https://docs.oracle.com/javase/8/docs/technotes/tools/unix/jstat.html 官网
Jvm 统计信息 :
类装载,垃圾回收,JIT编译
options :-c|ass, -compi|er, -gc, -printcompilation
printcompilation: Displays Java HotSpot VM compilation method statistics.
类加载
-class
每隔1秒输出一次, 输出10次
就输出一次
-class option
Loaded: Number of classes loaded. 加载了多少类
Bytes: Number of kBs loaded.多大
Unloaded: Number of classes unloaded.卸载了多少类
Bytes: Number of Kbytes unloaded.卸载了多大
Time: Time spent performing class loading and unloading operations.花费在类加载卸载的时间
GC
-gc
这是1.8 永久区已经被移除了
Metaspace为1.8出现
-gccapacity 容量
-gccause GC发生的原因
CCS:短指针, 禁用就没有
CodeCache:JIT编译信息, 禁用就没有
JIT编译信息
-compiler -printcompilation
Compiled: Number of compilation tasks performed.
Failed: Number of compilations tasks failed. 失败的
Invalid: Number of compilation tasks that were invalidated. 无效的
Time: Time spent performing compilation tasks. 花费时间 s
FailedType: Compile type of the last failed compilation.
FailedMethod: Class name and method of the last failed compilation.
