mirror of https://github.com/alibaba/arthas.git
watch en
LHearen
6 years ago
parent
fe44e00bd1
commit
610ff685bf
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watch
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=====
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Monitor the methods in data aspect including `return value`, `exceptions` and `parameters`.
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With the help of [OGNL](https://en.wikipedia.org/wiki/OGNL), you can easily check the details of the variables.
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### Parameters & Options
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There are four different usage scenarios for `watch` command, which makes it the most complicated command in Arthas.
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|Name|Specification|
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|---:|:---|
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|*class-pattern*|pattern for the class name|
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|*method-pattern*|pattern for the method name|
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|*express*|expression to monitor|
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|*condition-express*|condition expression|
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|[b]|before invoking|
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|[e]|encountering exceptions|
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|[s]|returned normally|
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|[f]|returned normally and abnormally|
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|[E]|turn on regx matching while the default is wildcards matching|
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|[x:]|the depth to print the specified property with default value: 1|
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F.Y.I
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1. any valid OGNL expression as `"{params,returnObj}"` supported
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2. there are four *watching* points: `-b`, `-e`, `-s` and `-f` (the first three are off in default while `-f` on);
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3. at the *watching* point, Arthas will use the `expression` to calculate the values and print them out;
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4. `in-parameters` and `out-parameters` are different since they can be modified; `params` stands for `in-parameters` in `-b`while `out-parameters` in other *watching* points;
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5. there is no `return value` and `exceptions` when using `-b`.
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Advanced:
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* [Critical fields in expression](advice-class.md)
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* [Special usage](https://github.com/alibaba/arthas/issues/71)
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* [OGNL official guide](https://commons.apache.org/proper/commons-ognl/language-guide.html)
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### Usage
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A demo:
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```java
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public void execute() {
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List<String> list = new ArrayList<String>();
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list.add("a");
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list.add("b");
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List<String> list2 = new ArrayList<String>();
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list2.add("c");
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list2.add("d");
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int len = add(list, list2);
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}
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private static int add(List<String> list, List<String> list2) {
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list.addAll(list2);
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return list.size();
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}
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```
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#### Check the `out-parameters`and `return value`
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```shell
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$ watch com.alibaba.sample.petstore.web.store.module.screen.ItemList add "{params,returnObj}" -x 2
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Press Ctrl+C to abort.
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Affect(class-cnt:1 , method-cnt:1) cost in 44 ms.
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@ArrayList[
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@Object[][
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@ArrayList[isEmpty=false;size=4],
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@ArrayList[isEmpty=false;size=2],
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],
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@Integer[4],
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]
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```
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#### Check `in-parameters`
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```shell
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$ watch com.alibaba.sample.petstore.web.store.module.screen.ItemList add "{params,returnObj}" -x 2 -b
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Press Ctrl+C to abort.
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Affect(class-cnt:1 , method-cnt:1) cost in 48 ms.
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@ArrayList[
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@Object[][
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@ArrayList[isEmpty=false;size=2],
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@ArrayList[isEmpty=false;size=2],
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],
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null,
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]
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```
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Compared to the previous *check*:
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1. size of `params[0]` is `2` instead of `4`;
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2. `return value` is `null` since it's `-b`.
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#### Check *before* and *after* at the same time
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```shell
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$ watch com.alibaba.sample.petstore.web.store.module.screen.ItemList add "{params,returnObj}" -x 2 -b -s
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Press Ctrl+C to abort.
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Affect(class-cnt:1 , method-cnt:1) cost in 59 ms.
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@ArrayList[
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@Object[][
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@ArrayList[isEmpty=false;size=2],
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@ArrayList[isEmpty=false;size=2],
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],
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null,
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]
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@ArrayList[
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@Object[][
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@ArrayList[isEmpty=false;size=4],
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@ArrayList[isEmpty=false;size=2],
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],
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@Integer[4],
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]
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```
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F.Y.I
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1. the first block of output is the *before watching* point;
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2. the order of the output determined by the *watching* order itself (nothing to do with the order of the options `-b -s`).
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#### Using `-x` to check more details
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```shell
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$ watch com.alibaba.sample.petstore.web.store.module.screen.ItemList add "{params,returnObj}" -x 3
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Press Ctrl+C to abort.
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Affect(class-cnt:1 , method-cnt:1) cost in 59 ms.
