Linux性能分析

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生产环境服务器变慢，诊断思路和性能评估

整机：top

代码

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public class JavaDemo2 {
    public static void main(String[] args) {
        while (true){
            System.out.println(new java.util.Random().nextInt(77778888));
        }
    }
}

top命令查看

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[root@192 ~]# top
top - 11:28:50 up 7 min,  2 users,  load average: 0.73, 0.39, 0.18
Tasks: 230 total,   1 running, 229 sleeping,   0 stopped,   0 zombie
Cpu(s):  1.0%us,  2.3%sy,  0.0%ni, 96.7%id,  0.0%wa,  0.0%hi,  0.0%si,  0.0%st
Mem:   1906280k total,   649948k used,  1256332k free,    21164k buffers
Swap:  2097148k total,        0k used,  2097148k free,   203820k cached

   PID USER      PR  NI  VIRT  RES  SHR S %CPU %MEM    TIME+  COMMAND                                                                              
  3672 root      20   0 3158m  94m  11m S 15.6  5.1   0:13.67 java                                                                                 
  3397 root      20   0  100m 5388 3396 S  9.3  0.3   0:09.00 sshd                                                                                 
    39 root      20   0     0    0    0 S  1.7  0.0   0:00.25 events/4                                                                             
    37 root      20   0     0    0    0 S  1.0  0.0   0:00.39 events/2                                                                             
    35 root      20   0     0    0    0 S  0.3  0.0   0:01.27 events/0                                                                             
    36 root      20   0     0    0    0 S  0.3  0.0   0:00.34 events/1                                                                             
    41 root      20   0     0    0    0 S  0.3  0.0   0:00.24 events/6   
[root@192 ~]# uptime
11:29:09 up 7 min,  2 users,  load average: 0.52, 0.36, 0.18

CPU：vmstat

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[root@192 ~]# vmstat -n 2  3
procs -----------memory---------- ---swap-- -----io---- --system-- -----cpu-----
 r  b   swpd   free   buff  cache   si   so    bi    bo   in   cs us sy id wa st
 0  0      0 1313028  21228 203868    0    0    54     3  112 1620  0  1 98  0  0       
 0  0      0 1312732  21228 203896    0    0     0     0 2579 25940  1  3 96  0  0      
 0  0      0 1312856  21228 203896    0    0     0     0 2677 24290  1  3 97  0  0

1564976316953

id:处于空闲的CPU百分比

wa:系统等待IO的CPU时间百分比

st:来自于一个虚拟机偷取的CPU时间百分比

查看额外的CPU信息

所有CPU核信息

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[root@192 ~]# mpstat -P  ALL 2
Linux 2.6.32-642.el6.x86_64 (192.168.1.101)     08/05/2019      _x86_64_        (8 CPU)


11:42:40 AM  CPU    %usr   %nice    %sys %iowait    %irq   %soft  %steal  %guest   %idle
11:42:42 AM  all    1.07    0.00    2.89    0.00    0.00    0.00    0.00    0.00   96.04
11:42:42 AM    0    0.00    0.00    1.52    0.00    0.00    0.00    0.00    0.00   98.48
11:42:42 AM    1    6.09    0.00    9.14    0.00    0.00    0.00    0.00    0.00   84.77
11:42:42 AM    2    0.50    0.00    4.02    0.00    0.00    0.00    0.00    0.00   95.48
11:42:42 AM    3    1.00    0.00    2.00    0.00    0.00    0.00    0.00    0.00   97.00

每个进程使用CPU的用量分解信息

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[root@192 ~]# pidstat -u 1 -p 3790
Linux 2.6.32-642.el6.x86_64 (192.168.1.101)     08/05/2019      _x86_64_        (8 CPU)

11:45:00 AM       PID    %usr %system  %guest    %CPU   CPU  Command
11:45:01 AM      3790    6.00   10.00    0.00   16.00     7  java
11:45:02 AM      3790    4.00   11.00    0.00   15.00     7  java
11:45:03 AM      3790    9.00   15.00    0.00   24.00     7  java
11:45:04 AM      3790    7.00   14.00    0.00   21.00     7  java

内存：free

应用程序可用内存数

推荐使用free -m

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[root@192 ~]# free -g
             total       used       free     shared    buffers     cached
Mem:             1          0          1          0          0          0
-/+ buffers/cache:          0          1
Swap:            1          0          1
[root@192 ~]# free -m
             total       used       free     shared    buffers     cached
Mem:          1861        553       1308          1         20        199
-/+ buffers/cache:        333       1528
Swap:         2047          0       2047

1564976920565

查看额外

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[root@192 ~]# pidstat -p 3823 -r 2
Linux 2.6.32-642.el6.x86_64 (192.168.1.101)     08/05/2019      _x86_64_        (8 CPU)

