? 有些時(shí)候我們需要查看jvm的線程執(zhí)行情況睁蕾，如：發(fā)現(xiàn)服務(wù)器的CPU的負(fù)載突然增高了苞笨，出現(xiàn)了死鎖，死循環(huán)子眶，我們?cè)撊绾畏治瞿仄倌窟@個(gè)時(shí)候就要借助jstack命令了，jstack的作用就是將正在運(yùn)行的jvm的線程進(jìn)行快照臭杰，并且打印出來
語法
Usage:
jstack [-l] <pid>
(to connect to running process)
jstack -F [-m] [-l] <pid>
(to connect to a hung process)
jstack [-m] [-l] <executable> <core>
(to connect to a core file)
jstack [-m] [-l] [server_id@]<remote server IP or hostname>
(to connect to a remote debug server)
Options:
-F to force a thread dump. Use when jstack <pid> does not respond (process is hung)
-m to print both java and native frames (mixed mode)
-l long listing. Prints additional information about locks
-h or -help to print this help message
顯示進(jìn)程堆棧
jstack -l pid打印出pid對(duì)應(yīng)的堆棧
jstack檢測(cè)cpu高
步驟一：查看cpu占用高進(jìn)程
top
Mem: 16333644k total, 9472968k used, 6860676k free, 165616k buffers
Swap: 0k total, 0k used, 0k free, 6665292k cached
PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND
17850 root 20 0 7588m 112m 11m S 100.7 0.7 47:53.80 java
1552 root 20 0 121m 13m 8524 S 0.7 0.1 14:37.75 AliYunDun
3581 root 20 0 9750m 2.0g 13m S 0.7 12.9 298:30.20 java
1 root 20 0 19360 1612 1308 S 0.0 0.0 0:00.81 init
2 root 20 0 0 0 0 S 0.0 0.0 0:00.00 kthreadd
3 root RT 0 0 0 0 S 0.0 0.0 0:00.14 migration/0
步驟二：查看cpu占用高線程
top -H -p 17850
top - 17:43:15 up 5 days, 7:31, 1 user, load average: 0.99, 0.97, 0.91
Tasks: 32 total, 1 running, 31 sleeping, 0 stopped, 0 zombie
Cpu(s): 3.7%us, 8.9%sy, 0.0%ni, 87.4%id, 0.0%wa, 0.0%hi, 0.0%si, 0.0%st
Mem: 16333644k total, 9592504k used, 6741140k free, 165700k buffers
Swap: 0k total, 0k used, 0k free, 6781620k cached
PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND
17880 root 20 0 7588m 112m 11m R 99.9 0.7 50:47.43 java
17856 root 20 0 7588m 112m 11m S 0.3 0.7 0:02.08 java
17850 root 20 0 7588m 112m 11m S 0.0 0.7 0:00.00 java
17851 root 20 0 7588m 112m 11m S 0.0 0.7 0:00.23 java
17852 root 20 0 7588m 112m 11m S 0.0 0.7 0:02.09 java
17853 root 20 0 7588m 112m 11m S 0.0 0.7 0:02.12 java
17854 root 20 0 7588m 112m 11m S 0.0 0.7 0:02.07 java
步驟三：轉(zhuǎn)換線程ID
printf "%x\n" 17880
45d8
步驟四：定位cpu占用線程
jstack 17850|grep 45d8 -A 30
"pool-1-thread-11" #20 prio=5 os_prio=0 tid=0x00007fc860352800 nid=0x45d8 runnable [0x00007fc8417d2000]
java.lang.Thread.State: RUNNABLE
at java.io.FileOutputStream.writeBytes(Native Method)
at java.io.FileOutputStream.write(FileOutputStream.java:326)
at java.io.BufferedOutputStream.flushBuffer(BufferedOutputStream.java:82)
at java.io.BufferedOutputStream.flush(BufferedOutputStream.java:140)
- locked <0x00000006c6c2e708> (a java.io.BufferedOutputStream)
at java.io.PrintStream.write(PrintStream.java:482)
- locked <0x00000006c6c10178> (a java.io.PrintStream)
at sun.nio.cs.StreamEncoder.writeBytes(StreamEncoder.java:221)
at sun.nio.cs.StreamEncoder.implFlushBuffer(StreamEncoder.java:291)
at sun.nio.cs.StreamEncoder.flushBuffer(StreamEncoder.java:104)
- locked <0x00000006c6c26620> (a java.io.OutputStreamWriter)
at java.io.OutputStreamWriter.flushBuffer(OutputStreamWriter.java:185)
at java.io.PrintStream.write(PrintStream.java:527)
- eliminated <0x00000006c6c10178> (a java.io.PrintStream)
at java.io.PrintStream.print(PrintStream.java:597)
at java.io.PrintStream.println(PrintStream.java:736)
- locked <0x00000006c6c10178> (a java.io.PrintStream)
at com.demo.guava.HardTask.call(HardTask.java:18)
at com.demo.guava.HardTask.call(HardTask.java:9)
at java.util.concurrent.FutureTask.run(FutureTask.java:266)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
at java.lang.Thread.run(Thread.java:745)
"pool-1-thread-10" #19 prio=5 os_prio=0 tid=0x00007fc860345000 nid=0x45d7 waiting on condition [0x00007fc8418d3000]
java.lang.Thread.State: WAITING (parking)
at sun.misc.Unsafe.park(Native Method)
- parking to wait for <0x00000006c6c14178> (a java.util.concurrent.locks.AbstractQueuedSynchronizer$ConditionObject)
at java.util.concurrent.locks.LockSupport.park(LockSupport.java:175)粤咪。