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@ArrayList[
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@Object[][
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@ArrayList[
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@String[a],
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@String[b],
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@String[c],
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@String[d],
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],
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@ArrayList[
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@String[c],
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@String[d],
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],
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],
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@Integer[4],
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]
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```
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#### Using condition expressions to locate specific call
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```shell
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$ watch com.alibaba.sample.petstore.biz.impl.UserManagerImpl testAdd "{params, returnObj}" "params[0].equals('aaa')" -x 2
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Press Ctrl+C to abort.
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Affect(class-cnt:1 , method-cnt:1) cost in 29 ms.
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@ArrayList[
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@Object[][
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@String[aaa],
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@String[bbb],
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],
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@Integer[6],
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]
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```
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#### Check `exceptions`
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```shell
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$ watch com.alibaba.sample.petstore.biz.impl.UserManagerImpl testAdd "{params, throwExp}" -e -x 2
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Press Ctrl+C to abort.
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Affect(class-cnt:1 , method-cnt:1) cost in 29 ms.
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@ArrayList[
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@Object[][
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@String[aaa],
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@String[bbb],
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],
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java.lang.NullPointerException
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at com.alibaba.sample.petstore.biz.impl.UserManagerImpl.testAdd(UserManagerImpl.java:75)
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at com.alibaba.sample.petstore.biz.impl.UserManagerImpl.register(UserManagerImpl.java:60)
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at com.alibaba.sample.petstore.web.user.module.action.RegisterAction.doRegister(RegisterAction.java:45)
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at com.alibaba.sample.petstore.web.user.module.action.RegisterAction$$FastClassByCGLIB$$ad5428f1.invoke(<generated>)
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at net.sf.cglib.reflect.FastMethod.invoke(FastMethod.java:53)
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at com.alibaba.citrus.service.moduleloader.impl.adapter.MethodInvoker.invoke(MethodInvoker.java:70)
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at com.alibaba.citrus.service.moduleloader.impl.adapter.AbstractModuleEventAdapter.executeAndReturn(AbstractModuleEventAdapter.java:100)
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at com.alibaba.citrus.service.moduleloader.impl.adapter.AbstractModuleEventAdapter.execute(AbstractModuleEventAdapter.java:58)
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at com.alibaba.citrus.turbine.pipeline.valve.PerformActionValve.invoke(PerformActionValve.java:63)
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at com.alibaba.citrus.service.pipeline.impl.PipelineImpl$PipelineContextImpl.invokeNext(PipelineImpl.java:157)
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at com.alibaba.citrus.service.pipeline.impl.PipelineImpl$PipelineContextImpl.invoke(PipelineImpl.java:210)
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at com.alibaba.citrus.service.pipeline.impl.valve.ChooseValve.invoke(ChooseValve.java:98)
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at com.alibaba.citrus.service.pipeline.impl.PipelineImpl$PipelineContextImpl.invokeNext(PipelineImpl.java:157)
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at com.alibaba.citrus.service.pipeline.impl.PipelineImpl$PipelineContextImpl.invoke(PipelineImpl.java:210)
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at com.alibaba.citrus.service.pipeline.impl.valve.LoopValve.invokeBody(LoopValve.java:105)
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at com.alibaba.citrus.service.pipeline.impl.valve.LoopValve.invoke(LoopValve.java:83)
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at com.alibaba.citrus.service.pipeline.impl.PipelineImpl$PipelineContextImpl.invokeNext(PipelineImpl.java:157)
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at com.alibaba.citrus.turbine.pipeline.valve.PageAuthorizationValve.invoke(PageAuthorizationValve.java:105)
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at com.alibaba.citrus.service.pipeline.impl.PipelineImpl$PipelineContextImpl.invokeNext(PipelineImpl.java:157)
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at com.alibaba.citrus.turbine.pipeline.valve.CheckCsrfTokenValve.invoke(CheckCsrfTokenValve.java:123)
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at com.alibaba.citrus.service.pipeline.impl.PipelineImpl$PipelineContextImpl.invokeNext(PipelineImpl.java:157)
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at com.alibaba.citrus.turbine.pipeline.valve.AnalyzeURLValve.invoke(AnalyzeURLValve.java:126)
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at com.alibaba.citrus.service.pipeline.impl.PipelineImpl$PipelineContextImpl.invokeNext(PipelineImpl.java:157)
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at com.alibaba.citrus.turbine.pipeline.valve.SetLoggingContextValve.invoke(SetLoggingContextValve.java:66)
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at com.alibaba.citrus.service.pipeline.impl.PipelineImpl$PipelineContextImpl.invokeNext(PipelineImpl.java:157)
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at com.alibaba.citrus.turbine.pipeline.valve.PrepareForTurbineValve.invoke(PrepareForTurbineValve.java:52)
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at com.alibaba.citrus.service.pipeline.impl.PipelineImpl$PipelineContextImpl.invokeNext(PipelineImpl.java:157)
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at com.alibaba.citrus.service.pipeline.impl.PipelineImpl$PipelineContextImpl.invoke(PipelineImpl.java:210)
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at com.alibaba.citrus.webx.impl.WebxControllerImpl.service(WebxControllerImpl.java:43)
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at com.alibaba.citrus.webx.impl.WebxRootControllerImpl.handleRequest(WebxRootControllerImpl.java:53)
