语言基础 / Java40 分钟 读完 (大约 5948 个字)

Ubuntu编译glibc库来验证Synchronized锁优化效果

0.前言


当然你可以说通过JOL查看对象的头信息，当然那个也是一种方法，但那个只能说明是这种状态，没有过程，本次主要结合来验证，Synchronized 关键字锁的状态：无锁、偏向锁、轻量级锁、重量级锁

基于Ubuntu16测试成功。18测试失败，centos没有测试




主要是在Java调用系统函数的时候，打印log。但是在Java里面打印线程ID是JVM层面的。需要自己实现一个native方法，在java层面调用。最后对比对应的PID 和TID，发现查看当前线程调用了几次系统锁
Java 的重量级级锁都是通过glibc库的pthread_mutex_lock函数实现的，是在和操作系统级别的锁。

glibc库


glibc是linux系统中最底层的api，几乎其它任何运行库都会依赖于glibc。glibc除了封装linux操作系统所提供的系统服务外，它本身也提供了许多其它一些必要功能服务的实现。

  • 操作系统底层库

int pthread_mutex_lock(pthread_mutex_t *mutex);


pthread_mutex_lock()返回时，该互斥锁已被锁定。线程调用该函数让互斥锁上锁，如果该互斥锁已被另一个线程锁定和拥有，则调用该线程将阻塞，直到该互斥锁变为可用为止。 对于 Solaris线程，请参见mutex_lock 语法

  • 会阻塞


我们可以从JVM 源码中看到调用

ThreadCritical::ThreadCritical

1
2
3
4
5
6
7
8
9
10
ThreadCritical::ThreadCritical() {
  pthread_t self = pthread_self();
  if (self != tc_owner) {
    int ret = pthread_mutex_lock(&tc_mutex);
    guarantee(ret == 0, "fatal error with pthread_mutex_lock()");
    assert(tc_count == 0, "Lock acquired with illegal reentry count.");
    tc_owner = self;
  }
  tc_count++;
}


这个是底层系统库，我们是看不到源码的，只能自己下载。可以在glibc/nptl/phread_mutex_lock.c里看到实现。
我尝试就是在这里函数里加上自己的log

1
2
3
4
5
int __pthread_mutex_lock (pthread_mutex_t *mutex)
{ 
  //打印log
  fprintf(stdout,"pthread_mutex_lock log  PID = %d TID = %lu  mutex = %p \n",getpid(),pthread_self(),&mutex); 
  ---

1. 查看自己的glibc版本

1
2
3
4
5
root@189415df5c51:/lib/x86_64-linux-gnu# pwd
/lib/x86_64-linux-gnu
root@189415df5c51:/lib/x86_64-linux-gnu# ls -l libc.so.6
lrwxrwxrwx 1 root root 12 Feb  5  2019 libc.so.6 -> libc-2.23.so
root@189415df5c51:/lib/x86_64-linux-gnu#

2.最好下载同一个版本，编译glibc版本


https://ftp.gnu.org/gnu/glibc/?C=M;O=A
目录可以自己变化，但是glibc不让在源码目录下面编译 会报 Makeconfig:42: *** missing separator. Stop




若有必要，可以参考 Linux源码包的一般安装步

1
2
3
4
5
mkdir build
cd build
./../configure  --prefix = usr/local/glibc 
make
make install

3.修改替换 编译


vim pthread_mutex_lock.c 添加log

1
fprintf(stdout,"pthread_mutex_lock log  PID = %d TID = %lu  mutex = %p \n",getpid(),pthread_self(),&mutex);

4.运行时替换关键库

  • 这里需要注意，搞错了，就不能的话，所有命令都可能用不了了


自己主要修改的是pthread库，所以替换系统的pthread库，find一下

  • 1.查看 /etc/ld.conf.d/x86-gnu*.conf 下的目录
  • 2.因为要替换几个关键文件，直接手动替换会出错，系统库是在动态加载的。copy 一个临时目录，加上了n后缀，做区分。去替换临时目录里面的文件
  • 3.例如我的
1
2
3
4
5
cp /usr/local/glibc23/lib/libpthread.so /usr/lib/x86_64-linux-gnu-n/libpthread.so
cp /usr/local/glibc23/lib/libpthread_nonshared.a /usr/lib/x86_64-linux-gnu-n/libpthread_nonshared.a
cp /usr/local/glibc23/lib/libpthread.a /usr/lib/x86_64-linux-gnu-n/libpthread.a
cp /usr/local/glibc23/lib/libpthread-2.23.so  /lib/x86_64-linux-gnu-n/libpthread-2.23.so
cp /usr/local/glibc23/lib/libpthread.so.0 /lib/x86_64-linux-gnu-n/libpthread.so.0
  • 4.修改 /etc/ld.conf.d/x86-gnu*.conf 里面的链接库路径指向临时目录，不用了可以改回
  • 5.执行ldconfig，生效
  • 6.自己配置java环境
  • 基本任命令都会触发这行log
1
2
3
root@189415df5c51:/etc/ld.so.conf.d# ls
pthread_mutex_lock log  PID = 62030 TID = 140453473769472 mutex=0x7fbddf6a1948
libc.conf  x86_64-linux-gnu.conf

5.编写Java验证


接下来，就是正常jni流程了

JniTool.java

1
2
3
4
5
6
7
8
package jnitool;

public class JniTool {
    static {
        System.loadLibrary("jnitools");
    }
    public native void getThreadID();
}


这里jnitool必须在 java.library.path这一jvm变量所指向的路径中，
可以通过如下方法获得该变量System.getProperty(“java.library.path”);

生成.h文件，javah -jni jnitool.JniTool


打印java线程的pid和tid，jvm层面

1
2
3
4
5
6
7
8
9
10
#include "jnitool_JniTool.h"
#include <stdio.h>
#include <pthread.h>
#include <unistd.h>

JNIEXPORT void JNICALL Java_jnitool_JniTool_getThreadID
  (JNIEnv * env, jobject obj){
        fprintf(stdout,"java_lock log  PID = %d TID = %lu \n",getpid(),pthread_self());
        fflush(stdout);//刷新，防止错位打印
}

使用make编译

1
2
3
4
5
6
vim makefile

libjnitools.so:
	gcc -lpthread -fPIC -shared -o libjnitools.so  -I /root/jdk1.8.0_221/include/ -I /root/jdk1.8.0_221/include/linux/ ./jnitools.c
  
make

6. 观察不同的锁

  • 主要是对比不同的锁情况下，对操作系统系统锁的调用情况，观察优化效果
  • 当然JVM对锁的优化，是调用系统锁的次数越少越好
  • 听过系统锁的log，直观对比调用pthread_mutex_lock次数
  • 奇怪的是我在docker里面，修改glibc库后，加上jol打印头信息就会卡，所以先验证是什么锁的情况下，再打的log

