A, install,
Arthas on making a page, the address is alibaba. Making. IO/arthas.
There are several ways to install:
- Download a jar package that can be started and start it in Java-jar mode
- Use the official as.sh script for one-click installation
- Install using RPM
This article introduces the first method because it is simple and super convenient when you want to migrate (after all, you just need to copy the downloaded JAR package).
curl -O https://alibaba.github.io/arthas/arthas-boot.jar
Copy the codeIf the download is too slow, use a source on Gitee
curl -O https://arthas.gitee.io/arthas-boot.jar
Copy the codeThe curl command downloads arthas-boot.jar directly to the directory you want
[root@localhost ~]# ll -lrt
-rw-r--r--. 1 root root 138880 Jun 22 02:55 arthas-boot.jar
Copy the codeSecond, start,
Start directly with a Java command
[root@localhost ~]# java -jar arthas-boot.jar
[INFO] arthas-boot version: 3.33.
[INFO] Can not find java process. Try to pass <pid> in command line.
Please select an available pid.
Copy the codeBut this startup fails because arthas detects the JVM processes running on the machine when it starts up and then lets the user select the process to bind to. The rest is for the selected process.
Here I start with a Java application and then arthas.
[root@localhost ~]# java -jar arthas-boot.jar
[INFO] arthas-boot version: 3.33.
[INFO] Found existing java process, please choose one and input the serial number of the process, eg : 1\. Then hit ENTER.
* [1] :2467 jvm0.01.-SNAPSHOT.jar
Copy the codeHere is a list of Java processes running on the machine, waiting for user input. Type 1 and press Enter. If you need to download some necessary files for the first startup, wait until the download is complete.
[root@localhost arthas]# java -jar arthas-boot.jar
[INFO] arthas-boot version: 3.33.
[INFO] Found existing java process, please choose one and input the serial number of the process, eg : 1\. Then hit ENTER.
* [1] :2467 jvm0.01.-SNAPSHOT.jar
1
[INFO] arthas home: /usr/local/arthas
[INFO] Try to attach process 2467
[INFO] Attach process 2467 success.
[INFO] arthas-client connect 127.0. 01. 3658
,---. ,------. ,--------.,--. ,--. ,---. ,---.
/ O \ | .--. "' -.. -- '| The '-' | / O \ '-'|. -. | |The '-'. '. | | | -. | | - | `. ` - | | | | | | \ \ | | | | | | | | | |. -'| ` --' `--'`--' The '-' `--'` -' `--'`--' `--'` -- -- -- -- --'
wiki https://alibaba.github.io/arthas
tutorials https://alibaba.github.io/arthas/arthas-tutorials
version 3.33.
pid 2467
time 2020- 06- 22 03:02:31
[arthas@2467] $Copy the codeIf you see this screen, it indicates that the association is successful.
Help command
In the ArthAS interactive environment, you can type the help command and all arthAS supported commands will appear
[arthas@2467]$ help
NAME DESCRIPTION
help Display Arthas Help
keymap Display all the available keymap for the specified connection.
sc Search all the classes loaded by JVM
sm Search the method of classes loaded by JVM
classloader Show classloader info
jad Decompile class
getstatic Show the static field of a class.Copy the codeIf you do not know the usage of the command, you can enter the command with the parameter –help, for example, you can see the usage of the sc command
[arthas@2467]$ sc --help
USAGE:
sc [-c <value>] [-d] [-x <value>] [-f] [-h] [-E] class-pattern
SUMMARY:
Search all the classes loaded by JVM
EXAMPLES:
sc -d org.apache.commons.lang.StringUtils
sc -d org/apache/commons/lang/StringUtils
sc -d *StringUtils
sc -d -f org.apache.commons.lang.StringUtils
sc -E org\\.apache\\.commons\\.lang\\.StringUtils
WIKI:
https://alibaba.github.io/arthas/sc
OPTIONS:
-c, --classloader <value> The hash code of the special class's classLoader
-d, -details Display the details of class
-x, -expand <value> Expand level of object (0 by default)
-f, --field Display all the member variables
-h, --help this help
-E, --regex Enable regular expression to match (wildcard matching by default)
<class-pattern> Class name pattern, use either '.' or '/' as separator
Copy the codeNot only does it show what the command is for, the full parameters of the command, but it also provides some specific examples. If you are not used to reading English, you can also go to the address of the WIKI to see the official document, there is a Chinese version.
