版权声明：杨红岩 https://blog.csdn.net/snxamdf/article/details/89027262
jstack jmap top详解
这篇文章写到命令使用下面介绍三个命令结合使用情况详细说明
这里再介绍一下每个命令作用
- jstack 可查看java进程里的存活线程状态
- jmap 可查看java进程堆内存使用情况
- top linux 命令，可查看java某进程的线程
场景：我们要查看java进程使用cpu资源情况
- 首先使用top命令查看占用cpu高的进程得到pid
- 这里看到java进程45778进程cpu使用率相对较高,下面使用top -Hp 45778列出cpu使用率较高的线程
Processes: 276 total, 2 running, 274 sleeping, 1602 threads 16:55:50
Load Avg: 2.89, 5.07, 4.58 CPU usage: 8.73% user, 7.86% sys, 83.40% idle SharedLibs: 104M resident, 36M data, 94M linkedit.
MemRegions: 95599 total, 2790M resident, 62M private, 702M shared. PhysMem: 8130M used (2043M wired), 61M unused.
VM: 1379G vsize, 1314M framework vsize, 6375177(64) swapins, 6965891(0) swapouts. Networks: packets: 11379450/2746M in, 10750239/1217M out.
Disks: 6755494/97G read, 3489504/81G written.
PID COMMAND %CPU TIME #TH #WQ #PORTS MEM PURG CMPRS PGRP PPID STATE BOOSTS %CPU_ME %CPU_OTHRS UID
45802 top 11.6 00:00.95 1/1 0 25 4392K 0B 0B 45802 44216 running *0[1] 0.00000 0.00000 0
45794 sleep 0.0 00:00.00 1 0 10 240K 0B 0B 45029 45219 sleeping *0[1] 0.00000 0.00000 0
45793 syncdefaults 0.0 00:00.11 2 1 69 3232K 0B 0B 45793 1 sleeping *1[1] 0.00000 0.00000 501
45778 java 0.7 00:02.31 17 1 73 31M+ 0B 0B 43822 43822 sleeping *0[1] 0.00000 0.00000 501
45777 java 0.0 00:07.49 19 1 77 112M 0B 0B 43822 43822 sleeping *0[1] 0.00000 0.00000 501
- top -Hp 45778
Cpu(s): 0.2%us, 0.0%sy, 0.0%ni, 99.8%id, 0.0%wa, 0.0%hi, 0.0%si, 0.0%st
Mem: 3921784k total, 3609916k used, 311868k free, 330264k buffers
Swap: 8191992k total, 0k used, 8191992k free, 1383484k cached
PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND
7348 root 20 0 3588m 1.0g 12m S 0.0 27.5 0:00.00 java
7349 root 20 0 3588m 1.0g 12m S 0.0 27.5 0:01.02 java
7350 root 20 0 3588m 1.0g 12m S 0.0 27.5 0:00.34 java
7351 root 20 0 3588m 1.0g 12m S 0.0 27.5 0:00.40 java
7352 root 20 0 3588m 1.0g 12m S 0.0 27.5 0:00.44 java
7353 root 20 0 3588m 1.0g 12m S 0.0 27.5 0:00.05 java
7354 root 20 0 3588m 1.0g 12m S 0.0 27.5 0:00.05 java
7355 root 20 0 3588m 1.0g 12m S 0.0 27.5 0:00.00 java 上面是在测试服务器拿下的信息，主要是看一下结果，PID 转换为16进制 printf "%x\n" 7348
- jstack 45778 查看进程线程情况
hongyanyang:~ admin$ jstack 48766
2019-04-04 17:58:49
Full thread dump Java HotSpot(TM) 64-Bit Server VM (24.80-b11 mixed mode):
"Attach Listener" daemon prio=5 tid=0x00007ffa262a2800 nid=0xf07 waiting on condition [0x0000000000000000]
java.lang.Thread.State: RUNNABLE
"Service Thread" daemon prio=5 tid=0x00007ffa261fd000 nid=0x4403 runnable [0x0000000000000000]
java.lang.Thread.State: RUNNABLE
"C2 CompilerThread1" daemon prio=5 tid=0x00007ffa261fc800 nid=0x4603 waiting on condition [0x0000000000000000]
java.lang.Thread.State: RUNNABLE
"C2 CompilerThread0" daemon prio=5 tid=0x00007ffa259e3800 nid=0x4803 waiting on condition [0x0000000000000000]
java.lang.Thread.State: RUNNABLE