11:51:16 AM       PID  minflt/s  majflt/s     VSZ    RSS   %MEM  Command
11:51:18 AM      3823      1.00      0.00 3234728  47068   2.47  java
11:51:20 AM      3823      2.50      0.00 3234728  47068   2.47  java
11:51:22 AM      3823      0.50      0.00 3234728  47068   2.47  java
11:51:24 AM      3823      2.50      0.00 3234728  47068   2.47  java
11:51:26 AM      3823      0.50      0.00 3234728  47068   2.47  java

1564977136597

硬盘：df

查看磁盘剩余空间

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[root@192 ~]# df -h
Filesystem      Size  Used Avail Use% Mounted on
/dev/sda2        15G  5.6G  8.4G  41% /
tmpfs           931M   72K  931M   1% /dev/shm
/dev/sda1       190M   39M  142M  22% /boot

磁盘IO：iostat

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[root@192 ~]# iostat -xdk 2 3
Linux 2.6.32-642.el6.x86_64 (192.168.1.101)     08/05/2019      _x86_64_        (8 CPU)

Device:         rrqm/s   wrqm/s     r/s     w/s    rkB/s    wkB/s avgrq-sz avgqu-sz   await r_await w_await  svctm  %util
scd0              0.00     0.00    0.38    0.00     1.50     0.00     8.00     0.00    0.67    0.67    0.00   0.67   0.03
sda              34.33     4.94   47.36    3.18  1631.23    32.44    65.84     0.07    1.38    1.22    3.72   0.88   4.43

Device:         rrqm/s   wrqm/s     r/s     w/s    rkB/s    wkB/s avgrq-sz avgqu-sz   await r_await w_await  svctm  %util
scd0              0.00     0.00    0.00    0.00     0.00     0.00     0.00     0.00    0.00    0.00    0.00   0.00   0.00
sda               0.00     0.00    0.50    0.00     4.00     0.00    16.00     0.00    1.00    1.00    0.00   1.00   0.05

Device:         rrqm/s   wrqm/s     r/s     w/s    rkB/s    wkB/s avgrq-sz avgqu-sz   await r_await w_await  svctm  %util
scd0              0.00     0.00    0.00    0.00     0.00     0.00     0.00     0.00    0.00    0.00    0.00   0.00   0.00
sda               0.00     0.00    0.00    0.00     0.00     0.00     0.00     0.00    0.00    0.00    0.00   0.00   0.00

1564985628042

查看额外

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[root@192 ~]# pidstat -d 2 -p 3485
Linux 2.6.32-642.el6.x86_64 (192.168.1.101)     08/05/2019      _x86_64_        (8 CPU)

02:16:10 PM       PID   kB_rd/s   kB_wr/s kB_ccwr/s  Command
02:16:12 PM      3485      0.00      0.00      0.00  java
02:16:14 PM      3485      0.00      0.00      0.00  java
02:16:16 PM      3485      0.00      0.00      0.00  java
02:16:18 PM      3485      0.00      0.00      0.00  java
02:16:20 PM      3485      0.00      0.00      0.00  java
02:16:22 PM      3485      0.00      0.00      0.00  java
02:16:24 PM      3485      0.00      0.00      0.00  java

1564985817582

网络IO：ifstat

默认本地没有，需要下载ifstat

安装ifstat

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[root@192 ifstat-1.1]# yum install flex byacc  libpcap ncurses ncurses-devel libpcap-devel gcc-c++
wget http://gael.roualland.free.fr/ifstat/ifstat-1.1.tar.gz
tar xzvf ifstat-1.1.tar.gz
cd ifstat-1.1
./configure
make
make install
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[root@192 ifstat-1.1]# ifstat 1
       eth0       
 KB/s in  KB/s out
    0.06      0.13
    0.06      0.12
    0.06      0.12
    0.06      0.12
    0.06      0.12
    0.06      0.12
    0.12      0.17
    0.06      0.12

生产环境出现CPU占用过高，分析思路和定位

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public class JavaDemo2 {
    public static void main(String[] args) {
        while (true){
            System.out.println(new java.util.Random().nextInt(77778888));
        }
    }
}

先用top命令找出CPU占比最高的

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PID USER      PR  NI  VIRT  RES  SHR S %CPU %MEM    TIME+  COMMAND                                                                              
4294 root      20   0 3158m  37m  11m S 16.6  2.0   0:03.28 java                                                                                 
3428 root      20   0  100m 5444 3396 S 14.3  0.3   0:22.85 sshd                                                                                 
  35 root      20   0     0    0    0 S  1.0  0.0   0:03.18 events/0                                                                             
  41 root      20   0     0    0    0 S  0.3  0.0   0:00.52 events/6                                                                             
2012 root      20   0  199m 5192 4288 S  0.3  0.3   0:00.32 ManagementAgent                                                                      
   1 root      20   0 19344 1544 1228 S  0.0  0.1   0:01.83 init                                                                                 
   2 root      20   0     0    0    0 S  0.0  0.0   0:00.02 kthreadd

ps -ef或者jps进一步定位

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[root@192 ifstat-1.1]# jps
4320 Jps
4294 JavaDemo2