6.1 无锁

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
public class SyncTest {
    //测试锁
    final Object lock = new Object();
    //获取pthread  tid
    JniTool jniTool = new JniTool();

    public static void main(String[] args) throws InterruptedException {
        //不打开，默认就是无所的状态
        //Thread.sleep(5000);
        SyncTest test = new SyncTest();
        System.out.println("---------------------------start--------------------");
        test.start();
    }

    public void start() throws InterruptedException {
        Runnable runnable = new Runnable() {
            @Override
            public void run() {
                int count = 0;
                System.out.println(Thread.currentThread().getName() + " start");
                while (true) {
                    if (count < 50) {
                        count++;
                    } else {
                        return;
                    }
                    try {
                        lock();
                    } catch (InterruptedException e) {
                        e.printStackTrace();
                    }
                }
            }
        };
        new Thread(runnable).start();
    }
    public void lock() throws InterruptedException {
        synchronized (lock) {
            jniTool.getThreadID();
        }
    }
}

out.log

  • 通过log可以看到50次调用,通过搜索tid查看

  • 刚开始和结束调用了系统锁，中间是没有调用系统锁

    1
    2
    3
    4
    5
    6
    7
    8
    9
    10
    11
    12
    13
    14
    15
    16
    17
    18
    19
    20
    21
    22
    23
    24
    25
    26
    27
    28
    29
    30
    31
    32
    33
    34
    35
    36
    37
    38
    39
    40
    41
    42
    43
    44
    45
    46
    47
    48
    49
    50
    51
    52
    53
    54
    55
    56
    57
    58
    3545: pthread_mutex_lock log  PID = 399 TID = 140058569967360 mutex=0x7f61e800b728 
      3546: pthread_mutex_lock log  PID = 399 TID = 140058569967360 mutex=0x7f61e8100b28 
      3549: pthread_mutex_lock log  PID = 399 TID = 140058569967360 mutex=0x7f61e8100b28 
      3555: pthread_mutex_lock log  PID = 399 TID = 140058569967360 mutex=0x7f61e80b9228 
      3562: pthread_mutex_lock log  PID = 399 TID = 140058569967360 mutex=0x7f61f778b8a0 
      3563: pthread_mutex_lock log  PID = 399 TID = 140058569967360 mutex=0x7f61f83d3948 
      3564: java_lock log-----------PID = 399 TID = 140058569967360 
      3575: java_lock log-----------PID = 399 TID = 140058569967360 
      3576: java_lock log-----------PID = 399 TID = 140058569967360 
      3577: java_lock log-----------PID = 399 TID = 140058569967360 
      3578: java_lock log-----------PID = 399 TID = 140058569967360 
      3579: java_lock log-----------PID = 399 TID = 140058569967360 
      3580: java_lock log-----------PID = 399 TID = 140058569967360 
      3581: java_lock log-----------PID = 399 TID = 140058569967360 
      3582: java_lock log-----------PID = 399 TID = 140058569967360 
      3583: java_lock log-----------PID = 399 TID = 140058569967360 
      3584: java_lock log-----------PID = 399 TID = 140058569967360 
      3585: java_lock log-----------PID = 399 TID = 140058569967360 
      3586: java_lock log-----------PID = 399 TID = 140058569967360 
      3587: java_lock log-----------PID = 399 TID = 140058569967360 
      3588: java_lock log-----------PID = 399 TID = 140058569967360 
      3590: java_lock log-----------PID = 399 TID = 140058569967360 
      3591: java_lock log-----------PID = 399 TID = 140058569967360 
      3592: java_lock log-----------PID = 399 TID = 140058569967360 
      3593: java_lock log-----------PID = 399 TID = 140058569967360 
      3594: java_lock log-----------PID = 399 TID = 140058569967360 
      3595: java_lock log-----------PID = 399 TID = 140058569967360 
      3596: java_lock log-----------PID = 399 TID = 140058569967360 
      3597: java_lock log-----------PID = 399 TID = 140058569967360 
      3598: java_lock log-----------PID = 399 TID = 140058569967360 
      3599: java_lock log-----------PID = 399 TID = 140058569967360 
      3600: java_lock log-----------PID = 399 TID = 140058569967360 
      3601: java_lock log-----------PID = 399 TID = 140058569967360 
      3602: java_lock log-----------PID = 399 TID = 140058569967360 
      3603: java_lock log-----------PID = 399 TID = 140058569967360 
      3604: java_lock log-----------PID = 399 TID = 140058569967360 
      3605: java_lock log-----------PID = 399 TID = 140058569967360 
      3606: java_lock log-----------PID = 399 TID = 140058569967360 
      3607: java_lock log-----------PID = 399 TID = 140058569967360 
      3608: java_lock log-----------PID = 399 TID = 140058569967360 
      3609: java_lock log-----------PID = 399 TID = 140058569967360 
      3610: java_lock log-----------PID = 399 TID = 140058569967360 
      3611: java_lock log-----------PID = 399 TID = 140058569967360 
      3612: java_lock log-----------PID = 399 TID = 140058569967360 
      3613: java_lock log-----------PID = 399 TID = 140058569967360 
      3614: java_lock log-----------PID = 399 TID = 140058569967360 
      3615: java_lock log-----------PID = 399 TID = 140058569967360 
      3616: java_lock log-----------PID = 399 TID = 140058569967360 
      3617: java_lock log-----------PID = 399 TID = 140058569967360 
      3618: java_lock log-----------PID = 399 TID = 140058569967360 
      3619: java_lock log-----------PID = 399 TID = 140058569967360 
      3620: java_lock log-----------PID = 399 TID = 140058569967360 
      3621: java_lock log-----------PID = 399 TID = 140058569967360 
      3622: java_lock log-----------PID = 399 TID = 140058569967360 
      3623: java_lock log-----------PID = 399 TID = 140058569967360 
      3624: pthread_mutex_lock log  PID = 399 TID = 140058569967360 mutex=0x7f61e800b528 
      3625: pthread_mutex_lock log  PID = 399 TID = 140058569967360 mutex=0x7f61f77a32c0 
      3626: pthread_mutex_lock log  PID = 399 TID = 140058569967360 mutex=0x7f61f77a32c0