"Monitor Ctrl-Break" daemon prio=5 tid=0x00007ffa2720f800 nid=0x4903 runnable [0x000070000d4f0000]
java.lang.Thread.State: RUNNABLE
at java.net.SocketInputStream.socketRead0(Native Method)
at java.net.SocketInputStream.read(SocketInputStream.java:152)
at java.net.SocketInputStream.read(SocketInputStream.java:122)
at sun.nio.cs.StreamDecoder.readBytes(StreamDecoder.java:283)
at sun.nio.cs.StreamDecoder.implRead(StreamDecoder.java:325)
at sun.nio.cs.StreamDecoder.read(StreamDecoder.java:177)
- locked <0x00000007d5b38b48> (a java.io.InputStreamReader)
at java.io.InputStreamReader.read(InputStreamReader.java:184)
at java.io.BufferedReader.fill(BufferedReader.java:154)
at java.io.BufferedReader.readLine(BufferedReader.java:317)
- locked <0x00000007d5b38b48> (a java.io.InputStreamReader)
at java.io.BufferedReader.readLine(BufferedReader.java:382)
at com.intellij.rt.execution.application.AppMainV2$1.run(AppMainV2.java:64)
"Signal Dispatcher" daemon prio=5 tid=0x00007ffa26807800 nid=0x4b03 runnable [0x0000000000000000]
java.lang.Thread.State: RUNNABLE
"Finalizer" daemon prio=5 tid=0x00007ffa26809800 nid=0x3003 in Object.wait() [0x000070000d2ea000]
java.lang.Thread.State: WAITING (on object monitor)
at java.lang.Object.wait(Native Method)
- waiting on <0x00000007d5504858> (a java.lang.ref.ReferenceQueue$Lock)
at java.lang.ref.ReferenceQueue.remove(ReferenceQueue.java:135)
- locked <0x00000007d5504858> (a java.lang.ref.ReferenceQueue$Lock)
at java.lang.ref.ReferenceQueue.remove(ReferenceQueue.java:151)
at java.lang.ref.Finalizer$FinalizerThread.run(Finalizer.java:209)
"Reference Handler" daemon prio=5 tid=0x00007ffa27015800 nid=0x2e03 in Object.wait() [0x000070000d1e7000]
java.lang.Thread.State: WAITING (on object monitor)
at java.lang.Object.wait(Native Method)
- waiting on <0x00000007d5504470> (a java.lang.ref.Reference$Lock)
at java.lang.Object.wait(Object.java:503)
at java.lang.ref.Reference$ReferenceHandler.run(Reference.java:133)
- locked <0x00000007d5504470> (a java.lang.ref.Reference$Lock)
"main" prio=5 tid=0x00007ffa27001800 nid=0x1903 waiting on condition [0x000070000cbd5000]
java.lang.Thread.State: TIMED_WAITING (sleeping)
at java.lang.Thread.sleep(Native Method)
at cn.creditease.mammon.TestMain.main(TestMain.java:15)
"VM Thread" prio=5 tid=0x00007ffa2582d000 nid=0x2c03 runnable
"GC task thread#0 (ParallelGC)" prio=5 tid=0x00007ffa2700d800 nid=0x2207 runnable
"GC task thread#1 (ParallelGC)" prio=5 tid=0x00007ffa2700e000 nid=0x2a03 runnable
"GC task thread#2 (ParallelGC)" prio=5 tid=0x00007ffa2700e800 nid=0x5303 runnable
"GC task thread#3 (ParallelGC)" prio=5 tid=0x00007ffa2600f800 nid=0x5103 runnable
"VM Periodic Task Thread" prio=5 tid=0x00007ffa259f4000 nid=0x3703 waiting on condition
JNI global references: 148- 线程状态
- RUNNABLE，线程处于执行中
- BLOCKED，线程被阻塞
- WAITING，线程正在等待
- TIMED_WAITING 指定时间等待
- 信息main线程
- nid 是线程nid 是16进制，上面说的printf "%x\n" xxxx 是为了找到对应的线程就是依据这个nid
- 未完待续....