定位到具体线程或者代码

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[root@192 ifstat-1.1]# ps -mp 4294 -o THREAD,tid,time
USER     %CPU PRI SCNT WCHAN  USER SYSTEM    TID     TIME
root     18.6   -    - -         -      -      - 00:00:15
root      0.0  19    - futex_    -      -   4294 00:00:00
root     15.6  19    - n_tty_    -      -   4295 00:00:13
root      0.2  19    - futex_    -      -   4296 00:00:00
root      0.2  19    - futex_    -      -   4297 00:00:00
root      0.3  19    - futex_    -      -   4298 00:00:00
root      0.2  19    - futex_    -      -   4299 00:00:00
root      0.3  19    - futex_    -      -   4300 00:00:00
root      0.3  19    - futex_    -      -   4301 00:00:00
root      0.3  19    - futex_    -      -   4302 00:00:00
root      0.2  19    - futex_    -      -   4303 00:00:00
root      0.0  19    - futex_    -      -   4304 00:00:00
root      0.0  19    - futex_    -      -   4305 00:00:00
root      0.0  19    - futex_    -      -   4306 00:00:00
root      0.0  19    - futex_    -      -   4307 00:00:00
root      0.0  19    - futex_    -      -   4308 00:00:00
root      0.1  19    - futex_    -      -   4309 00:00:00
root      0.0  19    - futex_    -      -   4310 00:00:00
root      0.0  19    - futex_    -      -   4311 00:00:00
root      0.0  19    - futex_    -      -   4312 00:00:00
root      0.0  19    - futex_    -      -   4313 00:00:00

-m:显示所有的线程

-p: pid进程使用CPU的时间

-o:该参数后是用户自定义格式

线程ID转换为16进制格式（英文小写格式）

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[root@192 ifstat-1.1]# printf "%x\n" 4295
10c7

jstack 进程ID|grep tid(16进制线程ID小写英文) -A60

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[root@192 ifstat-1.1]# jstack 4294 | grep 10c7 -A60
"main" #1 prio=5 os_prio=0 tid=0x00007f7f68009000 nid=0x10c7 runnable [0x00007f7f6f117000]
   java.lang.Thread.State: RUNNABLE
        at java.io.FileOutputStream.writeBytes(Native Method)
        at java.io.FileOutputStream.write(FileOutputStream.java:326)
        at java.io.BufferedOutputStream.flushBuffer(BufferedOutputStream.java:82)
        at java.io.BufferedOutputStream.flush(BufferedOutputStream.java:140)
        - locked <0x00000000e2e0e6e0> (a java.io.BufferedOutputStream)
        at java.io.PrintStream.write(PrintStream.java:482)
        - locked <0x00000000e2e0bbd8> (a java.io.PrintStream)
        at sun.nio.cs.StreamEncoder.writeBytes(StreamEncoder.java:221)
        at sun.nio.cs.StreamEncoder.implFlushBuffer(StreamEncoder.java:291)
        at sun.nio.cs.StreamEncoder.flushBuffer(StreamEncoder.java:104)
        - locked <0x00000000e2e0e800> (a java.io.OutputStreamWriter)
        at java.io.OutputStreamWriter.flushBuffer(OutputStreamWriter.java:185)
        at java.io.PrintStream.newLine(PrintStream.java:546)
        - eliminated <0x00000000e2e0bbd8> (a java.io.PrintStream)
        at java.io.PrintStream.println(PrintStream.java:737)
        - locked <0x00000000e2e0bbd8> (a java.io.PrintStream)
        at JavaDemo2.main(JavaDemo2.java:4)

"VM Thread" os_prio=0 tid=0x00007f7f68080000 nid=0x10d0 runnable 

"GC task thread#0 (ParallelGC)" os_prio=0 tid=0x00007f7f6801e800 nid=0x10c8 runnable 

"GC task thread#1 (ParallelGC)" os_prio=0 tid=0x00007f7f68020000 nid=0x10c9 runnable 

"GC task thread#2 (ParallelGC)" os_prio=0 tid=0x00007f7f68022000 nid=0x10ca runnable 

"GC task thread#3 (ParallelGC)" os_prio=0 tid=0x00007f7f68024000 nid=0x10cb runnable 

"GC task thread#4 (ParallelGC)" os_prio=0 tid=0x00007f7f68025800 nid=0x10cc runnable 

"GC task thread#5 (ParallelGC)" os_prio=0 tid=0x00007f7f68027800 nid=0x10cd runnable 

"GC task thread#6 (ParallelGC)" os_prio=0 tid=0x00007f7f68029800 nid=0x10ce runnable 

"GC task thread#7 (ParallelGC)" os_prio=0 tid=0x00007f7f6802b000 nid=0x10cf runnable 

"VM Periodic Task Thread" os_prio=0 tid=0x00007f7f680e8000 nid=0x10d9 waiting on condition 

JNI global references: 5

参考

找到最耗CPU的java线程 - - ITeye博客