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at com.alibaba.citrus.webx.support.AbstractWebxRootController.service(AbstractWebxRootController.java:165)
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at com.alibaba.citrus.webx.servlet.WebxFrameworkFilter.doFilter(WebxFrameworkFilter.java:152)
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at com.alibaba.citrus.webx.servlet.FilterBean.doFilter(FilterBean.java:148)
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at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:241)
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at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:208)
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at com.alibaba.citrus.webx.servlet.SetLoggingContextFilter.doFilter(SetLoggingContextFilter.java:61)
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at com.alibaba.citrus.webx.servlet.FilterBean.doFilter(FilterBean.java:148)
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at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:241)
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at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:208)
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at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:220)
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at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:122)
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at com.taobao.tomcat.valves.ContextLoadFilterValve.invoke(ContextLoadFilterValve.java:152)
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at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:170)
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at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:103)
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at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:116)
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at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:429)
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at org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1085)
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at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:625)
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at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1760)
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at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.run(NioEndpoint.java:1719)
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at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
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at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
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at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)
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at java.lang.Thread.run(Thread.java:745),
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]
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```
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#### Filter based on time cost
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```shell
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$ watch com.alibaba.sample.petstore.web.store.module.screen.ItemList add "{params,returnObj}" #cost>200 -x 3
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Press Ctrl+C to abort.
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Affect(class-cnt:1 , method-cnt:1) cost in 59 ms.
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@ArrayList[
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@Object[][
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@ArrayList[
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@String[a],
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@String[b],
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@String[c],
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@String[d],
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],
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@ArrayList[
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@String[c],
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@String[d],
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],
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],
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@Integer[4],
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]
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```
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F.Y.I
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`#cost>200` (`ms`) filter out all invokings that take less than `200ms`.
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#### Check the global properties of the target object
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`target` stands for the current object.
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```
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$ watch com.taobao.container.web.arthas.rest.MyAppsController myFavoriteApps 'target'
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Press Ctrl+C to abort.
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Affect(class-cnt:1 , method-cnt:1) cost in 128 ms.
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ts=2017-10-31 18:45:55;result=@MyAppsController[
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myFavAppsMapper=@$Proxy131[org.apache.ibatis.binding.MapperProxy@563e97f3],
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getAppNameAndIdByEmpId=@$Proxy135[HardCodedTarget(type=GetAppNameAndIdByEmpId, url=http://hello.com)],
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enableWebConsoleAppsMapper=@$Proxy132[org.apache.ibatis.binding.MapperProxy@7d51e4a8],
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]
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```
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`target.field_name` stands for a global property of the current object.
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```
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$ watch com.taobao.container.web.arthas.rest.MyAppsController myFavoriteApps 'target.myFavAppsMapper'
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Press Ctrl+C to abort.
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Affect(class-cnt:1 , method-cnt:1) cost in 126 ms.
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ts=2017-10-31 18:46:17;result=@$Proxy131[
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m1=@Method[public boolean java.lang.Object.equals(java.lang.Object)],
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m2=@Method[public java.lang.String java.lang.Object.toString()],
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m5=@Method[public abstract java.util.List com.taobao.container.dal.arthas.mapper.MyFavAppsMapper.listFavApps(java.util.Map)],
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m3=@Method[public abstract int com.taobao.container.dal.arthas.mapper.MyFavAppsMapper.delete(java.lang.String,java.lang.String,java.lang.String)],
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m4=@Method[public abstract long com.taobao.container.dal.arthas.mapper.MyFavAppsMapper.insert(com.taobao.container.dal.arthas.domain.MyFavAppsDO)],
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m0=@Method[public native int java.lang.Object.hashCode()],
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]
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```
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