    6.2 偏向锁

  • 偏向锁是默认延时加载的

  • 我们可以加JVM参数或sleep

  • 通过上面的代码，加上 Thread.sleep(5000);确保偏向锁打开


    out.log

  • 查看输出, 效果如上

    1
    2
    3
    4
    5
    6
    7
    8
    9
    10
    11
    12
    13
    14
    15
    16
    17
    18
    19
    20
    21
    22
    23
    24
    25
    26
    27
    28
    29
    30
    31
    32
    33
    34
    35
    36
    37
    38
    39
    40
    41
    42
    43
    44
    45
    46
    47
    48
    49
    50
    51
    52
    53
    54
    55
    56
    57
    58
    59
    60
    61
    62
    3742: pthread_mutex_lock log  PID = 431 TID = 139799890413312 mutex=0x7f25c800b728 
      3743: pthread_mutex_lock log  PID = 431 TID = 139799890413312 mutex=0x7f25c80e9128 
      3750: pthread_mutex_lock log  PID = 431 TID = 139799890413312 mutex=0x7f25c80e9128 
      3752: pthread_mutex_lock log  PID = 431 TID = 139799890413312 mutex=0x7f25c80b9228 
      3763: pthread_mutex_lock log  PID = 431 TID = 139799890413312 mutex=0x7f25cffe18a0 
      3764: pthread_mutex_lock log  PID = 431 TID = 139799890413312 mutex=0x7f25d4c8b948 
      3765: java_lock log-----------PID = 431 TID = 139799890413312 
      3772: java_lock log-----------PID = 431 TID = 139799890413312 
      3773: java_lock log-----------PID = 431 TID = 139799890413312 
      3774: java_lock log-----------PID = 431 TID = 139799890413312 
      3775: java_lock log-----------PID = 431 TID = 139799890413312 
      3776: java_lock log-----------PID = 431 TID = 139799890413312 
      3777: java_lock log-----------PID = 431 TID = 139799890413312 
      3778: java_lock log-----------PID = 431 TID = 139799890413312 
      3779: java_lock log-----------PID = 431 TID = 139799890413312 
      3780: java_lock log-----------PID = 431 TID = 139799890413312 
      3781: java_lock log-----------PID = 431 TID = 139799890413312 
      3782: java_lock log-----------PID = 431 TID = 139799890413312 
      3783: java_lock log-----------PID = 431 TID = 139799890413312 
      3785: java_lock log-----------PID = 431 TID = 139799890413312 
      3787: java_lock log-----------PID = 431 TID = 139799890413312 
      3788: java_lock log-----------PID = 431 TID = 139799890413312 
      3789: java_lock log-----------PID = 431 TID = 139799890413312 
      3790: java_lock log-----------PID = 431 TID = 139799890413312 
      3791: java_lock log-----------PID = 431 TID = 139799890413312 
      3792: java_lock log-----------PID = 431 TID = 139799890413312 
      3793: java_lock log-----------PID = 431 TID = 139799890413312 
      3794: java_lock log-----------PID = 431 TID = 139799890413312 
      3795: java_lock log-----------PID = 431 TID = 139799890413312 
      3796: java_lock log-----------PID = 431 TID = 139799890413312 
      3797: java_lock log-----------PID = 431 TID = 139799890413312 
      3798: java_lock log-----------PID = 431 TID = 139799890413312 
      3799: java_lock log-----------PID = 431 TID = 139799890413312 
      3800: java_lock log-----------PID = 431 TID = 139799890413312 
      3801: java_lock log-----------PID = 431 TID = 139799890413312 
      3802: java_lock log-----------PID = 431 TID = 139799890413312 
      3803: java_lock log-----------PID = 431 TID = 139799890413312 
      3804: java_lock log-----------PID = 431 TID = 139799890413312 
      3805: java_lock log-----------PID = 431 TID = 139799890413312 
      3806: java_lock log-----------PID = 431 TID = 139799890413312 
      3807: java_lock log-----------PID = 431 TID = 139799890413312 
      3808: java_lock log-----------PID = 431 TID = 139799890413312 
      3809: java_lock log-----------PID = 431 TID = 139799890413312 
      3810: java_lock log-----------PID = 431 TID = 139799890413312 
      3811: java_lock log-----------PID = 431 TID = 139799890413312 
      3812: java_lock log-----------PID = 431 TID = 139799890413312 
      3813: java_lock log-----------PID = 431 TID = 139799890413312 
      3814: java_lock log-----------PID = 431 TID = 139799890413312 
      3815: java_lock log-----------PID = 431 TID = 139799890413312 
      3816: java_lock log-----------PID = 431 TID = 139799890413312 
      3817: java_lock log-----------PID = 431 TID = 139799890413312 
      3818: java_lock log-----------PID = 431 TID = 139799890413312 
      3819: java_lock log-----------PID = 431 TID = 139799890413312 
      3820: java_lock log-----------PID = 431 TID = 139799890413312 
      3821: java_lock log-----------PID = 431 TID = 139799890413312 
      3822: java_lock log-----------PID = 431 TID = 139799890413312 
      3823: pthread_mutex_lock log  PID = 431 TID = 139799890413312 mutex=0x7f25c8079528 
      3824: pthread_mutex_lock log  PID = 431 TID = 139799890413312 mutex=0x7f25c80e9128 
      3828: pthread_mutex_lock log  PID = 431 TID = 139799890413312 mutex=0x7f25c80e9128 
      3829: pthread_mutex_lock log  PID = 431 TID = 139799890413312 mutex=0x7f25c800b528 
      3830: pthread_mutex_lock log  PID = 431 TID = 139799890413312 mutex=0x7f25cfff92c0 
      3831: pthread_mutex_lock log  PID = 431 TID = 139799890413312 mutex=0x7f25cfff92c0

6.3 轻量级锁

  • 我们偏向锁，升级到轻量级锁
    1
    2
    3
    4
    5
    6
    7
    8
    9
    10
    11
    12
    13
    14
    15
    16
    17
    18
    19
    20
    21
    22
    23
    24
    25
    26
    27
    28
    29
    30
    31
    32
    33
    34
    35
    36
    37
    38
    39
    40
    41
    42
    43
    44
    45
    46
    47
    48
    49
    50
    51
    52
    53
    54
    55
    56
    public class SyncTest {
        //测试锁
        final Object lock = new Object();
        //获取pthread  tid
        JniTool jniTool = new JniTool();

        public static void main(String[] args) throws InterruptedException {
            //打开就是默认的偏向锁，默认是可偏向状态，但是不偏向任何一个线程
            //不打开，默认就是无所的状态
            Thread.sleep(5000);
            SyncTest test = new SyncTest();
            // test.parseHeaderInfo((ClassLayout.parseInstance(test.lock).toPrintable()));
            System.out.println("---------------------------start--------------------");
            test.start();
        }

