
26                     selectionKey1 = iKeys.next();
27                     iKeys.remove();
28                     if (selectionKey1.isValid()) {
29                         if (selectionKey1.isAcceptable()) {
30                             Thread.sleep(10000);
31                             System.out.println("accept");
32                         }
33                     }
34                 }
35             }
36         }catch (IOException ioe) {
37 
38         } catch (InterruptedException e) {
39             e.printStackTrace();
40         }
41     }
42 }

jps 查看进程号

jstack查看进程状态,处于RUNNABLE 并在ServerNIO.main(ServerNIO.java:21) 处,调用栈看到 EPollArrayWrapper.epollWait

[root@izm5e8p93wtcdi53pzqhi7z ~]# jstack 29266

2018-07-30 13:06:39
Full thread dump Java HotSpot(TM) 64-Bit Server VM (25.181-b13 mixed mode):

"Attach Listener" #8 daemon prio=9 os_prio=0 tid=0x00007f2e28001000 nid=0x7289 waiting on condition [0x0000000000000000]
   java.lang.Thread.State: RUNNABLE

"Service Thread" #7 daemon prio=9 os_prio=0 tid=0x00007f2e580ba000 nid=0x725c runnable [0x0000000000000000]
   java.lang.Thread.State: RUNNABLE

"C1 CompilerThread1" #6 daemon prio=9 os_prio=0 tid=0x00007f2e580b7000 nid=0x725b waiting on condition [0x0000000000000000]
   java.lang.Thread.State: RUNNABLE

"C2 CompilerThread0" #5 daemon prio=9 os_prio=0 tid=0x00007f2e580b4000 nid=0x725a waiting on condition [0x0000000000000000]
   java.lang.Thread.State: RUNNABLE

"Signal Dispatcher" #4 daemon prio=9 os_prio=0 tid=0x00007f2e580b2800 nid=0x7259 runnable [0x0000000000000000]
   java.lang.Thread.State: RUNNABLE

"Finalizer" #3 daemon prio=8 os_prio=0 tid=0x00007f2e5807f800 nid=0x7258 in Object.wait() [0x00007f2e5c4de000]
   java.lang.Thread.State: WAITING (on object monitor)
        at java.lang.Object.wait(Native Method)
        - waiting on <0x00000000f6708ed0> (a java.lang.ref.ReferenceQueue$Lock)
        at java.lang.ref.ReferenceQueue.remove(ReferenceQueue.java:144)
        - locked <0x00000000f6708ed0> (a java.lang.ref.ReferenceQueue$Lock)
        at java.lang.ref.ReferenceQueue.remove(ReferenceQueue.java:165)
        at java.lang.ref.Finalizer$FinalizerThread.run(Finalizer.java:216)

"Reference Handler" #2 daemon prio=10 os_prio=0 tid=0x00007f2e5807d000 nid=0x7257 in Object.wait() [0x00007f2e5c5df000]
   java.lang.Thread.State: WAITING (on object monitor)
        at java.lang.Object.wait(Native Method)
        - waiting on <0x00000000f6706bf8> (a java.lang.ref.Reference$Lock)
        at java.lang.Object.wait(Object.java:502)
        at java.lang.ref.Reference.tryHandlePending(Reference.java:191)
        - locked <0x00000000f6706bf8> (a java.lang.ref.Reference$Lock)
        at java.lang.ref.Reference$ReferenceHandler.run(Reference.java:153)

"main" #1 prio=5 os_prio=0 tid=0x00007f2e58009000 nid=0x7253 runnable [0x00007f2e61a9a000]
   java.lang.Thread.State: RUNNABLE
        at sun.nio.ch.EPollArrayWrapper.epollWait(Native Method)
        at sun.nio.ch.EPollArrayWrapper.poll(EPollArrayWrapper.java:269)
        at sun.nio.ch.EPollSelectorImpl.doSelect(EPollSelectorImpl.java:93)
        at sun.nio.ch.SelectorImpl.lockAndDoSelect(SelectorImpl.java:86)
        - locked <0x00000000f6775890> (a sun.nio.ch.Util$3)
        - locked <0x00000000f6775808> (a java.util.Collections$UnmodifiableSet)
        - locked <0x00000000f6770c10> (a sun.nio.ch.EPollSelectorImpl)
        at sun.nio.ch.SelectorImpl.select(SelectorImpl.java:97)
        at ServerNIO.main(ServerNIO.java:21)

"VM Thread" os_prio=0 tid=0x00007f2e58073000 nid=0x7256 runnable

"GC task thread#0 (ParallelGC)" os_prio=0 tid=0x00007f2e5801e800 nid=0x7254 runnable

"GC task thread#1 (ParallelGC)" os_prio=0 tid=0x00007f2e58020000 nid=0x7255 runnable

"VM Periodic Task Thread" os_prio=0 tid=0x00007f2e580be800 nid=0x725d waiting on condition

