hengyunabc/dumpclass

Dump classes from running JVM process.

Dumpclass

Dump classes from running JVM process by sa-jdi.jar.

• Support wildcard match

• Support multi classloader

Download dumpclass.jar

You can download dumpclass.jar from maven center.

http://search.maven.org/#search%7Cga%7C1%7Cdumpclass

wget http://search.maven.org/remotecontent?filepath=io/github/hengyunabc/dumpclass/0.0.2/dumpclass-0.0.2.jar -O dumpclass.jar

Usage

Usage:
 pattern                  : class name wildcard match pattern
 --noStat                 : do not print dump stat (default: false)
 --sensitive              : class name wildcard match sensitive. In mac os, try
                            this option. (default: false)
 -c (--classLoaderPrefix) : classLoaderPrefix (default: false)
 -o (--outputDir) VAL     : outputDir
 -p (--pid) N             : pid

Example:
  java -jar dumpclass.jar -p 4345 *StringUtils
  java -jar dumpclass.jar -p 4345 -o /tmp/dump *StringUtils
  java -jar dumpclass.jar -p 4345 -o /tmp/dump --classLoaderPrefix  *StringUtils
Use the specified sa-jdi.jar:
  java -cp './dumpclass.jar:$JAVA_HOME/lib/sa-jdi.jar' io.github.hengyunabc.dumpclass.DumpMain 4345 *StringUtils

Trouble

• Try to use sudo

Error attaching to process: sun.jvm.hotspot.debugger.DebuggerException: Can't attach to the process. Could be caused by an incorrect pid or lack of privileges.
sun.jvm.hotspot.debugger.DebuggerException: sun.jvm.hotspot.debugger.DebuggerException: Can't attach to the process. Could be caused by an incorrect pid or lack of privileges.
	at sun.jvm.hotspot.debugger.bsd.BsdDebuggerLocal$BsdDebuggerLocalWorkerThread.execute(BsdDebuggerLocal.java:169)
	at sun.jvm.hotspot.debugger.bsd.BsdDebuggerLocal.attach(BsdDebuggerLocal.java:287)
	at sun.jvm.hotspot.HotSpotAgent.attachDebugger(HotSpotAgent.java:671)
	at sun.jvm.hotspot.HotSpotAgent.setupDebuggerDarwin(HotSpotAgent.java:659)
	at sun.jvm.hotspot.HotSpotAgent.setupDebugger(HotSpotAgent.java:341)
	at sun.jvm.hotspot.HotSpotAgent.go(HotSpotAgent.java:304)
	at sun.jvm.hotspot.HotSpotAgent.attach(HotSpotAgent.java:140)
	at sun.jvm.hotspot.tools.Tool.start(Tool.java:185)
	at sun.jvm.hotspot.tools.Tool.execute(Tool.java:118)
	at sun.jvm.hotspot.tools.jcore.ClassDump.main(ClassDump.java:180)
	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
	at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
	at java.lang.reflect.Method.invoke(Method.java:498)
	at io.github.hengyunabc.dumpclass.DumpMain.run(DumpMain.java:132)
	at io.github.hengyunabc.dumpclass.DumpMain.doMain(DumpMain.java:68)
	at io.github.hengyunabc.dumpclass.DumpMain.main(DumpMain.java:61)
	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
	at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
	at java.lang.reflect.Method.invoke(Method.java:498)
	at io.github.hengyunabc.dumpclass.DumpMain$2.run(DumpMain.java:184)
	at java.lang.Thread.run(Thread.java:745)
Caused by: sun.jvm.hotspot.debugger.DebuggerException: Can't attach to the process. Could be caused by an incorrect pid or lack of privileges.
	at sun.jvm.hotspot.debugger.bsd.BsdDebuggerLocal.attach0(Native Method)
	at sun.jvm.hotspot.debugger.bsd.BsdDebuggerLocal.access$100(BsdDebuggerLocal.java:65)
	at sun.jvm.hotspot.debugger.bsd.BsdDebuggerLocal$1AttachTask.doit(BsdDebuggerLocal.java:278)
	at sun.jvm.hotspot.debugger.bsd.BsdDebuggerLocal$BsdDebuggerLocalWorkerThread.run(BsdDebuggerLocal.java:144)

• Make sure use the same jdk version.

