5.2 KiB
Print the logger information, update the logger level
Usage
Print the logger information
logger{{execute T2}}
[arthas@2062]$ logger
name ROOT
class ch.qos.logback.classic.Logger
classLoader org.springframework.boot.loader.LaunchedURLClassLoader@5674cd4d
classLoaderHash 5674cd4d
level INFO
effectiveLevel INFO
additivity true
codeSource jar:file:/home/scrapbook/tutorial/demo-arthas-spring-boot.jar!/BOOT-INF/lib/logback-classi
c-1.1.11.jar!/
appenders name CONSOLE
class ch.qos.logback.core.ConsoleAppender
classLoader org.springframework.boot.loader.LaunchedURLClassLoader@5674cd4d
classLoaderHash 5674cd4d
target System.out
...
View logger information for the special name
logger -n org.springframework.web{{execute T2}}
[arthas@2062]$ logger -n org.springframework.web
name org.springframework.web
class ch.qos.logback.classic.Logger
classLoader org.springframework.boot.loader.LaunchedURLClassLoader@5674cd4d
classLoaderHash 5674cd4d
level null
effectiveLevel INFO
additivity true
codeSource jar:file:/home/scrapbook/tutorial/demo-arthas-spring-boot.jar!/BOOT-INF/lib/logback-classi
c-1.1.11.jar!/
Please write down your classLoaderHash here, in the case here, it's 5674cd4d. It will be used in the future steps.
Note: Please replace <classLoaderHash> with your classLoaderHash above, then execute the commands manually in the following steps:
View logger information for the special classloader
Note that the hashcode changes, you need to check the current ClassLoader information first, and extract the hashcode corresponding to the ClassLoader.
if you use-c, you have to manually type hashcode by -c <hashcode>.
$ logger -c 5674cd4d
For classloader with only one instance, it can be specified by --classLoaderClass using class name, which is more convenient to use.
logger --classLoaderClass org.springframework.boot.loader.LaunchedURLClassLoader{{execute T2}}
[arthas@2062]$ logger --classLoaderClass org.springframework.boot.loader.LaunchedURLClassLoader
name ROOT
class ch.qos.logback.classic.Logger
classLoader org.springframework.boot.loader.LaunchedURLClassLoader@5674cd4d
classLoaderHash 5674cd4d
level INFO
effectiveLevel INFO
additivity true
codeSource jar:file:/home/scrapbook/tutorial/demo-arthas-spring-boot.jar!/BOOT-INF/lib/logback-classi
c-1.1.11.jar!/
appenders name CONSOLE
class ch.qos.logback.core.ConsoleAppender
classLoader org.springframework.boot.loader.LaunchedURLClassLoader@5674cd4d
classLoaderHash 5674cd4d
target System.out
...
The value of --classloaderclass is the class name of classloader. It can only work when it matches a unique classloader instance. The purpose is to facilitate the input of general commands. However, -c <hashcode> is dynamic.
Update logger level
logger --name ROOT --level debug{{execute T2}}
[arthas@2062]$ logger --name ROOT --level debug
update logger level success.
PS: Here it will come up with an error message in tutorial, we have to specify the classloader.
Speecify classloader to update logger level
By default，logger command will be executed under SystemClassloader, if the application is a traditional war, or using spring boot fat jar, then it needs to specify classloader。
You can first use sc -d yourClassName to check specified classloader hashcode，then specify classloader when updating logger level:
logger --classLoaderClass org.springframework.boot.loader.LaunchedURLClassLoader --name ROOT --level debug{{execute T2}}
[arthas@2062]$ logger --classLoaderClass org.springframework.boot.loader.LaunchedURLClassLoader --name ROOT --level debug
View the logger information without appenders
By default, the logger command only prints information about the logger with appenders. If you want to see information about loggers without appender, you can use the parameter --include-no-appender.
Note that the output will usually be very long.
logger --include-no-appender{{execute T2}}
[arthas@2062]$ logger --include-no-appender
name org.thymeleaf
class ch.qos.logback.classic.Logger
classLoader org.springframework.boot.loader.LaunchedURLClassLoader@5674cd4d
classLoaderHash 5674cd4d
level null
effectiveLevel INFO
additivity false
codeSource jar:file:/home/scrapbook/tutorial/demo-arthas-spring-boot.jar!/BOOT-INF/lib/logback-classi
c-1.1.11.jar!/
appenders name DEBUG_LEVEL_REMAPPER
class org.springframework.boot.logging.logback.LevelRemappingAppender
classLoader org.springframework.boot.loader.LaunchedURLClassLoader@5674cd4d
classLoaderHash 5674cd4d
...