From 3a270759877ed3398054098806922e820f364e5b Mon Sep 17 00:00:00 2001
From: hengyunabc <hengyunabc@gmail.com>
Date: Fri, 25 Jan 2019 11:44:04 +0800
Subject: [PATCH] update trace doc.

---
 .../arthas/core/command/monitor200/TraceCommand.java |  1 +
 site/src/site/sphinx/en/trace.md                     | 10 ++++++++++
 site/src/site/sphinx/trace.md                        | 12 +++++++++++-
 3 files changed, 22 insertions(+), 1 deletion(-)

diff --git a/core/src/main/java/com/taobao/arthas/core/command/monitor200/TraceCommand.java b/core/src/main/java/com/taobao/arthas/core/command/monitor200/TraceCommand.java
index ce5861896..e08ca3a35 100644
--- a/core/src/main/java/com/taobao/arthas/core/command/monitor200/TraceCommand.java
+++ b/core/src/main/java/com/taobao/arthas/core/command/monitor200/TraceCommand.java
@@ -33,6 +33,7 @@ import java.util.List;
         "  trace *StringUtils isBlank params[0].length==1\n" +
         "  trace *StringUtils isBlank '#cost>100'\n" +
         "  trace -E org\\\\.apache\\\\.commons\\\\.lang\\\\.StringUtils isBlank\n" +
+        "  trace -E com.test.ClassA|org.test.ClassB method1|method2|method3\n" +
         Constants.WIKI + Constants.WIKI_HOME + "trace")
 public class TraceCommand extends EnhancerCommand {
 
diff --git a/site/src/site/sphinx/en/trace.md b/site/src/site/sphinx/en/trace.md
index 05a112921..b3f089a62 100644
--- a/site/src/site/sphinx/en/trace.md
+++ b/site/src/site/sphinx/en/trace.md
@@ -86,3 +86,13 @@ Affect(class-cnt:1 , method-cnt:1) cost in 41 ms.
 * "[min=0.005428ms,max=0.094064ms,total=0.105228ms,count=3] demo:call()" means aggregating all same method calls into one single line. The minimum time cost is `0.005428` ms, the maximum time cost is `0.094064` ms, and the total time cost for all method calls (`3` times in total) to "demo:call()" is `0.105228ms`. If "throws Exception" appears in this line, it means some exceptions have been thrown from this method calls.
 * The total time cost may not equal to the sum of the time costs each sub method call takes, this is because Arthas instrumented code takes time too.
 
+
+#### trace multiple classes or multiple methods
+
+The trace command will only trace the subcalls in the method to the trace, and will not trace down multiple layers. Because traces are expensive, multi-layer traces can lead to a lot of classes and methods that ultimately have to be traced.
+
+You can use the regular expression to match multiple classes and methods on the path to achieve a multi-layer trace effect to some extent.
+
+```bash
+Trace -E com.test.ClassA|org.test.ClassB method1|method2|method3
+```
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diff --git a/site/src/site/sphinx/trace.md b/site/src/site/sphinx/trace.md
index 05ce41a5a..7e0d03201 100644
--- a/site/src/site/sphinx/trace.md
+++ b/site/src/site/sphinx/trace.md
@@ -86,4 +86,14 @@ Affect(class-cnt:1 , method-cnt:1) cost in 41 ms.
 - 是不是很眼熟，没错，在 JProfiler 等收费软件中你曾经见识类似的功能，这里你将可以通过命令就能打印出指定调用路径。 友情提醒下，`trace` 在执行的过程中本身是会有一定的性能开销，在统计的报告中并未像 JProfiler 一样预先减去其自身的统计开销。所以这统计出来有些许的不准，渲染路径上调用的类、方法越多，性能偏差越大。但还是能让你看清一些事情的。
 - [12.033735ms] 的含义，`12.033735` 的含义是：当前节点在当前步骤的耗时，单位为毫秒
 - [0,0,0ms,11]xxx:yyy() [throws Exception]，对该方法中相同的方法调用进行了合并，`0,0,0ms,11` 表示方法调用耗时，`min,max,total,count`；`throws Exception` 表明该方法调用中存在异常返回
-- 这里存在一个统计不准确的问题，就是所有方法耗时加起来可能会小于该监测方法的总耗时，这个是由于 Arthas 本身的逻辑会有一定的耗时
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+- 这里存在一个统计不准确的问题，就是所有方法耗时加起来可能会小于该监测方法的总耗时，这个是由于 Arthas 本身的逻辑会有一定的耗时
+
+#### trace多个类或者多个函数
+
+trace命令只会trace匹配到的函数里的子调用，并不会向下trace多层。因为trace是代价比较贵的，多层trace可能会导致最终要trace的类和函数非常多。
+
+可以用正则表匹配路径上的多个类和函数，一定程度上达到多层trace的效果。
+
+```bash
+trace -E com.test.ClassA|org.test.ClassB method1|method2|method3
+```
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