        public void start() throws InterruptedException {
            Runnable runnable = new Runnable() {
                @Override
                public void run() {
                    int count = 0;
                    System.out.println(Thread.currentThread().getName() + " start");
                    while (true) {
                        if (count < 50) {
                            count++;
                        } else {
                        //若线程没有结束，但是线程1放锁了，升级为轻量级锁
                           try {
                               Thread.sleep(100000);
                           } catch (InterruptedException e) {
                               e.printStackTrace();
                           }
                            return;
                        }
                        try {
                            lock();
                            // parseHeaderInfo(ClassLayout.parseInstance(lock).toPrintable());
                        } catch (InterruptedException e) {
                            e.printStackTrace();
                        }
                    }
                }
            };
            new Thread(runnable).start();
            //加上，保证线程1结束，若果线程1已经结束，则还是偏向锁
            //若线程没有结束，但是线程1放锁了，升级为轻量级锁
            Thread.sleep(2000);
            //不加,则会升级为重量级锁
           new Thread(runnable).start();
        }
        public void lock() throws InterruptedException {
            synchronized (lock) {
                jniTool.getThreadID();
            }
        }
    }
  • out.log
  • 线程1的时候偏向
  • 线程2的时候，升级到轻量级锁
    1
    2
    3
    4
    5
    6
    7
    8
    9
    10
    11
    12
    13
    14
    15
    16
    17
    18
    19
    20
    21
    22
    23
    24
    25
    26
    27
    28
    29
    30
    31
    32
    33
    34
    35
    36
    37
    38
    39
    40
    41
    42
    43
    44
    45
    46
    47
    48
    49
    50
    51
    52
    53
    54
    55
    56
    57
    58
    59
    60
    61
    62
    63
    64
    65
    66
    67
    68
    69
    70
    71
    72
    73
    74
    75
    76
    77
    78
    79
    80
    81
    82
    83
    84
    85
    86
    87
    88
    89
    90
    91
    92
    93
    94
    95
    96
    97
    98
    99
    100
    101
    102
    103
    104
    105
    106
    107
    108
    109
    110
    111
    112
    113
    114
    3763: pthread_mutex_lock log  PID = 498 TID = 139928822331136 mutex=0x7f43cc00b728 
      3764: pthread_mutex_lock log  PID = 498 TID = 139928822331136 mutex=0x7f43cc108d28 
      3768: pthread_mutex_lock log  PID = 498 TID = 139928822331136 mutex=0x7f43cc108d28 
      3769: pthread_mutex_lock log  PID = 498 TID = 139928822331136 mutex=0x7f43cc0bba28 
      3774: pthread_mutex_lock log  PID = 498 TID = 139928822331136 mutex=0x7f43d3fe18a0 
      3775: pthread_mutex_lock log  PID = 498 TID = 139928822331136 mutex=0x7f43d9bea948 
      3777: java_lock log-----------PID = 498 TID = 139928822331136 
      3789: java_lock log-----------PID = 498 TID = 139928822331136 
      3790: java_lock log-----------PID = 498 TID = 139928822331136 
      3791: java_lock log-----------PID = 498 TID = 139928822331136 
      3792: java_lock log-----------PID = 498 TID = 139928822331136 
      3793: java_lock log-----------PID = 498 TID = 139928822331136 
      3794: java_lock log-----------PID = 498 TID = 139928822331136 
      3795: java_lock log-----------PID = 498 TID = 139928822331136 
      3796: java_lock log-----------PID = 498 TID = 139928822331136 
      3797: java_lock log-----------PID = 498 TID = 139928822331136 
      3798: java_lock log-----------PID = 498 TID = 139928822331136 
      3799: java_lock log-----------PID = 498 TID = 139928822331136 
      3800: java_lock log-----------PID = 498 TID = 139928822331136 
      3801: java_lock log-----------PID = 498 TID = 139928822331136 
      3802: java_lock log-----------PID = 498 TID = 139928822331136 
      3803: java_lock log-----------PID = 498 TID = 139928822331136 
      3804: java_lock log-----------PID = 498 TID = 139928822331136 
      3805: java_lock log-----------PID = 498 TID = 139928822331136 
      3806: java_lock log-----------PID = 498 TID = 139928822331136 
      3807: java_lock log-----------PID = 498 TID = 139928822331136 
      3808: java_lock log-----------PID = 498 TID = 139928822331136 
      3809: java_lock log-----------PID = 498 TID = 139928822331136 
      3810: java_lock log-----------PID = 498 TID = 139928822331136 
      3811: java_lock log-----------PID = 498 TID = 139928822331136 
      3812: java_lock log-----------PID = 498 TID = 139928822331136 
      3813: java_lock log-----------PID = 498 TID = 139928822331136 
      3814: java_lock log-----------PID = 498 TID = 139928822331136 
      3815: java_lock log-----------PID = 498 TID = 139928822331136 
      3816: java_lock log-----------PID = 498 TID = 139928822331136 
      3817: java_lock log-----------PID = 498 TID = 139928822331136 
      3818: java_lock log-----------PID = 498 TID = 139928822331136 
      3819: java_lock log-----------PID = 498 TID = 139928822331136 
      3820: java_lock log-----------PID = 498 TID = 139928822331136 
      3822: java_lock log-----------PID = 498 TID = 139928822331136 
      3824: java_lock log-----------PID = 498 TID = 139928822331136 
      3825: java_lock log-----------PID = 498 TID = 139928822331136 
      3826: java_lock log-----------PID = 498 TID = 139928822331136 
      3827: java_lock log-----------PID = 498 TID = 139928822331136 
      3828: java_lock log-----------PID = 498 TID = 139928822331136 
      3829: java_lock log-----------PID = 498 TID = 139928822331136 
      3830: java_lock log-----------PID = 498 TID = 139928822331136 
      3831: java_lock log-----------PID = 498 TID = 139928822331136 
      3832: java_lock log-----------PID = 498 TID = 139928822331136 
      3833: java_lock log-----------PID = 498 TID = 139928822331136 
      3834: java_lock log-----------PID = 498 TID = 139928822331136 
      3835: java_lock log-----------PID = 498 TID = 139928822331136 
      3836: java_lock log-----------PID = 498 TID = 139928822331136 
      3837: java_lock log-----------PID = 498 TID = 139928822331136 
      3838: java_lock log-----------PID = 498 TID = 139928822331136 
      3839: java_lock log-----------PID = 498 TID = 139928822331136 
      3840: pthread_mutex_lock log  PID = 498 TID = 139928822331136 mutex=0x7f43cc108b28 
      3932: pthread_mutex_lock log  PID = 498 TID = 139928821278464 mutex=0x7f43cc00b728 
      3933: pthread_mutex_lock log  PID = 498 TID = 139928821278464 mutex=0x7f43cc0dd228 
      3938: pthread_mutex_lock log  PID = 498 TID = 139928821278464 mutex=0x7f43cc0dd228 
      3942: pthread_mutex_lock log  PID = 498 TID = 139928821278464 mutex=0x7f43cc079528 
      3945: pthread_mutex_lock log  PID = 498 TID = 139928821278464 mutex=0x7f43cc079528 
      3950: pthread_mutex_lock log  PID = 498 TID = 139928821278464 mutex=0x7f43cc079528 
      3953: java_lock log-----------PID = 498 TID = 139928821278464 
      3954: java_lock log-----------PID = 498 TID = 139928821278464 
      3955: java_lock log-----------PID = 498 TID = 139928821278464 
      3956: java_lock log-----------PID = 498 TID = 139928821278464 
      3957: java_lock log-----------PID = 498 TID = 139928821278464 
      3958: java_lock log-----------PID = 498 TID = 139928821278464 
      3959: java_lock log-----------PID = 498 TID = 139928821278464 
      3960: java_lock log-----------PID = 498 TID = 139928821278464 
      3961: java_lock log-----------PID = 498 TID = 139928821278464 
      3962: java_lock log-----------PID = 498 TID = 139928821278464 
      3963: java_lock log-----------PID = 498 TID = 139928821278464 
      3964: java_lock log-----------PID = 498 TID = 139928821278464 
      3965: java_lock log-----------PID = 498 TID = 139928821278464 
      3966: java_lock log-----------PID = 498 TID = 139928821278464 
      3967: java_lock log-----------PID = 498 TID = 139928821278464 
      3968: java_lock log-----------PID = 498 TID = 139928821278464 
      3969: java_lock log-----------PID = 498 TID = 139928821278464 
      3970: java_lock log-----------PID = 498 TID = 139928821278464 
      3971: java_lock log-----------PID = 498 TID = 139928821278464 
      3972: java_lock log-----------PID = 498 TID = 139928821278464 
      3973: java_lock log-----------PID = 498 TID = 139928821278464 
      3974: java_lock log-----------PID = 498 TID = 139928821278464 
      3975: java_lock log-----------PID = 498 TID = 139928821278464 
      3976: java_lock log-----------PID = 498 TID = 139928821278464 
      3977: java_lock log-----------PID = 498 TID = 139928821278464 
      3978: java_lock log-----------PID = 498 TID = 139928821278464 
      3979: java_lock log-----------PID = 498 TID = 139928821278464 
      3980: java_lock log-----------PID = 498 TID = 139928821278464 
      3981: java_lock log-----------PID = 498 TID = 139928821278464 
      3982: java_lock log-----------PID = 498 TID = 139928821278464 
      3983: java_lock log-----------PID = 498 TID = 139928821278464 
      3984: java_lock log-----------PID = 498 TID = 139928821278464 
      3985: java_lock log-----------PID = 498 TID = 139928821278464 
      3986: java_lock log-----------PID = 498 TID = 139928821278464 
      3987: java_lock log-----------PID = 498 TID = 139928821278464 
      3988: java_lock log-----------PID = 498 TID = 139928821278464 
      3989: java_lock log-----------PID = 498 TID = 139928821278464 
      3990: java_lock log-----------PID = 498 TID = 139928821278464 
      3991: java_lock log-----------PID = 498 TID = 139928821278464 
      3992: java_lock log-----------PID = 498 TID = 139928821278464 
      3993: java_lock log-----------PID = 498 TID = 139928821278464 
      3994: java_lock log-----------PID = 498 TID = 139928821278464 
      3995: java_lock log-----------PID = 498 TID = 139928821278464 
      3996: java_lock log-----------PID = 498 TID = 139928821278464 
      3997: java_lock log-----------PID = 498 TID = 139928821278464 
      3998: java_lock log-----------PID = 498 TID = 139928821278464 
      3999: java_lock log-----------PID = 498 TID = 139928821278464 
      4000: java_lock log-----------PID = 498 TID = 139928821278464 
      4001: java_lock log-----------PID = 498 TID = 139928821278464 
      4002: java_lock log-----------PID = 498 TID = 139928821278464 
      4003: pthread_mutex_lock log  PID = 498 TID = 139928821278464 mutex=0x7f43cc0dd028