JNI global references: 14

2. 启动一个客户端,仅连接

package io.netty.example.myTest.nio;

import java.io.IOException;
import java.net.InetSocketAddress;
import java.nio.channels.SelectionKey;
import java.nio.channels.Selector;
import java.nio.channels.ServerSocketChannel;
import java.nio.channels.SocketChannel;
import java.util.Iterator;
import java.util.Set;

public class ClientNIO {
    static Selector selector;
    static SocketChannel socketChannel;
    public static void main (String[] args) {
        try {
            socketChannel = SocketChannel.open();
            socketChannel.connect(new InetSocketAddress("localhost", 9999));
        }catch (IOException ioe) {

        }
    }
}

连接后断开,再次运行[root@izm5e8p93wtcdi53pzqhi7z ~]# jstack 29266,可以看到ServerNIO.main(ServerNIO.java:30)  此时已经连接并且在sleep,java.lang.Thread.State: TIMED_WAITING (sleeping)

2018-07-30 13:20:08
Full thread dump Java HotSpot(TM) 64-Bit Server VM (25.181-b13 mixed mode):

"Attach Listener" #8 daemon prio=9 os_prio=0 tid=0x00007f2e28001000 nid=0x7289 waiting on condition [0x0000000000000000]
   java.lang.Thread.State: RUNNABLE

"Service Thread" #7 daemon prio=9 os_prio=0 tid=0x00007f2e580ba000 nid=0x725c runnable [0x0000000000000000]
   java.lang.Thread.State: RUNNABLE

"C1 CompilerThread1" #6 daemon prio=9 os_prio=0 tid=0x00007f2e580b7000 nid=0x725b waiting on condition [0x0000000000000000]
   java.lang.Thread.State: RUNNABLE

"C2 CompilerThread0" #5 daemon prio=9 os_prio=0 tid=0x00007f2e580b4000 nid=0x725a waiting on condition [0x0000000000000000]
   java.lang.Thread.State: RUNNABLE

"Signal Dispatcher" #4 daemon prio=9 os_prio=0 tid=0x00007f2e580b2800 nid=0x7259 runnable [0x0000000000000000]
   java.lang.Thread.State: RUNNABLE

"Finalizer" #3 daemon prio=8 os_prio=0 tid=0x00007f2e5807f800 nid=0x7258 in Object.wait() [0x00007f2e5c4de000]
   java.lang.Thread.State: WAITING (on object monitor)
        at java.lang.Object.wait(Native Method)
        - waiting on <0x00000000f6708ed0> (a java.lang.ref.ReferenceQueue$Lock)
        at java.lang.ref.ReferenceQueue.remove(ReferenceQueue.java:144)
        - locked <0x00000000f6708ed0> (a java.lang.ref.ReferenceQueue$Lock)
        at java.lang.ref.ReferenceQueue.remove(ReferenceQueue.java:165)
        at java.lang.ref.Finalizer$FinalizerThread.run(Finalizer.java:216)

"Reference Handler" #2 daemon prio=10 os_prio=0 tid=0x00007f2e5807d000 nid=0x7257 in Object.wait() [0x00007f2e5c5df000]
   java.lang.Thread.State: WAITING (on object monitor)
        at java.lang.Object.wait(Native Method)
        - waiting on <0x00000000f6706bf8> (a java.lang.ref.Reference$Lock)
        at java.lang.Object.wait(Object.java:502)
        at java.lang.ref.Reference.tryHandlePending(Reference.java:191)
        - locked <0x00000000f6706bf8> (a java.lang.ref.Reference$Lock)
        at java.lang.ref.Reference$ReferenceHandler.run(Reference.java:153)

"main" #1 prio=5 os_prio=0 tid=0x00007f2e58009000 nid=0x7253 waiting on condition [0x00007f2e61a9a000]
   java.lang.Thread.State: TIMED_WAITING (sleeping)
        at java.lang.Thread.sleep(Native Method)
        at ServerNIO.main(ServerNIO.java:30)

"VM Thread" os_prio=0 tid=0x00007f2e58073000 nid=0x7256 runnable

"GC task thread#0 (ParallelGC)" os_prio=0 tid=0x00007f2e5801e800 nid=0x7254 runnable

"GC task thread#1 (ParallelGC)" os_prio=0 tid=0x00007f2e58020000 nid=0x7255 runnable

"VM Periodic Task Thread" os_prio=0 tid=0x00007f2e580be800 nid=0x725d waiting on condition

JNI global references: 14

 3. CPU过高(忙于计算,忙于GC - https://www.jianshu.com/p/f93b6013b965)

忙于死循环类测试

 1 package io.netty.example.myTest;
 2 
 3 import java.util.concurrent.ExecutorService;
 4 import java.util.concurrent.Executors;
 5 
 6 public class ThreadTest {
 7     public static void main (String[] args) {
 8         ExecutorService executorService = Executors.newSingleThreadExecutor();
 9         executorService.execute(new Runnable() {
10             @Override
11             public void run() {
12                 int i = 0;
13                 while ( true ) {
14                     i++;
15                     i--;
16                 }
17             }
18         });
19     }
20 }

top -Hp 29926

printf %x 29938  ==》 74f2, 根据该线程号可以找到nid=0x74f2的信息,进而看到 ThreadTest$1.run(ThreadTest.java:13)

