Java11使用JVM同一日志框架启用日志记录

你可以使用-Xlog选项配置或启用Java虚拟机同一日志框架的日志记录。

-Xlog:gc*=trace:file=/Users/xx/gc-%t.log:time,tags,level,pid,tid,hostname,path:filecount=3,filesize=10K
-Xlog:gc*=trace:stdout:time,tags,level,pid,tid,hostname:filecount=3,filesize=10K
-Xlog:gc*=trace:stderr:time,tags,level,pid,tid,hostname:filecount=3,filesize=10K

指令格式：

-Xlog[:[what][:[output][:[decorators][:output-options[,...]]]]]

一、what

指定组合的标记和日志级别，格式为tag1[+tag2…][*][=level][, …]。除非制定了通配符（*）,否则只有标记了指定标签的日志消息才会匹配。

-Xlog标记集和日志级别

每条日志消息都有一个级别和一个与之关联的标记集。消息的级别对应于它的详细信息，标记集对应于消息包含的内容或它涉及的JVM组件（如：GC、编译器或线程）。

可用日志级别：

• off
• trace
• debug
• info
• warning
• error

可用的日志标记。指定all而不是标记组合将匹配所有标记组合：

• add
• age
• alloc
• annotation
• aot
• arguments
• attach
• barrier
• biasedlocking
• blocks
• bot
• breakpoint
• bytecode
• census
• class
• classhisto
• cleanup
• compaction
• comparator
• constraints
• constantpool
• coops
• cpu
• cset
• data
• defaultmethods
• dump
• ergo
• event
• exceptions
• exit
• fingerprint
• freelist
• gc
• hashtables
• heap
• humongous
• ihop
• iklass
• init
• itables
• jfr
• jni
• jvmti
• liveness
• load
• loader
• logging
• mark
• marking
• metadata
• metaspace
• method
• mmu
• modules
• monitorinflation
• monitormismatch
• nmethod
• normalize
• objecttagging
• obsolete
• oopmap
• os
• pagesize
• parser
• patch
• path
• phases
• plab
• preorder
• promotion
• protectiondomain
• purge
• redefine
• ref
• refine
• region
• remset
• resolve
• safepoint
• scavenge
• scrub
• setting
• stackmap
• stacktrace
• stackwalk
• start
• startuptime
• state
• stats
• stringdedup
• stringtable
• subclass
• survivor
• sweep
• system
• task
• thread
• time
• timer
• tlab
• unload
• update
• verification
• verify
• vmoperation
• vtables
• workgang

下表描述了标签和日志级别的可能组合列表：

日志标签	描述
-Xlog:gc	Prints the gc information along with time at which the garbage collection occurred.
-Xlog:gc*	Prints log messages that include at least gc tag. It can also have other tags associated with it. However, it will not give phase level information.
-Xlog:gc*=trace	Prints the lowest level of gc logging information. The output displays all gc related tags with detailed logging information.
-Xlog:gc+phases=debug	Prints different phase level information. This gives detailed level of information logged at debug level.
-Xlog:gc+heap=debug	Prints heap usage details before and after gc. This logs messages tagged with the gc and heap at debug level.
-Xlog:safepoint	Prints details about application concurrent time and application stop time at the same level.
-Xlog:gc+ergo*=trace	Prints combination of both gc and ergo messages at trace level. The information includes all details about heap sizing and collection set construction.
-Xlog:gc+age=trace	Prints the survivor size and age distribution of surviving objects in the survivor spaces at trace level.
-Xlog:gc*:file=::filecount=,filesize=	Redirects the output to the file, specifies the number of files you want to use and the size of the file in kb.

二、-Xlog Output

-Xlog选项支持如下三种类型的输出：

• stdout 发送标准输出流到控制台上
• stderr 发送标准错误输出流到控制台上
• file=filename 发送输出到指定的文件

当使用file=filename时,文件名可以指定%p或者%t扩展进程id或者服务启动时的时间，你还可以配置文本文件，以根据文件大小和要归档的文件数量来处理归档。例如，要每10MB归档一次日志文件并保持5个归档文件，指定选项filesize=10M, filecount=5，文件的目标大小不能保证是精确的，它只是一个近似值。文件会归档，最多可以归档5个目标大小为10MB的文件

三、Decorations

日志消息用有关消息的信息装饰。您可以将每个输出配置为使用一组自定义的装饰器。输出的顺序始终与如下表中列出的顺序相同。

装饰器	描述
timeort	Current time and date in ISO-8601 format.
utctimeorutc	Universal Time Coordinated or Coordinated Universal Time.
uptimeoru	Time since the start of the JVM in seconds and milliseconds. For example, 6.567s.
timemillisortm	The same value as generated by System.currentTimeMillis().
uptimemillisorum	Milliseconds since the JVM started.
timenanosortn	The same value generated by System.nanoTime().
uptimenanosorun	Nanoseconds since the JVM started.
hostnameorhn	The host name.
pidorp	The process identifier.
tidorti	The thread identifier.
levelorl	The level associated with the log message.
tagsortg	The tag-set associated with the log message.

四、-Xlog使用案例

• -Xlog 通过使用日志info级别将所有信息记录到stdout输出流，并配置uptime、levels、tags装饰

-Xlog:all=info:stdout:uptime,levels,tags

• -Xlog:gc 使用info级别日志将带有gc标记的消息记录到stdout输出流，对于所有其它级别为warning的消息，默认配置已生效；

参考文档：https://docs.oracle.com/en/java/javase/11/tools/java.html#GUID-BE93ABDC-999C-4CB5-A88B-1994AAAC74D5__TAGSANDLEVELS-A7A4A0DF

开源SDK:https://github.com/mingyang66/spring-parent