6.4 重量级锁

  • 上面的代码，我们2个线程不等待，直接启动
  • 则会再偏向锁的情况下，直接升级到重量级锁

out.log

  • 可以明显看到 系统锁的调用测试变多

    1
    2
    3
    4
    5
    6
    7
    8
    9
    10
    11
    12
    13
    14
    15
    16
    17
    18
    19
    20
    21
    22
    23
    24
    25
    26
    27
    28
    29
    30
    31
    32
    33
    34
    35
    36
    37
    38
    39
    40
    41
    42
    43
    44
    45
    46
    47
    48
    49
    50
    51
    52
    53
    54
    55
    56
    57
    58
    59
    60
    61
    62
    63
    64
    65
    66
    67
    68
    69
    70
    71
    72
    73
    74
    75
    76
    77
    78
    79
    80
    81
    82
    83
    84
    85
    86
    87
    88
    89
    90
    91
    92
    93
    94
    95
    96
    97
    98
    99
    100
    101
    102
    103
    104
    105
    106
    107
    108
    109
    110
    111
    112
    113
    114
    115
    116
    117
    118
    119
    120
    121
    122
    123
    124
    125
    126
    127
    128
    129
    130
    131
    132
    133
    134
    135
    136
    137
    138
    139
    140
    141
    142
    143
    144
    145
    146
    147
    148
    149
    150
    151
    152
    153
    154
    155
    156
    157
    158
    159
    160
    161
    162
    163
    164
    165
    166
    167
    168
    169
    170
    171
    172
    173
    174
    175
    176
    177
    178
    179
    180
    181
    182
    183
    184
    185
    186
    187
    188
    189
    190
    191
    192
    193
    194
    195
    196
    197
    198
    199
    200
    201
    202
    203
    204
    205
    206
    207
    208
    209
    210
    211
    212
    213
    214
    215
    216
    217
    218
    219
    220
    221
    222
    223
    224
    225
    226
    227
    228
    229
    230
    231
    232
    233
    234
    235
    236
    237
    238
    239
    240
    241
    242
    243
    244
    245
    246
    247
    248
    249
    250
    251
    252
    253
    254
    255
    256
    257
    258
    259
    260
    261
    3750: pthread_mutex_lock log  PID = 532 TID = 139648716183296 mutex=0x7f029000b728 
      3751: pthread_mutex_lock log  PID = 532 TID = 139648716183296 mutex=0x7f0290108c28 
      3756: pthread_mutex_lock log  PID = 532 TID = 139648716183296 mutex=0x7f0290108c28 
      3758: pthread_mutex_lock log  PID = 532 TID = 139648647034624 mutex=0x7f029000b728 
      3759: pthread_mutex_lock log  PID = 532 TID = 139648716183296 mutex=0x7f02900b9228 
      3760: pthread_mutex_lock log  PID = 532 TID = 139648647034624 mutex=0x7f029010a528 
      3770: pthread_mutex_lock log  PID = 532 TID = 139648647034624 mutex=0x7f029010a528 
      3775: pthread_mutex_lock log  PID = 532 TID = 139648716183296 mutex=0x7f029d4b28a0 
      3776: pthread_mutex_lock log  PID = 532 TID = 139648716183296 mutex=0x7f029e0fa948 
      3778: java_lock log-----------PID = 532 TID = 139648716183296 
      3784: pthread_mutex_lock log  PID = 532 TID = 139648647034624 mutex=0x7f0290079528 
      3785: pthread_mutex_lock log  PID = 532 TID = 139648647034624 mutex=0x7f029010a528 
      3796: java_lock log-----------PID = 532 TID = 139648716183296 
      3797: pthread_mutex_lock log  PID = 532 TID = 139648647034624 mutex=0x7f029010a528 
      3798: pthread_mutex_lock log  PID = 532 TID = 139648647034624 mutex=0x7f029010a128 
      3799: pthread_mutex_lock log  PID = 532 TID = 139648716183296 mutex=0x7f029010a128 
      3800: java_lock log-----------PID = 532 TID = 139648716183296 
      3801: pthread_mutex_lock log  PID = 532 TID = 139648647034624 mutex=0x7f029010a128 
      3802: pthread_mutex_lock log  PID = 532 TID = 139648647034624 mutex=0x7f029010a128 
      3803: pthread_mutex_lock log  PID = 532 TID = 139648716183296 mutex=0x7f029010a128 
      3804: java_lock log-----------PID = 532 TID = 139648716183296 
      3805: pthread_mutex_lock log  PID = 532 TID = 139648647034624 mutex=0x7f029010a128 
      3806: pthread_mutex_lock log  PID = 532 TID = 139648647034624 mutex=0x7f029010a128 
      3807: pthread_mutex_lock log  PID = 532 TID = 139648716183296 mutex=0x7f029010a128 
      3808: java_lock log-----------PID = 532 TID = 139648716183296 
      3809: pthread_mutex_lock log  PID = 532 TID = 139648647034624 mutex=0x7f029010a128 
      3810: pthread_mutex_lock log  PID = 532 TID = 139648647034624 mutex=0x7f029010a128 
      3811: pthread_mutex_lock log  PID = 532 TID = 139648716183296 mutex=0x7f029010a128 
      3812: java_lock log-----------PID = 532 TID = 139648716183296 
      3813: pthread_mutex_lock log  PID = 532 TID = 139648647034624 mutex=0x7f029010a128 
      3814: pthread_mutex_lock log  PID = 532 TID = 139648647034624 mutex=0x7f029010a128 
      3815: pthread_mutex_lock log  PID = 532 TID = 139648716183296 mutex=0x7f029010a128 
      3816: java_lock log-----------PID = 532 TID = 139648716183296 
      3817: pthread_mutex_lock log  PID = 532 TID = 139648647034624 mutex=0x7f029010a128 
      3818: pthread_mutex_lock log  PID = 532 TID = 139648647034624 mutex=0x7f029010a128 
      3819: pthread_mutex_lock log  PID = 532 TID = 139648716183296 mutex=0x7f029010a128 
      3820: java_lock log-----------PID = 532 TID = 139648716183296 
      3821: pthread_mutex_lock log  PID = 532 TID = 139648647034624 mutex=0x7f029010a128 
      3822: pthread_mutex_lock log  PID = 532 TID = 139648647034624 mutex=0x7f029010a128 
      3823: pthread_mutex_lock log  PID = 532 TID = 139648716183296 mutex=0x7f029010a128 
      3824: java_lock log-----------PID = 532 TID = 139648716183296 
      3825: pthread_mutex_lock log  PID = 532 TID = 139648647034624 mutex=0x7f029010a128 
      3826: pthread_mutex_lock log  PID = 532 TID = 139648647034624 mutex=0x7f029010a128 
      3827: pthread_mutex_lock log  PID = 532 TID = 139648716183296 mutex=0x7f029010a128 
      3828: java_lock log-----------PID = 532 TID = 139648716183296 
      3829: pthread_mutex_lock log  PID = 532 TID = 139648647034624 mutex=0x7f029010a128 