2018-07-30 13:41:00
Full thread dump Java HotSpot(TM) 64-Bit Server VM (25.181-b13 mixed mode):

"Attach Listener" #10 daemon prio=9 os_prio=0 tid=0x00007fcdc4001000 nid=0x7519 waiting on condition [0x0000000000000000]
   java.lang.Thread.State: RUNNABLE

"DestroyJavaVM" #9 prio=5 os_prio=0 tid=0x00007fcdfc009000 nid=0x74e7 waiting on condition [0x0000000000000000]
   java.lang.Thread.State: RUNNABLE

"pool-1-thread-1" #8 prio=5 os_prio=0 tid=0x00007fcdfc0ef800 nid=0x74f2 runnable [0x00007fcde75f4000]
   java.lang.Thread.State: RUNNABLE
        at ThreadTest$1.run(ThreadTest.java:13)
        at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149)
        at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
        at java.lang.Thread.run(Thread.java:748)

"Service Thread" #7 daemon prio=9 os_prio=0 tid=0x00007fcdfc0c2000 nid=0x74f0 runnable [0x0000000000000000]
   java.lang.Thread.State: RUNNABLE

"C1 CompilerThread1" #6 daemon prio=9 os_prio=0 tid=0x00007fcdfc0b7000 nid=0x74ef waiting on condition [0x0000000000000000]
   java.lang.Thread.State: RUNNABLE

"C2 CompilerThread0" #5 daemon prio=9 os_prio=0 tid=0x00007fcdfc0b4000 nid=0x74ee waiting on condition [0x0000000000000000]
   java.lang.Thread.State: RUNNABLE

"Signal Dispatcher" #4 daemon prio=9 os_prio=0 tid=0x00007fcdfc0b2800 nid=0x74ed runnable [0x0000000000000000]
   java.lang.Thread.State: RUNNABLE

"Finalizer" #3 daemon prio=8 os_prio=0 tid=0x00007fcdfc07f800 nid=0x74ec in Object.wait() [0x00007fcde7bfa000]
   java.lang.Thread.State: WAITING (on object monitor)
        at java.lang.Object.wait(Native Method)
        - waiting on <0x00000000f6708ed0> (a java.lang.ref.ReferenceQueue$Lock)
        at java.lang.ref.ReferenceQueue.remove(ReferenceQueue.java:144)
        - locked <0x00000000f6708ed0> (a java.lang.ref.ReferenceQueue$Lock)
        at java.lang.ref.ReferenceQueue.remove(ReferenceQueue.java:165)
        at java.lang.ref.Finalizer$FinalizerThread.run(Finalizer.java:216)

"Reference Handler" #2 daemon prio=10 os_prio=0 tid=0x00007fcdfc07d000 nid=0x74eb in Object.wait() [0x00007fcde7cfb000]
   java.lang.Thread.State: WAITING (on object monitor)
        at java.lang.Object.wait(Native Method)
        - waiting on <0x00000000f6706bf8> (a java.lang.ref.Reference$Lock)
        at java.lang.Object.wait(Object.java:502)
        at java.lang.ref.Reference.tryHandlePending(Reference.java:191)
        - locked <0x00000000f6706bf8> (a java.lang.ref.Reference$Lock)
        at java.lang.ref.Reference$ReferenceHandler.run(Reference.java:153)

"VM Thread" os_prio=0 tid=0x00007fcdfc073000 nid=0x74ea runnable

"GC task thread#0 (ParallelGC)" os_prio=0 tid=0x00007fcdfc01e800 nid=0x74e8 runnable

"GC task thread#1 (ParallelGC)" os_prio=0 tid=0x00007fcdfc020000 nid=0x74e9 runnable

"VM Periodic Task Thread" os_prio=0 tid=0x00007fcdfc0c7000 nid=0x74f1 waiting on condition

JNI global references: 5

 4. 对于3改成不用线程池再看一下

new Thread(new Runnable() {
            @Override
            public void run() {
                int i = 0;
                while ( true ) {
                    i++;
                    i--;
                }
            }
        }).start();

截取部分内容,看到区别

"Thread-0" #8 prio=5 os_prio=0 tid=0x00007fb8000df800 nid=0x757a runnable [0x00007fb7f02f1000]
   java.lang.Thread.State: RUNNABLE
        at ThreadTest$1.run(ThreadTest.java:9)
        at java.lang.Thread.run(Thread.java:748)

5. wait的情况

 1 import java.util.concurrent.ExecutorService;
 2 import java.util.concurrent.Executors;
 3 
 4 public class ThreadTest {
 5     public static void main (String[] args) {
 6         ExecutorService executorService = Executors.newFixedThreadPool(10);
 7         executorService.execute(new Runnable() {
 8             @Override
 9             public void run() {
10                 Object lock = new Object();
11                 synchronized ( lock ) {
12                     try {
13                         lock.wait();
14                     } catch (InterruptedException e) {
15                         e.printStackTrace();
16                     }
17                 }
18             }
19         });
20     }
21 }
"pool-1-thread-1" #8 prio=5 os_prio=0 tid=0x00007f88880ef800 nid=0x75c5 in Object.wait() [0x00007f887539d000]
   java.lang.Thread.State: WAITING (on object monitor)
        at java.lang.Object.wait(Native Method)
        - waiting on <0x00000000f67a8010> (a java.lang.Object)
        at java.lang.Object.wait(Object.java:502)
        at ThreadTest$1.run(ThreadTest.java:13)
        - locked <0x00000000f67a8010> (a java.lang.Object)
        at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149)
        at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
        at java.lang.Thread.run(Thread.java:748)

