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108 lines
3.4 KiB
Plaintext
108 lines
3.4 KiB
Plaintext
classloader
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===========
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View hierarchy, urls and classes-loading info for the class-loaders.
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`classloader` can search and print out the URLs for a specified resource from one particular classloader. It is quite handy when analyze `ResourceNotFoundException`.
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### Options
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|Name|Specification|
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|---:|:---|
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|[l]|list all classloader instances|
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|[t]|print classloader's hierarchy|
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|[a]|list all the classes loaded by all the classloaders (use it with great caution since the output can be huge)|
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|[c:]|print classloader's hashcode|
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|`[c: r:]`|using ClassLoader to search resource|
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|`[c: load:]`|using ClassLoader to load class|
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### Usage
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#### View statistics categorized by class type
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```bash
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$ classloader
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name numberOfInstances loadedCountTotal
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com.taobao.arthas.agent.ArthasClassloader 1 2115
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BootstrapClassLoader 1 1861
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sun.reflect.DelegatingClassLoader 5 5
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sun.misc.Launcher$AppClassLoader 1 4
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sun.misc.Launcher$ExtClassLoader 1 1
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Affect(row-cnt:5) cost in 3 ms.
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```
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#### View statistics categorized by loaded classes number
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```bash
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$ classloader -l
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name loadedCount hash parent
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BootstrapClassLoader 1861 null null
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com.taobao.arthas.agent.ArthasClassloader@68b31f0a 2115 68b31f0a sun.misc.Launcher$ExtClassLoader@66350f69
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sun.misc.Launcher$AppClassLoader@3d4eac69 4 3d4eac69 sun.misc.Launcher$ExtClassLoader@66350f69
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sun.misc.Launcher$ExtClassLoader@66350f69 1 66350f69 null
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Affect(row-cnt:4) cost in 2 ms.
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```
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#### View class-loaders hierarchy
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```bash
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$ classloader -t
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+-BootstrapClassLoader
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+-sun.misc.Launcher$ExtClassLoader@66350f69
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+-com.taobao.arthas.agent.ArthasClassloader@68b31f0a
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+-sun.misc.Launcher$AppClassLoader@3d4eac69
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Affect(row-cnt:4) cost in 3 ms.
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```
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#### Show the URLs of the URLClassLoader
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```bash
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$ classloader -c 3d4eac69
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file:/private/tmp/arthas-demo.jar
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file:/Users/hengyunabc/.arthas/lib/3.0.5/arthas/arthas-agent.jar
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Affect(row-cnt:9) cost in 3 ms.
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```
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#### Use the classloader to load resource
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```bash
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$ classloader -c 3d4eac69 -r META-INF/MANIFEST.MF
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jar:file:/System/Library/Java/Extensions/MRJToolkit.jar!/META-INF/MANIFEST.MF
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jar:file:/private/tmp/arthas-demo.jar!/META-INF/MANIFEST.MF
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jar:file:/Users/hengyunabc/.arthas/lib/3.0.5/arthas/arthas-agent.jar!/META-INF/MANIFEST.MF
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```
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Use the classloader to load `.class` resource
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```shell
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$ classloader -c 1b6d3586 -r java/lang/String.class
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jar:file:/Library/Java/JavaVirtualMachines/jdk1.8.0_60.jdk/Contents/Home/jre/lib/rt.jar!/java/lang/String.class
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```
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#### Use the classloader to load class
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```bash
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$ classloader -c 3d4eac69 --load demo.MathGame
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load class success.
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class-info demo.MathGame
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code-source /private/tmp/arthas-demo.jar
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name demo.MathGame
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isInterface false
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isAnnotation false
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isEnum false
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isAnonymousClass false
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isArray false
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isLocalClass false
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isMemberClass false
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isPrimitive false
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isSynthetic false
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simple-name MathGame
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modifier public
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annotation
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interfaces
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super-class +-java.lang.Object
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class-loader +-sun.misc.Launcher$AppClassLoader@3d4eac69
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+-sun.misc.Launcher$ExtClassLoader@66350f69
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classLoaderHash 3d4eac69
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``` |