內(nèi)容源于工作中的總結和網(wǎng)絡搜索。
- 命令找到java線程pid：jps，下面pid是6
root@5pcng:/# jps
6 jar
889 Jps
- 命令查看pid進程下的線程：ps -T -p pid
root@5pcng:/# ps -T -p 6
PID SPID TTY TIME CMD
6 6 ? 00:00:00 java
6 37 ? 00:00:00 Service Thread
6 38 ? 00:00:26 VM Periodic Tas
6 40 ? 00:00:00 logback-1
6 42 ? 00:00:01 mysql-cj-abando
6 47 ? 00:00:01 redisson-netty-
6 80 ? 00:00:03 quartzScheduler
6 112 ? 00:00:00 MyHikariCP hous
6 254 ? 00:00:02 pool-3-thread-1
6 292 ? 00:00:02 pool-3-thread-2
6 299 ? 00:00:01 pool-3-thread-3
6 316 ? 00:00:01 pool-3-thread-4
6 323 ? 00:00:01 pool-3-thread-5
6 330 ? 00:00:01 pool-3-thread-6
6 347 ? 00:00:01 pool-3-thread-7
6 354 ? 00:00:00 pool-3-thread-8
6 361 ? 00:00:01 pool-3-thread-9
只查看線程數(shù)可用：ps -T -p ${pid}| wc -l
root@5pcng:/# ps -T -p 6| wc -l
124
3.查看線程詳細信息：jstack -l pid
root@5pcng:/# jstack -l 6
"C1 CompilerThread8" #13 daemon prio=9 os_prio=0 tid=0x00007fd90c2d0000 nid=0x21 waiting on condition [0x0000000000000000]
java.lang.Thread.State: RUNNABLE
"C2 CompilerThread7" #12 daemon prio=9 os_prio=0 tid=0x00007fd90c2ce000 nid=0x20 waiting on condition [0x0000000000000000]
java.lang.Thread.State: RUNNABLE
"C2 CompilerThread6" #11 daemon prio=9 os_prio=0 tid=0x00007fd90c2cc000 nid=0x1f waiting on condition [0x0000000000000000]
java.lang.Thread.State: RUNNABLE
"C2 CompilerThread5" #10 daemon prio=9 os_prio=0 tid=0x00007fd90c2c9800 nid=0x1e waiting on condition [0x0000000000000000]
java.lang.Thread.State: RUNNABLE
"C2 CompilerThread4" #9 daemon prio=9 os_prio=0 tid=0x00007fd90c2c7800 nid=0x1d waiting on condition [0x0000000000000000]
java.lang.Thread.State: RUNNABLE
"C2 CompilerThread3" #8 daemon prio=9 os_prio=0 tid=0x00007fd90c2bd800 nid=0x1c waiting on condition [0x0000000000000000]
java.lang.Thread.State: RUNNABLE
"VM Periodic Task Thread" os_prio=0 tid=0x00007fd90c2ee800 nid=0x26 waiting on condition
JNI global references: 1955
4.查看jvm內(nèi)存占用及垃圾回收情況：jstat -gcutil pid intervalTime(ms)
root@5pcng:/# jstat -gcutil 6 3000
S0 S1 E O M CCS YGC YGCT FGC FGCT GCT
0.00 99.01 16.04 8.97 94.88 - 15 0.334 3 0.279 0.613
0.00 99.01 16.04 8.97 94.88 - 15 0.334 3 0.279 0.613
0.00 99.01 16.04 8.97 94.88 - 15 0.334 3 0.279 0.613
0.00 99.01 16.04 8.97 94.88 - 15 0.334 3 0.279 0.613
指標說明
S0 : 新生代中Survivor space 0區(qū)已使用空間的百分比
S1: 新生代中Survivor space 1區(qū)已使用空間的百分比
E: 新生代已使用空間的百分比
O: 老年代已使用空間的百分比
M: 元數(shù)據(jù)區(qū)使用比例
CCS：壓縮使用比例
YGC: 從應用程序啟動到當前，發(fā)生Yang GC 的次數(shù)
YGCT: 從應用程序啟動到當前，Yang GC所用的時間【單位秒】
FGC: 從應用程序啟動到當前，發(fā)生Full GC的次數(shù)
FGCT: 從應用程序啟動到當前，F(xiàn)ull GC所用的時間
GCT: 從應用程序啟動到當前，用于垃圾回收的總時間【單位秒】
jstat 選項
class：類加載統(tǒng)計（Displays statistics about the behavior of the class loader.）
compiler：編譯統(tǒng)計（Displays statistics about the behavior of the Java HotSpot VM Just-in-Time compiler.）
gc：垃圾回收統(tǒng)計（Displays statistics about the behavior of the garbage collected heap.）
gccapacity：堆內(nèi)存統(tǒng)計（Displays statistics about the capacities of the generations and their corresponding spaces.
gccause：垃圾回收原因（Displays a summary about garbage collection statistics (same as -gcutil), with the cause of the last and current (when applicable) garbage collection events.）
gcnew：新生代垃圾回收統(tǒng)計（Displays statistics of the behavior of the new generation.）
gcnewcapacity：新生代內(nèi)存統(tǒng)計（Displays statistics about the sizes of the new generations and its corresponding spaces.）
gcold：老年代垃圾回收統(tǒng)計（Displays statistics about the behavior of the old generation and metaspace statistics.）
gcoldcapacity：老年代內(nèi)存統(tǒng)計（Displays statistics about the sizes of the old generation.）
gcmetacapacity：元數(shù)據(jù)空間統(tǒng)計（Displays statistics about the sizes of the metaspace.）
gcutil：總結垃圾回收統(tǒng)計（Displays a summary about garbage collection statistics.）
printcompilation：JVM編譯方法統(tǒng)計（Displays Java HotSpot VM compilation method statistics.）
gccause （推薦使用）
gcutil擁有的輸出列gccause也都擁有，還額外多了最后一次GC原因和當前GC原因。
指標說明：
LGCC：最后一次GC原因（Cause of last garbage collection）
GCC：當前GC原因（Cause of current garbage collection）