6. 带时间的wait(10000)

"pool-1-thread-1" #8 prio=5 os_prio=0 tid=0x00007f498c0f7800 nid=0x7607 in Object.wait() [0x00007f4977cfb000]
   java.lang.Thread.State: TIMED_WAITING (on object monitor)
        at java.lang.Object.wait(Native Method)
        - waiting on <0x00000000f67a8010> (a java.lang.Object)
        at ThreadTest$1.run(ThreadTest.java:13)
        - locked <0x00000000f67a8010> (a java.lang.Object)
        at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149)
        at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
        at java.lang.Thread.run(Thread.java:748)

7. lock

import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.locks.Lock;
import java.util.concurrent.locks.ReentrantLock;

public class ThreadTest {
    public static void main (String[] args) {
        ExecutorService executorService = Executors.newFixedThreadPool(10);
        executorService.execute(new Runnable() {
            @Override
            public void run() {
                Lock lock = new ReentrantLock();
                lock.lock();
            }
        });
    }
}
"pool-1-thread-1" #8 prio=5 os_prio=0 tid=0x00007fbe9c0ff800 nid=0x763f waiting on condition [0x00007fbe8cbfa000]
   java.lang.Thread.State: WAITING (parking)
        at sun.misc.Unsafe.park(Native Method)
        - parking to wait for  <0x00000000f675d9b0> (a java.util.concurrent.locks.AbstractQueuedSynchronizer$ConditionObject)
        at java.util.concurrent.locks.LockSupport.park(LockSupport.java:175)
        at java.util.concurrent.locks.AbstractQueuedSynchronizer$ConditionObject.await(AbstractQueuedSynchronizer.java:2039)
        at java.util.concurrent.LinkedBlockingQueue.take(LinkedBlockingQueue.java:442)
        at java.util.concurrent.ThreadPoolExecutor.getTask(ThreadPoolExecutor.java:1074)
        at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1134)
        at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
        at java.lang.Thread.run(Thread.java:748)

8.死锁测试

 1 import java.util.concurrent.ExecutorService;
 2 import java.util.concurrent.Executors;
 3 
 4 public class ThreadTest {
 5     public static void main (String[] args) {
 6         ExecutorService executorService = Executors.newFixedThreadPool(10);
 7         final Object A = new Object();
 8         final Object B = new Object();
 9 
10         final Runnable command1 = new Runnable() {
11             @Override
12             public void run() {
13                 synchronized ( A ) {
14                     try {
15                         Thread.sleep(10000);
16                     } catch (InterruptedException e) {
17                         e.printStackTrace();
18                     }
19                     synchronized ( B ) {
20 
21                     }
22                 }
23             }
24         };
25         final Runnable command2 = new Runnable() {
26             @Override
27             public void run() {
28                 synchronized ( B ) {
29                     try {
30                         Thread.sleep(10000);
31                     } catch (InterruptedException e) {
32                         e.printStackTrace();
33                     }
34                     synchronized ( A ) {
35 
36                     }
37                 }
38             }
39         };
40         executorService.execute(command1);
41         executorService.execute(command2);
42     }
43 }
2018-07-30 14:09:06
Full thread dump Java HotSpot(TM) 64-Bit Server VM (25.181-b13 mixed mode):

"Attach Listener" #11 daemon prio=9 os_prio=0 tid=0x00007f3ef8001000 nid=0x7728 waiting on condition [0x0000000000000000]
   java.lang.Thread.State: RUNNABLE

"DestroyJavaVM" #10 prio=5 os_prio=0 tid=0x00007f3f28009000 nid=0x7703 waiting on condition [0x0000000000000000]
   java.lang.Thread.State: RUNNABLE

"pool-1-thread-2" #9 prio=5 os_prio=0 tid=0x00007f3f280e9000 nid=0x770f waiting for monitor entry [0x00007f3f18af9000]
   java.lang.Thread.State: BLOCKED (on object monitor)
        at ThreadTest$2.run(ThreadTest.java:36)
        - waiting to lock <0x00000000f675de30> (a java.lang.Object)
        - locked <0x00000000f675de40> (a java.lang.Object)
        at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149)
        at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
        at java.lang.Thread.run(Thread.java:748)

"pool-1-thread-1" #8 prio=5 os_prio=0 tid=0x00007f3f280e7800 nid=0x770e waiting for monitor entry [0x00007f3f18bfa000]
   java.lang.Thread.State: BLOCKED (on object monitor)
        at ThreadTest$1.run(ThreadTest.java:21)
        - waiting to lock <0x00000000f675de40> (a java.lang.Object)
        - locked <0x00000000f675de30> (a java.lang.Object)
        at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149)
        at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
        at java.lang.Thread.run(Thread.java:748)