      3830: pthread_mutex_lock log  PID = 532 TID = 139648647034624 mutex=0x7f029010a128 
      3831: pthread_mutex_lock log  PID = 532 TID = 139648716183296 mutex=0x7f029010a128 
      3832: java_lock log-----------PID = 532 TID = 139648716183296 
      3833: pthread_mutex_lock log  PID = 532 TID = 139648647034624 mutex=0x7f029010a128 
      3834: pthread_mutex_lock log  PID = 532 TID = 139648647034624 mutex=0x7f029010a128 
      3835: pthread_mutex_lock log  PID = 532 TID = 139648716183296 mutex=0x7f029010a128 
      3836: java_lock log-----------PID = 532 TID = 139648716183296 
      3837: pthread_mutex_lock log  PID = 532 TID = 139648647034624 mutex=0x7f029010a128 
      3838: pthread_mutex_lock log  PID = 532 TID = 139648647034624 mutex=0x7f029010a128 
      3839: pthread_mutex_lock log  PID = 532 TID = 139648716183296 mutex=0x7f029010a128 
      3840: java_lock log-----------PID = 532 TID = 139648716183296 
      3841: pthread_mutex_lock log  PID = 532 TID = 139648647034624 mutex=0x7f029010a128 
      3842: pthread_mutex_lock log  PID = 532 TID = 139648647034624 mutex=0x7f029010a128 
      3843: pthread_mutex_lock log  PID = 532 TID = 139648716183296 mutex=0x7f029010a128 
      3844: java_lock log-----------PID = 532 TID = 139648716183296 
      3845: pthread_mutex_lock log  PID = 532 TID = 139648647034624 mutex=0x7f029010a128 
      3846: pthread_mutex_lock log  PID = 532 TID = 139648647034624 mutex=0x7f029010a128 
      3847: pthread_mutex_lock log  PID = 532 TID = 139648716183296 mutex=0x7f029010a128 
      3848: java_lock log-----------PID = 532 TID = 139648716183296 
      3849: pthread_mutex_lock log  PID = 532 TID = 139648647034624 mutex=0x7f029010a128 
      3850: pthread_mutex_lock log  PID = 532 TID = 139648647034624 mutex=0x7f029010a128 
      3851: pthread_mutex_lock log  PID = 532 TID = 139648716183296 mutex=0x7f029010a128 
      3852: java_lock log-----------PID = 532 TID = 139648716183296 
      3853: pthread_mutex_lock log  PID = 532 TID = 139648647034624 mutex=0x7f029010a128 
      3854: pthread_mutex_lock log  PID = 532 TID = 139648647034624 mutex=0x7f029010a128 
      3855: pthread_mutex_lock log  PID = 532 TID = 139648716183296 mutex=0x7f029010a128 
      3856: java_lock log-----------PID = 532 TID = 139648716183296 
      3857: pthread_mutex_lock log  PID = 532 TID = 139648647034624 mutex=0x7f029010a128 
      3858: pthread_mutex_lock log  PID = 532 TID = 139648647034624 mutex=0x7f029010a128 
      3859: pthread_mutex_lock log  PID = 532 TID = 139648716183296 mutex=0x7f029010a128 
      3860: java_lock log-----------PID = 532 TID = 139648716183296 
      3861: pthread_mutex_lock log  PID = 532 TID = 139648647034624 mutex=0x7f029010a128 
      3862: pthread_mutex_lock log  PID = 532 TID = 139648647034624 mutex=0x7f029010a128 
      3863: pthread_mutex_lock log  PID = 532 TID = 139648716183296 mutex=0x7f029010a128 
      3864: java_lock log-----------PID = 532 TID = 139648716183296 
      3865: pthread_mutex_lock log  PID = 532 TID = 139648647034624 mutex=0x7f029010a128 
      3866: pthread_mutex_lock log  PID = 532 TID = 139648647034624 mutex=0x7f029010a128 
      3867: pthread_mutex_lock log  PID = 532 TID = 139648716183296 mutex=0x7f029010a128 
      3868: java_lock log-----------PID = 532 TID = 139648716183296 
      3869: pthread_mutex_lock log  PID = 532 TID = 139648647034624 mutex=0x7f029010a128 
      3870: pthread_mutex_lock log  PID = 532 TID = 139648647034624 mutex=0x7f029010a128 
      3871: pthread_mutex_lock log  PID = 532 TID = 139648716183296 mutex=0x7f029010a128 
      3872: java_lock log-----------PID = 532 TID = 139648716183296 
      3873: pthread_mutex_lock log  PID = 532 TID = 139648647034624 mutex=0x7f029010a128 
      3874: pthread_mutex_lock log  PID = 532 TID = 139648647034624 mutex=0x7f029010a128 
      3875: pthread_mutex_lock log  PID = 532 TID = 139648716183296 mutex=0x7f029010a128 
      3876: java_lock log-----------PID = 532 TID = 139648716183296 
      3877: pthread_mutex_lock log  PID = 532 TID = 139648647034624 mutex=0x7f029010a128 
      3878: pthread_mutex_lock log  PID = 532 TID = 139648647034624 mutex=0x7f029010a128 
      3879: pthread_mutex_lock log  PID = 532 TID = 139648716183296 mutex=0x7f029010a128 
      3880: java_lock log-----------PID = 532 TID = 139648716183296 
      3881: pthread_mutex_lock log  PID = 532 TID = 139648647034624 mutex=0x7f029010a128 
      3882: pthread_mutex_lock log  PID = 532 TID = 139648647034624 mutex=0x7f029010a128 
      3883: pthread_mutex_lock log  PID = 532 TID = 139648716183296 mutex=0x7f029010a128 
      3884: java_lock log-----------PID = 532 TID = 139648716183296 
      3885: pthread_mutex_lock log  PID = 532 TID = 139648647034624 mutex=0x7f029010a128 
      3886: pthread_mutex_lock log  PID = 532 TID = 139648647034624 mutex=0x7f029010a128 
      3887: pthread_mutex_lock log  PID = 532 TID = 139648716183296 mutex=0x7f029010a128 
      3888: java_lock log-----------PID = 532 TID = 139648716183296 
      3889: pthread_mutex_lock log  PID = 532 TID = 139648647034624 mutex=0x7f029010a128 
      3890: pthread_mutex_lock log  PID = 532 TID = 139648647034624 mutex=0x7f029010a128 
      3891: pthread_mutex_lock log  PID = 532 TID = 139648716183296 mutex=0x7f029010a128 
      3892: java_lock log-----------PID = 532 TID = 139648716183296 
      3893: pthread_mutex_lock log  PID = 532 TID = 139648647034624 mutex=0x7f029010a128 
      3894: pthread_mutex_lock log  PID = 532 TID = 139648647034624 mutex=0x7f029010a128 
      3895: pthread_mutex_lock log  PID = 532 TID = 139648716183296 mutex=0x7f029010a128 
      3896: java_lock log-----------PID = 532 TID = 139648716183296 
      3897: pthread_mutex_lock log  PID = 532 TID = 139648647034624 mutex=0x7f029010a128 
      3898: pthread_mutex_lock log  PID = 532 TID = 139648647034624 mutex=0x7f029010a128 
      3899: pthread_mutex_lock log  PID = 532 TID = 139648716183296 mutex=0x7f029010a128 
      3900: java_lock log-----------PID = 532 TID = 139648716183296 