Attaching to process ID 53577, please wait...
Exception in thread "main" java.lang.reflect.InvocationTargetException
	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
	at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
	at java.lang.reflect.Method.invoke(Method.java:497)
	at io.github.hengyunabc.dumpclass.DumpMain.main(DumpMain.java:101)
Caused by: java.lang.InternalError: void* type hasn't been seen when parsing int*
	at sun.jvm.hotspot.HotSpotTypeDataBase.recursiveCreateBasicPointerType(HotSpotTypeDataBase.java:721)
	at sun.jvm.hotspot.HotSpotTypeDataBase.lookupType(HotSpotTypeDataBase.java:134)
	at sun.jvm.hotspot.HotSpotTypeDataBase.lookupOrCreateClass(HotSpotTypeDataBase.java:631)
	at sun.jvm.hotspot.HotSpotTypeDataBase.createType(HotSpotTypeDataBase.java:751)
	at sun.jvm.hotspot.HotSpotTypeDataBase.readVMTypes(HotSpotTypeDataBase.java:195)
	at sun.jvm.hotspot.HotSpotTypeDataBase.<init>(HotSpotTypeDataBase.java:89)
	at sun.jvm.hotspot.HotSpotAgent.setupVM(HotSpotAgent.java:403)
	at sun.jvm.hotspot.HotSpotAgent.go(HotSpotAgent.java:305)
	at sun.jvm.hotspot.HotSpotAgent.attach(HotSpotAgent.java:140)
	at sun.jvm.hotspot.tools.Tool.start(Tool.java:185)
	at sun.jvm.hotspot.tools.Tool.execute(Tool.java:118)
	at sun.jvm.hotspot.tools.jcore.ClassDump.main(ClassDump.java:180)
	... 5 more

• One class loaded by multi ClassLoader

Try to use HSDB. After attach java process, "Tools", "Class Browser".

sudo java -classpath "$JAVA_HOME/lib/sa-jdi.jar" sun.jvm.hotspot.HSDB

complie dumpclass.jar

mvn clean package
ls -alh target

License

Apache License V2

dumpclass's Issues

错误: 找不到或无法加载主类 io.github.hengyunabc.dumpclass.DumpMain

java -cp './dumpclass.jar:$JAVA_HOME/lib/sa-jdi.jar' io.github.hengyunabc.dumpclass.DumpMain

用这个命令提示找不到主类是什么原因？

mac os 下，默认文件系统是不区分大小写的，导致多个类可能会覆盖

比如

com.alibaba.dubbo.common.bytecode.proxy0
com.alibaba.dubbo.common.bytecode.Proxy0

都会写入到同一个文件里。。

增加一个 --sensitive 的选项来精确匹配

想请教一下调ClassDump的main方法时为什么要用反射？

试了一下改回用sun.jvm.hotspot.tools.jcore.ClassDump.main(new String[] { pid }); 直接执行看起来正常情况下也是正常执行，为什么要改成用反射呢？

classLoader.hashCode() 有可能多个classloader 的hashcode一样，使用System#identityHashCode 来避免

改为自动加载sa-jdi.jar

• 首先尝试从当前的ClassLoader里查找，有没有相应的sa-jdi.jar 里的类，如果有，说明用户在 -cp 里指定了sa-jdi.jar，则直接使用即可。
• 如果从当前ClassLoader里查找不到sa-jdi.jar，则尝试用外部自动加载。加载之后，再运行。

jdk 11下面出错

因为即使加了各种的 --add-exports，在 jdk.hotspot.agent 里，是在 sun.jvm.hotspot.tools.jcore.ClassDump.run() 里 ，用Class.forName 来加载filter类的。用户自定义的类加载不到。