"Service Thread" #7 daemon prio=9 os_prio=0 tid=0x00007f3f280ba000 nid=0x770c runnable [0x0000000000000000]
   java.lang.Thread.State: RUNNABLE

"C1 CompilerThread1" #6 daemon prio=9 os_prio=0 tid=0x00007f3f280b7000 nid=0x770b waiting on condition [0x0000000000000000]
   java.lang.Thread.State: RUNNABLE

"C2 CompilerThread0" #5 daemon prio=9 os_prio=0 tid=0x00007f3f280b4000 nid=0x770a waiting on condition [0x0000000000000000]
   java.lang.Thread.State: RUNNABLE

"Signal Dispatcher" #4 daemon prio=9 os_prio=0 tid=0x00007f3f280b2800 nid=0x7709 runnable [0x0000000000000000]
   java.lang.Thread.State: RUNNABLE

"Finalizer" #3 daemon prio=8 os_prio=0 tid=0x00007f3f2807f800 nid=0x7708 in Object.wait() [0x00007f3f2c28e000]
   java.lang.Thread.State: WAITING (on object monitor)
        at java.lang.Object.wait(Native Method)
        - waiting on <0x00000000f6708ed0> (a java.lang.ref.ReferenceQueue$Lock)
        at java.lang.ref.ReferenceQueue.remove(ReferenceQueue.java:144)
        - locked <0x00000000f6708ed0> (a java.lang.ref.ReferenceQueue$Lock)
        at java.lang.ref.ReferenceQueue.remove(ReferenceQueue.java:165)
        at java.lang.ref.Finalizer$FinalizerThread.run(Finalizer.java:216)

"Reference Handler" #2 daemon prio=10 os_prio=0 tid=0x00007f3f2807d000 nid=0x7707 in Object.wait() [0x00007f3f2c38f000]
   java.lang.Thread.State: WAITING (on object monitor)
        at java.lang.Object.wait(Native Method)
        - waiting on <0x00000000f6706bf8> (a java.lang.ref.Reference$Lock)
        at java.lang.Object.wait(Object.java:502)
        at java.lang.ref.Reference.tryHandlePending(Reference.java:191)
        - locked <0x00000000f6706bf8> (a java.lang.ref.Reference$Lock)
        at java.lang.ref.Reference$ReferenceHandler.run(Reference.java:153)

"VM Thread" os_prio=0 tid=0x00007f3f28073000 nid=0x7706 runnable

"GC task thread#0 (ParallelGC)" os_prio=0 tid=0x00007f3f2801e800 nid=0x7704 runnable

"GC task thread#1 (ParallelGC)" os_prio=0 tid=0x00007f3f28020000 nid=0x7705 runnable

"VM Periodic Task Thread" os_prio=0 tid=0x00007f3f280bf000 nid=0x770d waiting on condition

JNI global references: 5


Found one Java-level deadlock:
=============================
"pool-1-thread-2":
  waiting to lock monitor 0x00007f3f040062c8 (object 0x00000000f675de30, a java.lang.Object),
  which is held by "pool-1-thread-1"
"pool-1-thread-1":
  waiting to lock monitor 0x00007f3f040038d8 (object 0x00000000f675de40, a java.lang.Object),
  which is held by "pool-1-thread-2"

Java stack information for the threads listed above:
===================================================
"pool-1-thread-2":
        at ThreadTest$2.run(ThreadTest.java:36)
        - waiting to lock <0x00000000f675de30> (a java.lang.Object)
        - locked <0x00000000f675de40> (a java.lang.Object)
        at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149)
        at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
        at java.lang.Thread.run(Thread.java:748)
"pool-1-thread-1":
        at ThreadTest$1.run(ThreadTest.java:21)
        - waiting to lock <0x00000000f675de40> (a java.lang.Object)
        - locked <0x00000000f675de30> (a java.lang.Object)
        at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149)
        at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
        at java.lang.Thread.run(Thread.java:748)

Found 1 deadlock.

9. 内存溢出 

参数简介

-Xmn:整个JVM内存大小=年轻代大小 + 年老代大小 + 持久代大小。持久代一般固定大小为64m,所以增大年轻代后,将会减小年老代大小。此值对系统性能影响较大,Sun官方推荐配置为整个堆的3/8。
-Xss128k:设置每个线程的堆栈大小,在相同物理内存下,减小这个值能生成更多的线程。但是操作系统对一个进程内的线程数还是有限制的,不能无限生成,经验值在3000~5000左右
-XX:NewRatio=4:设置年轻代(包括Eden和两个Survivor区)与年老代的比值(除去持久代)。设置为4,则年轻代与年老代所占比值为1:4,年轻代占整个堆栈的1/5
-XX:SurvivorRatio=4:设置年轻代中Eden区与Survivor区的大小比值。设置为4,则两个Survivor区与一个Eden区的比值为2:4,一个Survivor区占整个年轻代的1/6
-XX:MaxTenuringThreshold=0:设置垃圾最大年龄。如果设置为0的话,则年轻代对象不经过Survivor区,直接进入年老代。对于年老代比较多的应用,可以提高效率。
如果将此值设置为一个较大值,则年轻代对象会在Survivor区进行多次复制,这样可以增加对象再年轻代的存活时间,增加在年轻代即被回收的概率。