      3901: pthread_mutex_lock log  PID = 532 TID = 139648647034624 mutex=0x7f029010a128 
      3902: pthread_mutex_lock log  PID = 532 TID = 139648647034624 mutex=0x7f029010a128 
      3903: pthread_mutex_lock log  PID = 532 TID = 139648716183296 mutex=0x7f029010a128 
      3904: java_lock log-----------PID = 532 TID = 139648716183296 
      3905: pthread_mutex_lock log  PID = 532 TID = 139648647034624 mutex=0x7f029010a128 
      3906: pthread_mutex_lock log  PID = 532 TID = 139648647034624 mutex=0x7f029010a128 
      3907: pthread_mutex_lock log  PID = 532 TID = 139648716183296 mutex=0x7f029010a128 
      3908: java_lock log-----------PID = 532 TID = 139648716183296 
      3909: pthread_mutex_lock log  PID = 532 TID = 139648647034624 mutex=0x7f029010a128 
      3910: pthread_mutex_lock log  PID = 532 TID = 139648647034624 mutex=0x7f029010a128 
      3911: pthread_mutex_lock log  PID = 532 TID = 139648716183296 mutex=0x7f029010a128 
      3912: java_lock log-----------PID = 532 TID = 139648716183296 
      3913: pthread_mutex_lock log  PID = 532 TID = 139648647034624 mutex=0x7f029010a128 
      3914: pthread_mutex_lock log  PID = 532 TID = 139648647034624 mutex=0x7f029010a128 
      3915: pthread_mutex_lock log  PID = 532 TID = 139648716183296 mutex=0x7f029010a128 
      3916: java_lock log-----------PID = 532 TID = 139648716183296 
      3917: pthread_mutex_lock log  PID = 532 TID = 139648647034624 mutex=0x7f029010a128 
      3918: pthread_mutex_lock log  PID = 532 TID = 139648647034624 mutex=0x7f029010a128 
      3919: pthread_mutex_lock log  PID = 532 TID = 139648716183296 mutex=0x7f029010a128 
      3920: java_lock log-----------PID = 532 TID = 139648716183296 
      3921: pthread_mutex_lock log  PID = 532 TID = 139648647034624 mutex=0x7f029010a128 
      3922: pthread_mutex_lock log  PID = 532 TID = 139648647034624 mutex=0x7f029010a128 
      3923: pthread_mutex_lock log  PID = 532 TID = 139648716183296 mutex=0x7f029010a128 
      3924: java_lock log-----------PID = 532 TID = 139648716183296 
      3925: pthread_mutex_lock log  PID = 532 TID = 139648647034624 mutex=0x7f029010a128 
      3926: pthread_mutex_lock log  PID = 532 TID = 139648647034624 mutex=0x7f029010a128 
      3927: pthread_mutex_lock log  PID = 532 TID = 139648716183296 mutex=0x7f029010a128 
      3928: java_lock log-----------PID = 532 TID = 139648716183296 
      3929: pthread_mutex_lock log  PID = 532 TID = 139648647034624 mutex=0x7f029010a128 
      3930: pthread_mutex_lock log  PID = 532 TID = 139648647034624 mutex=0x7f029010a128 
      3931: pthread_mutex_lock log  PID = 532 TID = 139648716183296 mutex=0x7f029010a128 
      3932: java_lock log-----------PID = 532 TID = 139648716183296 
      3933: pthread_mutex_lock log  PID = 532 TID = 139648647034624 mutex=0x7f029010a128 
      3934: pthread_mutex_lock log  PID = 532 TID = 139648647034624 mutex=0x7f029010a128 
      3935: pthread_mutex_lock log  PID = 532 TID = 139648716183296 mutex=0x7f029010a128 
      3936: java_lock log-----------PID = 532 TID = 139648716183296 
      3937: pthread_mutex_lock log  PID = 532 TID = 139648647034624 mutex=0x7f029010a128 
      3938: pthread_mutex_lock log  PID = 532 TID = 139648647034624 mutex=0x7f029010a128 
      3939: pthread_mutex_lock log  PID = 532 TID = 139648716183296 mutex=0x7f029010a128 
      3940: java_lock log-----------PID = 532 TID = 139648716183296 
      3941: pthread_mutex_lock log  PID = 532 TID = 139648647034624 mutex=0x7f029010a128 
      3942: pthread_mutex_lock log  PID = 532 TID = 139648647034624 mutex=0x7f029010a128 
      3943: pthread_mutex_lock log  PID = 532 TID = 139648716183296 mutex=0x7f029010a128 
      3944: java_lock log-----------PID = 532 TID = 139648716183296 
      3945: pthread_mutex_lock log  PID = 532 TID = 139648647034624 mutex=0x7f029010a128 
      3946: pthread_mutex_lock log  PID = 532 TID = 139648647034624 mutex=0x7f029010a128 
      3947: pthread_mutex_lock log  PID = 532 TID = 139648716183296 mutex=0x7f029010a128 
      3948: java_lock log-----------PID = 532 TID = 139648716183296 
      3949: pthread_mutex_lock log  PID = 532 TID = 139648647034624 mutex=0x7f029010a128 
      3950: pthread_mutex_lock log  PID = 532 TID = 139648647034624 mutex=0x7f029010a128 
      3951: pthread_mutex_lock log  PID = 532 TID = 139648716183296 mutex=0x7f029010a128 
      3952: java_lock log-----------PID = 532 TID = 139648716183296 
      3953: pthread_mutex_lock log  PID = 532 TID = 139648647034624 mutex=0x7f029010a128 
      3954: pthread_mutex_lock log  PID = 532 TID = 139648647034624 mutex=0x7f029010a128 
      3955: pthread_mutex_lock log  PID = 532 TID = 139648716183296 mutex=0x7f029010a128 
      3956: java_lock log-----------PID = 532 TID = 139648716183296 
      3957: pthread_mutex_lock log  PID = 532 TID = 139648647034624 mutex=0x7f029010a128 
      3958: pthread_mutex_lock log  PID = 532 TID = 139648647034624 mutex=0x7f029010a128 
      3959: pthread_mutex_lock log  PID = 532 TID = 139648716183296 mutex=0x7f029010a128 
      3960: java_lock log-----------PID = 532 TID = 139648716183296 
      3961: pthread_mutex_lock log  PID = 532 TID = 139648647034624 mutex=0x7f029010a128 
      3962: pthread_mutex_lock log  PID = 532 TID = 139648647034624 mutex=0x7f029010a128 
      3963: pthread_mutex_lock log  PID = 532 TID = 139648716183296 mutex=0x7f029010a128 
      3964: java_lock log-----------PID = 532 TID = 139648716183296 
      3965: pthread_mutex_lock log  PID = 532 TID = 139648647034624 mutex=0x7f029010a128 
      3966: pthread_mutex_lock log  PID = 532 TID = 139648647034624 mutex=0x7f029010a128 
      3967: pthread_mutex_lock log  PID = 532 TID = 139648716183296 mutex=0x7f029010a128 
      3968: java_lock log-----------PID = 532 TID = 139648716183296 
      3969: pthread_mutex_lock log  PID = 532 TID = 139648647034624 mutex=0x7f029010a128 
      3970: pthread_mutex_lock log  PID = 532 TID = 139648647034624 mutex=0x7f029010a128 