    public void run() {
        // Ready to go with the database...
        try {
            if (classFilter == null) {
                // If not already set, the name of the filter comes from a System property.
                // If we have a pkgList, pass it, otherwise let the filter read
                // its own System property for the list of classes.
                String filterClassName = System.getProperty("sun.jvm.hotspot.tools.jcore.filter",
                                                            "sun.jvm.hotspot.tools.jcore.PackageNameFilter");
                try {
                    Class filterClass = Class.forName(filterClassName);
                    if (pkgList == null) {
                        classFilter = (ClassFilter) filterClass.newInstance();
                    } else {
                        Constructor con = filterClass.getConstructor(String.class);
                        classFilter = (ClassFilter) con.newInstance(pkgList);
                    }
                } catch(Exception exp) {
                    System.err.println("Warning: Can not create class filter!");
                }
            }

---

/Library/Java/JavaVirtualMachines/jdk-11.0.4.jdk/Contents/Home/bin/java --add-modules ALL-SYSTEM --add-exports=jdk.hotspot.agent/sun.jvm.hotspot=ALL-UNNAMED --add-exports=jdk.hotspot.agent/sun.jvm.hotspot.runtime=ALL-UNNAMED --add-exports=jdk.hotspot.agent/sun.jvm.hotspot.memory=ALL-UNNAMED --add-exports=jdk.hotspot.agent/sun.jvm.hotspot.oops=ALL-UNNAMED --add-exports=jdk.hotspot.agent/sun.jvm.hotspot.utilities=ALL-UNNAMED --add-exports=jdk.hotspot.agent/sun.jvm.hotspot.tools.jcore=ALL-UNNAMED sun.jvm.hotspot.tools.jcore.ClassDump

http://hengyunabc.github.io/dumpclass/

考虑把 pid 参数放到最后面，不然多次执行命令要改pid时，会比较麻烦

dumpclass时报java.lang.reflect.InvocationTargetException错误

在使用java -jar .\dumpclass.jar -p 26532 com.restful.demo.* -o D:\dump --classLoaderPrefix参数dump class时报如下错误，请问该如何解决，谢谢！

PS D:\QA\AOP-toolbox\tools\dumpclass> java -jar .\dumpclass.jar -p 26532 com.restful.demo.* -o D:\dump --classLoaderPrefix
can not find sa-jdi.jar from classpath, try to load it from java.home.
Attaching to process ID 26532, please wait...
Debugger attached successfully.
Server compiler detected.
JVM version is 25.231-b11
java.lang.reflect.InvocationTargetException
        at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
        at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
        at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
        at java.lang.reflect.Method.invoke(Method.java:498)
        at io.github.hengyunabc.dumpclass.DumpMain$2.run(DumpMain.java:184)
        at java.lang.Thread.run(Thread.java:748)
Caused by: java.lang.reflect.InvocationTargetException
        at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
        at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
        at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
        at java.lang.reflect.Method.invoke(Method.java:498)
        at io.github.hengyunabc.dumpclass.DumpMain.run(DumpMain.java:132)
        at io.github.hengyunabc.dumpclass.DumpMain.doMain(DumpMain.java:68)
        at io.github.hengyunabc.dumpclass.DumpMain.main(DumpMain.java:61)
        ... 6 more
Caused by: java.lang.InternalError
        at sun.jvm.hotspot.tools.jcore.ClassWriter.writeIndex(ClassWriter.java:106)
        at sun.jvm.hotspot.tools.jcore.ClassWriter.writeMethod(ClassWriter.java:550)
        at sun.jvm.hotspot.tools.jcore.ClassWriter.writeMethods(ClassWriter.java:431)
        at sun.jvm.hotspot.tools.jcore.ClassWriter.write(ClassWriter.java:93)
        at io.github.hengyunabc.dumpclass.DumpWrapperFilter.dumpKlass(DumpWrapperFilter.java:99)
        at io.github.hengyunabc.dumpclass.DumpWrapperFilter.canInclude(DumpWrapperFilter.java:31)
        at sun.jvm.hotspot.tools.jcore.ClassDump.dumpKlass(ClassDump.java:138)
        at sun.jvm.hotspot.tools.jcore.ClassDump.access$000(ClassDump.java:38)
        at sun.jvm.hotspot.tools.jcore.ClassDump$1.visit(ClassDump.java:109)
        at sun.jvm.hotspot.memory.Dictionary.classesDo(Dictionary.java:68)
        at sun.jvm.hotspot.memory.SystemDictionary.classesDo(SystemDictionary.java:190)
        at sun.jvm.hotspot.tools.jcore.ClassDump.run(ClassDump.java:105)
        at sun.jvm.hotspot.tools.Tool.startInternal(Tool.java:260)
        at sun.jvm.hotspot.tools.Tool.start(Tool.java:223)
        at sun.jvm.hotspot.tools.Tool.execute(Tool.java:118)
        at sun.jvm.hotspot.tools.jcore.ClassDump.main(ClassDump.java:180)
        ... 13 more