吞吐量优先的并行收集器

-XX:+UseParallelGC:选择垃圾收集器为并行收集器。此配置仅对年轻代有效
-XX:ParallelGCThreads=20:配置并行收集器的线程数,即:同时多少个线程一起进行垃圾回收。此值最好配置与处理器数目相等
-XX:+UseParallelOldGC:配置年老代垃圾收集方式为并行收集
-XX:MaxGCPauseMillis=100:设置每次年轻代垃圾回收的最长时间,如果无法满足此时间,JVM会自动调整年轻代大小,以满足此值
-XX:+UseAdaptiveSizePolicy:设置此选项后,并行收集器会自动选择年轻代区大小和相应的Survivor区比例,以达到目标系统规定的最低相应时间或者收集频率等,此值建议使用并行收集器时,一直打开

java -Xmx20m -Xms20m -Xmn10m  -XX:+UseParallelGC -XX:ParallelGCThreads=20 -XX:+UseParallelOldGC -XX:+PrintGCDetails -cp . ThreadTest

 1 import java.util.HashSet;
 2 import java.util.concurrent.ExecutorService;
 3 import java.util.concurrent.Executors;
 4 
 5 public class ThreadTest {
 6     public static void main (String[] args) {
 7         final HashSet hs = new HashSet();
 8         ExecutorService executorService = Executors.newFixedThreadPool(10);
 9         final Runnable command = new Runnable() {
10             @Override
11             public void run() {
12                 while ( true ) {
13                     try {
14                         Thread.sleep( 100 );
15                     } catch (InterruptedException e) {
16                         e.printStackTrace();
17                     }
18                     hs.add( new Object[1024 * 10]);
19                 }
20             }
21         };
22         executorService.execute(command);
23     }
24 }
[GC (Allocation Failure) [PSYoungGen: 8156K->1016K(9216K)] 8156K->7626K(19456K), 0.0071395 secs] [Times: user=0.00 sys=0.01, real=0.01 secs]
[Full GC (Ergonomics) [PSYoungGen: 1016K->0K(9216K)] [ParOldGen: 6610K->7556K(10240K)] 7626K->7556K(19456K), [Metaspace: 2637K->2637K(1056768K)], 0.0553513 secs] [Times: user=0.11 sys=0.00, real=0.05 secs]
[Full GC (Ergonomics) [PSYoungGen: 8156K->5562K(9216K)] [ParOldGen: 7556K->10111K(10240K)] 15712K->15674K(19456K), [Metaspace: 2643K->2643K(1056768K)], 0.0361699 secs] [Times: user=0.06 sys=0.00, real=0.03 secs]
[Full GC (Ergonomics) [PSYoungGen: 8158K->8125K(9216K)] [ParOldGen: 10111K->10111K(10240K)] 18270K->18237K(19456K), [Metaspace: 2643K->2643K(1056768K)], 0.0401159 secs] [Times: user=0.08 sys=0.00, real=0.04 secs]
[Full GC (Ergonomics) [PSYoungGen: 8192K->8165K(9216K)] [ParOldGen: 10111K->10111K(10240K)] 18303K->18277K(19456K), [Metaspace: 2643K->2643K(1056768K)], 0.0298122 secs] [Times: user=0.05 sys=0.00, real=0.03 secs]
[Full GC (Ergonomics) [PSYoungGen: 8192K->8165K(9216K)] [ParOldGen: 10231K->10231K(10240K)] 18423K->18397K(19456K), [Metaspace: 2643K->2643K(1056768K)], 0.0359396 secs] [Times: user=0.07 sys=0.01, real=0.04 secs]
[Full GC (Allocation Failure) [PSYoungGen: 8165K->8165K(9216K)] [ParOldGen: 10231K->10231K(10240K)] 18397K->18397K(19456K), [Metaspace: 2643K->2643K(1056768K)], 0.0313513 secs] [Times: user=0.06 sys=0.00, real=0.03 secs]
Exception in thread "pool-1-thread-1" [Full GC (Ergonomics) [PSYoungGen: 8192K->0K(9216K)] [ParOldGen: 10234K->255K(10240K)] 18426K->255K(19456K), [Metaspace: 2667K->2667K(1056768K)], 0.0116908 secs] [Times: user=0.02 sys=0.00, real=0.01 secs]
java.lang.OutOfMemoryError: Java heap space
        at ThreadTest$1.run(ThreadTest.java:18)
        at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149)
        at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
        at java.lang.Thread.run(Thread.java:748)
Heap
 PSYoungGen      total 9216K, used 443K [0x00000000ff600000, 0x0000000100000000, 0x0000000100000000)
  eden space 8192K, 5% used [0x00000000ff600000,0x00000000ff66ef10,0x00000000ffe00000)
  from space 1024K, 0% used [0x00000000ffe00000,0x00000000ffe00000,0x00000000fff00000)
  to   space 1024K, 0% used [0x00000000fff00000,0x00000000fff00000,0x0000000100000000)
 ParOldGen       total 10240K, used 255K [0x00000000fec00000, 0x00000000ff600000, 0x00000000ff600000)
  object space 10240K, 2% used [0x00000000fec00000,0x00000000fec3feb8,0x00000000ff600000)
 Metaspace       used 2683K, capacity 4486K, committed 4864K, reserved 1056768K
  class space    used 292K, capacity 386K, committed 512K, reserved 1048576K