      3971: pthread_mutex_lock log  PID = 532 TID = 139648716183296 mutex=0x7f029010a128 
      3972: java_lock log-----------PID = 532 TID = 139648716183296 
      3973: pthread_mutex_lock log  PID = 532 TID = 139648647034624 mutex=0x7f029010a128 
      3974: pthread_mutex_lock log  PID = 532 TID = 139648647034624 mutex=0x7f029010a128 
      3975: pthread_mutex_lock log  PID = 532 TID = 139648716183296 mutex=0x7f029010a128 
      3976: java_lock log-----------PID = 532 TID = 139648716183296 
      3977: pthread_mutex_lock log  PID = 532 TID = 139648647034624 mutex=0x7f029010a128 
      3978: pthread_mutex_lock log  PID = 532 TID = 139648647034624 mutex=0x7f029010a128 
      3979: pthread_mutex_lock log  PID = 532 TID = 139648716183296 mutex=0x7f029010a128 
      3980: java_lock log-----------PID = 532 TID = 139648716183296 
      3981: pthread_mutex_lock log  PID = 532 TID = 139648647034624 mutex=0x7f029010a128 
      3982: pthread_mutex_lock log  PID = 532 TID = 139648647034624 mutex=0x7f029010a128 
      3983: pthread_mutex_lock log  PID = 532 TID = 139648716183296 mutex=0x7f029010a128 
      3984: java_lock log-----------PID = 532 TID = 139648716183296 
      3985: pthread_mutex_lock log  PID = 532 TID = 139648647034624 mutex=0x7f029010a128 
      3986: pthread_mutex_lock log  PID = 532 TID = 139648647034624 mutex=0x7f029010a128 
      3987: pthread_mutex_lock log  PID = 532 TID = 139648716183296 mutex=0x7f029010a128 
      3988: java_lock log-----------PID = 532 TID = 139648716183296 
      3989: pthread_mutex_lock log  PID = 532 TID = 139648647034624 mutex=0x7f029010a128 
      3990: pthread_mutex_lock log  PID = 532 TID = 139648647034624 mutex=0x7f029010a128 
      3991: pthread_mutex_lock log  PID = 532 TID = 139648716183296 mutex=0x7f029010a128 
      3992: pthread_mutex_lock log  PID = 532 TID = 139648716183296 mutex=0x7f0290108a28 
      3993: pthread_mutex_lock log  PID = 532 TID = 139648647034624 mutex=0x7f029010a128 
      3994: java_lock log-----------PID = 532 TID = 139648647034624 
      3995: java_lock log-----------PID = 532 TID = 139648647034624 
      3996: java_lock log-----------PID = 532 TID = 139648647034624 
      3997: java_lock log-----------PID = 532 TID = 139648647034624 
      3998: java_lock log-----------PID = 532 TID = 139648647034624 
      3999: java_lock log-----------PID = 532 TID = 139648647034624 
      4000: java_lock log-----------PID = 532 TID = 139648647034624 
      4001: java_lock log-----------PID = 532 TID = 139648647034624 
      4002: java_lock log-----------PID = 532 TID = 139648647034624 
      4003: java_lock log-----------PID = 532 TID = 139648647034624 
      4004: java_lock log-----------PID = 532 TID = 139648647034624 
      4005: java_lock log-----------PID = 532 TID = 139648647034624 
      4006: java_lock log-----------PID = 532 TID = 139648647034624 
      4007: java_lock log-----------PID = 532 TID = 139648647034624 
      4008: java_lock log-----------PID = 532 TID = 139648647034624 
      4009: java_lock log-----------PID = 532 TID = 139648647034624 
      4010: java_lock log-----------PID = 532 TID = 139648647034624 
      4011: java_lock log-----------PID = 532 TID = 139648647034624 
      4012: java_lock log-----------PID = 532 TID = 139648647034624 
      4013: java_lock log-----------PID = 532 TID = 139648647034624 
      4014: java_lock log-----------PID = 532 TID = 139648647034624 
      4015: java_lock log-----------PID = 532 TID = 139648647034624 
      4016: java_lock log-----------PID = 532 TID = 139648647034624 
      4017: java_lock log-----------PID = 532 TID = 139648647034624 
      4018: java_lock log-----------PID = 532 TID = 139648647034624 
      4019: java_lock log-----------PID = 532 TID = 139648647034624 
      4020: java_lock log-----------PID = 532 TID = 139648647034624 
      4021: java_lock log-----------PID = 532 TID = 139648647034624 
      4022: java_lock log-----------PID = 532 TID = 139648647034624 
      4023: java_lock log-----------PID = 532 TID = 139648647034624 
      4024: java_lock log-----------PID = 532 TID = 139648647034624 
      4025: java_lock log-----------PID = 532 TID = 139648647034624 
      4026: java_lock log-----------PID = 532 TID = 139648647034624 
      4027: java_lock log-----------PID = 532 TID = 139648647034624 
      4028: java_lock log-----------PID = 532 TID = 139648647034624 
      4029: java_lock log-----------PID = 532 TID = 139648647034624 
      4030: java_lock log-----------PID = 532 TID = 139648647034624 
      4031: java_lock log-----------PID = 532 TID = 139648647034624 
      4032: java_lock log-----------PID = 532 TID = 139648647034624 
      4033: java_lock log-----------PID = 532 TID = 139648647034624 
      4034: java_lock log-----------PID = 532 TID = 139648647034624 
      4035: java_lock log-----------PID = 532 TID = 139648647034624 
      4036: java_lock log-----------PID = 532 TID = 139648647034624 
      4037: java_lock log-----------PID = 532 TID = 139648647034624 
      4038: java_lock log-----------PID = 532 TID = 139648647034624 
      4039: java_lock log-----------PID = 532 TID = 139648647034624 
      4040: java_lock log-----------PID = 532 TID = 139648647034624 
      4041: java_lock log-----------PID = 532 TID = 139648647034624 
      4042: java_lock log-----------PID = 532 TID = 139648647034624 
      4043: java_lock log-----------PID = 532 TID = 139648647034624 
      4044: pthread_mutex_lock log  PID = 532 TID = 139648647034624 mutex=0x7f029010a328

    7 总结

  • 无锁，偏向锁，轻量级锁，本质上都JVM层面的锁，除了开始和结束的时候，没有调用系统锁。

  • 重量级锁是需要 系统锁 pthread_mutex_lock 支持的

  • 每个线程50次调用，系统锁的调用次数，我们包括开始和结束

无锁 偏向 轻量级 重量级
线程数量 1 1 2 2
pthread_mutex_lock 调用次数 12 次 12次 14 次 161次
  • 对比 轻量级锁和 重量级锁还是 优化比较大的

8 docker 镜像

如果有需要, 上面

  • docker pull registry.cn-hangzhou.aliyuncs.com/kaiattrib/test:ubuntu16_glibc23
  • 带 jdk
  • 带 glibc23 源码，可编译
  • 带 自己写的一个jni调用库
#

分类

最新文章

标签

Android14
Bug11
C++2
Compose1
Gradle1
JNI2
JSON1
Java23
K8S1
Kotlin4
LeetCode17
Rust1
Spark1
分享1
安装1
搞机1
操作系统1
计组1

目录

×