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Posted to notifications@skywalking.apache.org by GitBox <gi...@apache.org> on 2018/04/09 15:44:29 UTC
[GitHub] candyleer opened a new issue #1055: log toolkit may do not take
effect in some case
candyleer opened a new issue #1055: log toolkit may do not take effect in some case
URL: https://github.com/apache/incubator-skywalking/issues/1055
Please answer these questions before submitting your issue.
- Why do you submit this issue?
- [ ] Question or discussion
- [x] Bug
- [ ] Requirement
- [ ] Feature or performance improvement
___
### Question
- What do you want to know?
___
### Bug
- Which version of SkyWalking, OS and JRE?
- Which company or project?
- What happen?
#### Question
when i start an app (called `test_app`) in IDE,i configure the logback file by following this [instruction](https://github.com/apache/incubator-skywalking/blob/master/docs/en/Application-toolkit-logback-1.x.md),but i found it didn't take effect.
i debug this question step by step in `agent` jar. i found the class `org.apache.skywalking.apm.toolkit.log.logback.v1.x.TraceIdPatternLogbackLayout` didn't been transformed.this seems to be strange.what is it happened?
then i put an `break point` in this place,
and see the `debug` stack trace in ide ,Suddenly I understand.
from this picture, we can see that the `TraceIdPatternLogbackLayout` class was loaded in `premain` method,and invoke by `boot` method.but at that time,the `byte buddy instrument` didn't work.because the code is
```
...
ServiceManager.INSTANCE.boot();
...
new AgentBuilder.Default()...
.installOn(instrumentation);
```
that is the class `TraceIdPatternLogbackLayout` loaded is before `instrumentation`.
**this only happens when application code is loaded by `AppClassLoader`,because the `logback.xml` in this classpath.**
in other cases,this code work fine cause their classloader is redefined like `spring boot` or `tomcat` etc. in this cases,the class `TraceIdPatternLogbackLayout` will be loaded only by app code invoke `logger` ,when `agent` started by `AppClassLoader`,it can not see the `logback.xml` config file thus he dont know the class `TraceIdPatternLogbackLayout`,
#### Solution
To resolve this problem ,the simplest way is to change the order of
```
...
ServiceManager.INSTANCE.boot();
...
new AgentBuilder.Default()...
.installOn(instrumentation);
```
to
```
...
new AgentBuilder.Default()...
.installOn(instrumentation);
...
ServiceManager.INSTANCE.boot();
```
that is first invoke `instrumentation` then boot all service in case of the boot service contains some method need to be enhanced.
but i dont know if there has some other problem will be caused?
so please check
___
### Requirement or improvement
- Please describe about your requirements or improvement suggestions.
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