jinfo 31367

VM Flags:
Non-default VM flags: -XX:CICompilerCount=2 -XX:InitialHeapSize=20971520 -XX:MaxHeapSize=20971520 -XX:MaxNewSize=10485760 -XX:MinHeapDeltaBytes=524288 -XX:NewSize=10485760 -XX:OldSize=10485760 -XX:ParallelGCThreads=20 -XX:+PrintGCDetails -XX:+UseCompressedClassPointers -XX:+UseCompressedOops -XX:+UseParallelGC -XX:+UseParallelOldGC
Command line:  -Xmx20m -Xms20m -Xmn10m -XX:+UseParallelGC -XX:ParallelGCThreads=20 -XX:+UseParallelOldGC -XX:+PrintGCDetails

 jmap -histo 31367

 num     #instances         #bytes  class name
----------------------------------------------
   1:           645        4861968  [Ljava.lang.Object;
   2:           443         493928  [I
   3:          1677         152136  [C

响应时间优先的收集器配置

-XX:+UseConcMarkSweepGC:设置年老代为并发收集
-XX:+UseParNewGC:设置年轻代为并行收集
-XX:CMSFullGCsBeforeCompaction:由于并发收集器不对内存空间进行压缩、整理,所以运行一段时间以后会产生“碎片”,使得运行效率降低。此值设置运行多少次GC以后对内存空间进行压缩、整理。
-XX:+UseCMSCompactAtFullCollection:打开对年老代的压缩。可能会影响性能,但是可以消除碎片

java -Xmx20m -Xms20m -Xmn10m -XX:ParallelGCThreads=20 -XX:+UseConcMarkSweepGC -XX:+UseParNewGC -XX:+PrintGCDetails -cp . ThreadTest

[GC (Allocation Failure) [ParNew: 8156K->1023K(9216K), 0.0515080 secs] 8156K->7627K(19456K), 0.0515731 secs] [Times: user=0.10 sys=0.00, real=0.05 secs]
[GC (CMS Initial Mark) [1 CMS-initial-mark: 6603K(10240K)] 7667K(19456K), 0.0015729 secs] [Times: user=0.00 sys=0.00, real=0.01 secs]
[CMS-concurrent-mark-start]
[CMS-concurrent-mark: 0.001/0.001 secs] [Times: user=0.00 sys=0.00, real=0.00 secs]
[CMS-concurrent-preclean-start]
[CMS-concurrent-preclean: 0.000/0.000 secs] [Times: user=0.00 sys=0.00, real=0.00 secs]
[GC (CMS Final Remark) [YG occupancy: 1064 K (9216 K)][Rescan (parallel) , 0.0120069 secs][weak refs processing, 0.0000126 secs][class unloading, 0.0002688 secs][scrub symbol table, 0.0004252 secs][scrub string table, 0.0001109 secs][1 CMS-remark: 6603K(10240K)] 7667K(19456K), 0.0129012 secs] [Times: user=0.02 sys=0.00, real=0.01 secs]
[CMS-concurrent-sweep-start]
[CMS-concurrent-sweep: 0.000/0.000 secs] [Times: user=0.01 sys=0.00, real=0.00 secs]
[CMS-concurrent-reset-start]
[CMS-concurrent-reset: 0.000/0.000 secs] [Times: user=0.00 sys=0.00, real=0.00 secs]
....
[CMS-concurrent-mark-start]
[CMS-concurrent-mark: 0.002/0.002 secs] [Times: user=0.00 sys=0.00, real=0.00 secs]
[CMS-concurrent-preclean-start]
[CMS-concurrent-preclean: 0.000/0.000 secs] [Times: user=0.00 sys=0.00, real=0.00 secs]
[CMS-concurrent-abortable-preclean-start]
[CMS-concurrent-abortable-preclean: 0.000/0.000 secs] [Times: user=0.00 sys=0.00, real=0.00 secs]
[GC (CMS Final Remark) [YG occupancy: 9197 K (9216 K)][Rescan (parallel) , 0.0141205 secs][weak refs processing, 0.0000115 secs][class unloading, 0.0003192 secs][scrub symbol table, 0.0004989 secs][scrub string table, 0.0001190 secs][1 CMS-remark: 10214K(10240K)] 19412K(19456K), 0.0151344 secs] [Times: user=0.03 sys=0.00, real=0.02 secs]
[CMS-concurrent-sweep-start]
[CMS-concurrent-sweep: 0.000/0.000 secs] [Times: user=0.00 sys=0.00, real=0.00 secs]
[CMS-concurrent-reset-start]
[CMS-concurrent-reset: 0.000/0.000 secs] [Times: user=0.00 sys=0.00, real=0.00 secs]
^CHeap
 par new generation   total 9216K, used 9199K [0x00000000fec00000, 0x00000000ff600000, 0x00000000ff600000)
  eden space 8192K, 100% used [0x00000000fec00000, 0x00000000ff400000, 0x00000000ff400000)
  from space 1024K,  98% used [0x00000000ff500000, 0x00000000ff5fbcc0, 0x00000000ff600000)
  to   space 1024K,   0% used [0x00000000ff400000, 0x00000000ff400000, 0x00000000ff500000)
 concurrent mark-sweep generation total 10240K, used 10214K [0x00000000ff600000, 0x0000000100000000, 0x0000000100000000)
 Metaspace       used 2685K, capacity 4486K, committed 4864K, reserved 1056768K
  class space    used 292K, capacity 386K, committed 512K, reserved 1048576K