Arthas (arthas
(1) The CPU usage is too high
Use the thread command to list information about threads
[arthas@2467]$ thread
Threads Total: 28, NEW: 0, RUNNABLE: 11, BLOCKED: 0, WAITING: 14, TIMED_WAITING: 3, TERMINATED: 0
ID NAME GROUP PRIORITY STATE %CPU TIME INTERRUPTE DAEMON
16 http-nio- 8080.-exec2 - main 5 RUNNABLE 99 0:25 false true
29 Attach Listener system 9 RUNNABLE 0 0:0 false true
11 Catalina-utility- 1 main 1 WAITING 0 0:0 false false
12 Catalina-utility2 - main 1 TIMED_WAIT 0 0:0 false false
28 DestroyJavaVM main 5 RUNNABLE 0 0:4 false false
3 Finalizer system 8 WAITING 0 0:0 false true
2 Reference Handler system 10 WAITING 0 0:0 false true
Copy the codeThis command lists all threads in order of CPU usage from highest to lowest. If there are too many threads, you can specify the number of output lines with the -n argument.
Thread id = 16; thread id = 16; thread id = 16; thread id = 16; thread id = 16
[arthas@2467]$ thread 16
"http-nio-8080-exec-2" Id=16 RUNNABLE
at com.spareyaya.jvm.service.EndlessLoopService.service(EndlessLoopService.java:19)
at com.spareyaya.jvm.controller.JVMController.endlessLoop(JVMController.java:30)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)...Copy the codeThe problem was located in two steps
(2) Deadlock
Using thread again, the argument is -b
[arthas@2997]$ thread -b
"Thread-3" Id=29 BLOCKED on java.lang.Object@3f20bf9 owned by "Thread-4" Id=30
at com.spareyaya.jvm.service.DeadLockService.service1(DeadLockService.java:27)
- blocked on java.lang.Object@3f20bf9
- locked java.lang.Object@2fea801a <---- but blocks 1 other threads!
at com.spareyaya.jvm.controller.JVMController.lambda$deadLock$0(JVMController.java:37)
at com.spareyaya.jvm.controller.JVMController$$Lambda$456/748979989.run(Unknown Source)
at java.lang.Thread.run(Thread.java:748)
Copy the codeThis command is as simple as jStack deadlock detection, but I think jStack deadlock detection is a little more intuitive.
(3) Memory leakage
We can use the dashboard command to dynamically check memory usage
If the usage of content is increasing and does not decrease after GC, and gc becomes more frequent later on, it is likely a memory leak.
The heapdump command is used to dump snapshots of the memory, just like jmap
[arthas@23581]$ heapdump --live /root/jvm.hprof
Dumping heap to /root/jvm.hprof...
Heap dump file created
Copy the codeThen import the dump file into Eclipse and use the MAT plugin to analyze it.
Arthas other commands
Arthas also provides many commands for monitoring, such as monitoring the execution time of a method, decompilating class files on the line, and even replacing a class without restarting the Java application. The official usage documentation has been written in too much detail, I will not introduce one by one here, you can try it yourself.
6. Talk about MAT tools
We used the same tool to analyze memory leaks in the previous article and this one — MAT. We have installed the MAT plug-in in Eclipse, which can only be used when opening Eclipse. The problem is that very few mobile Internet companies now use Eclipse as a development tool, and we don’t want to start Eclipse every time we analyze a memory snapshot.
So here are a MAT of independent tool, it is independent of the eclipse, download address is www.eclipse.org/mat/downloa… , you can select the version based on your system.
For example, on Windows, memoryAnalyzer.exe can be started by double-clicking on memoryAnalyzer.exe, and then File->Open Heap Dump… To Open a snapshot file, or click Open a Heap Dump in the Welcome window. If your snapshot file is particularly large and you need to adjust the JVM parameters, modify the MemoryAnalyzer.ini file under Windows to set the -xmx parameter to the appropriate value (the default is 1024M).
As for the commercial version of professional JVM analysis tools like JProfile, you can also go to learn more.