dump出来的文件的权限是 sudo 的权限，需要改进下，不然删除有点麻烦

参考 org.openjdk.jol.vm.sa.ServiceabilityAgentSupport 解决 jdk 9之后的加载问题？

https://github.com/openjdk/jol/blob/0.16/jol-core/src/main/java/org/openjdk/jol/vm/sa/ServiceabilityAgentSupport.java

当有重名类时，会出错

sudo java -jar target/dumpclass.jar 53577 *StringUtils
can not find sa-jdi.jar from classpath, try to load it from java.home.
Attaching to process ID 53577, please wait...
Exception in thread "main" java.lang.reflect.InvocationTargetException
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:497)
    at io.github.hengyunabc.dumpclass.DumpMain.main(DumpMain.java:101)
Caused by: java.lang.InternalError: void* type hasn't been seen when parsing int*
    at sun.jvm.hotspot.HotSpotTypeDataBase.recursiveCreateBasicPointerType(HotSpotTypeDataBase.java:721)
    at sun.jvm.hotspot.HotSpotTypeDataBase.lookupType(HotSpotTypeDataBase.java:134)
    at sun.jvm.hotspot.HotSpotTypeDataBase.lookupOrCreateClass(HotSpotTypeDataBase.java:631)
    at sun.jvm.hotspot.HotSpotTypeDataBase.createType(HotSpotTypeDataBase.java:751)
    at sun.jvm.hotspot.HotSpotTypeDataBase.readVMTypes(HotSpotTypeDataBase.java:195)
    at sun.jvm.hotspot.HotSpotTypeDataBase.<init>(HotSpotTypeDataBase.java:89)
    at sun.jvm.hotspot.HotSpotAgent.setupVM(HotSpotAgent.java:403)
    at sun.jvm.hotspot.HotSpotAgent.go(HotSpotAgent.java:305)
    at sun.jvm.hotspot.HotSpotAgent.attach(HotSpotAgent.java:140)
    at sun.jvm.hotspot.tools.Tool.start(Tool.java:185)
    at sun.jvm.hotspot.tools.Tool.execute(Tool.java:118)
    at sun.jvm.hotspot.tools.jcore.ClassDump.main(ClassDump.java:180)
    ... 5 more

dumpclass 得到的class文件与javac编译得到的class 文件hash存在差异的原因？

1.通过javac HelloWorld.java 得到 class 文件 HelloWorld.class，使用md5的方式得到该class文件Hash值为「A」；通过 dumpclass 的方式从进程中恢复的 HelloWorld.class 文件，使用md5的方式得到该文件Hash值为「B」。
现象：A != B ，想咨询这个问题的原因，为何恢复后程序的class文件不同？
2.如果 java 直接运行通过 dumpclass 得到的class文件，会报错 “Expected stackmap frame at this location”，类似于没有通过JVM验证，但是加上参数 -noverify 就又可以正常运行了。这个实验似乎与上面Hash值不同的现象呼应。想咨询这里面存在某种机制么，类似于JVM运行时保护？

it will be stop the JVM?

if you use sa-jdi.jar to attach JVM and dump classes, it will be the STW?

完善文档，增加没有权限，要sudo的说明