 10. 线程池相关

 1 package io.netty.example.myTest;
 2 
 3 import java.util.concurrent.*;
 4 
 5 public class ThreadTest {
 6     public static void main (String[] args) {
 7         // 先2,然后queue,满了之后运行线程增加到max
 8         //针对本例子,先创建2个线程,t1,t2进入线程池之后直接执行,t3加入阻塞队列,队列满,t4到来线程池扩张线程到max运行t4,t5到来无法处理,进入到reject
 9         ExecutorService executorService = new ThreadPoolExecutor(2, 3,
10                 0L, TimeUnit.MILLISECONDS,
11                 new ArrayBlockingQueue<Runnable>(1), Executors.defaultThreadFactory(), new ThreadPoolExecutor.AbortPolicy());
12         Thread t1 = new Thread(new Runnable() {
13                     @Override
14                     public void run() {
15                         int i = 0;
16                         while (true) {
17                             i++;
18                             i--;
19                         }
20                     }
21                 }, "1-test");
22         Thread t2 = new Thread(new Runnable() {
23             @Override
24             public void run() {
25                 int i = 0;
26                 while (true) {
27                     i++;
28                     i--;
29                 }
30             }
31         }, "2-test");
32         Thread t3 = new Thread(new Runnable() {
33             @Override
34             public void run() {
35                 int i = 0;
36                 while (true) {
37                     i++;
38                     i--;
39                 }
40             }
41         }, "3-test");
42         Thread t4 = new Thread(new Runnable() {
43             @Override
44             public void run() {
45                 int i = 0;
46                 while (true) {
47                     i++;
48                     i--;
49                 }
50             }
51         }, "4-test");
52         Thread t5 = new Thread(new Runnable() {
53             @Override
54             public void run() {
55                 int i = 0;
56                 while (true) {
57                     i++;
58                     i--;
59                 }
60             }
61         }, "5-test");
62         executorService.execute(t1);
63         executorService.execute(t2);
64         executorService.execute(t3);
65         executorService.execute(t4);
66         executorService.execute(t5);
67     }
68 }

由于先创建2个线程,t1,t2进入线程池之后直接执行,t3加入阻塞队列,队列满,t4到来线程池扩张线程到max运行t4,t5到来无法处理,进入到reject,所以运行结果如下

Exception in thread "main" java.util.concurrent.RejectedExecutionException: Task Thread[5-test,5,main] rejected from java.util.concurrent.ThreadPoolExecutor@27716f4[Running, pool size = 3, active threads = 3, queued tasks = 1, completed tasks = 0]
    at java.util.concurrent.ThreadPoolExecutor$AbortPolicy.rejectedExecution(ThreadPoolExecutor.java:2063)
    at java.util.concurrent.ThreadPoolExecutor.reject(ThreadPoolExecutor.java:830)
    at java.util.concurrent.ThreadPoolExecutor.execute(ThreadPoolExecutor.java:1379)
    at io.netty.example.myTest.ThreadTest.main(ThreadTest.java:66)

如果new ArrayBlockingQueue<Runnable>(1) 改为 new LinkedBlockingQueue<Runnable>(), 则缓存队列无界,不会报上面的错

11. CPU饱和

同样用上面的例子,改为无界队列

前面两个线程T1/T2在运行
"pool-1-thread-2" #14 prio=5 os_prio=0 tid=0x00007f43c40e9800 nid=0x7c4a runnable [0x00007f43aed13000]
   java.lang.Thread.State: RUNNABLE
        at ThreadTest$2.run(ThreadTest.java:24)
        at java.lang.Thread.run(Thread.java:748)
        at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149)
        at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
        at java.lang.Thread.run(Thread.java:748)

"pool-1-thread-1" #13 prio=5 os_prio=0 tid=0x00007f43c40e7800 nid=0x7c49 runnable [0x00007f43aee14000]
   java.lang.Thread.State: RUNNABLE
        at ThreadTest$1.run(ThreadTest.java:14)
        at java.lang.Thread.run(Thread.java:748)
        at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149)
        at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
        at java.lang.Thread.run(Thread.java:748)

 [root@izm5e8p93wtcdi53pzqhi7z test]# cat /proc/cpuinfo 可以看到在两个CPU的情况下,%CPU最高达到200%

 top -Hp 31805

 

posted on 2018-07-30 15:25  it_worker365  阅读(259)  评论(0编辑  收藏  举报