JVM之jdk自帶的常用工具命令

1.jps ：jdk中自帶的工具

1.1.概念

jps(Java Virtual Machine Process Status Tool) java虛擬機進程狀態查看工具

我們這裏通過下面的這個springboot項目的啓動腳本去分析 jps不同命令的輸出

 ./copy-gh-third.jar.sh
export JAVA_HOME=/weblogic/jdk1.8.0_181
export JRE_HOME=$JAVA_HOME/jre
export CLASSPATH=.:$JAVA_HOME/lib:$JRE_HOME/lib:$CLASSPATH
export PATH=$JAVA_HOME/bin:$JRE_HOME/bin:$PATH
java -jar -Xmx512m -Xms256m -Duser.timezone=GMT+8:00 gh-third.jar --spring.profiles.active=prd --server.port=7001 --dubbo.registry.group=dubbo/prd  >>  /weblogic/bea/user_projects/domains/third/logs/wls.log 2>&1 &
echo "gh-third-spring-boot starting ..."

1.2.jps -q :只輸出進程 ID

1.3.jps -m :輸出傳入 main 方法的參數

1.4.jps -l :輸出完全的包名，應用主類名，jar的完全路徑名

[weblogic@iZzm07uu28d7wcuv8t6ms3Z third]$ jps -l
34124 gh-third.jar
47089 sun.tools.jps.Jps
[weblogic@iZzm07uu28d7wcuv8t6ms3Z third]$ 

1.5.jps -v :輸出jvm參數

[weblogic@iZzm07uu28d7wcuv8t6ms3Z third]$ jps -v
47877 Jps -Dapplication.home=/weblogic/jdk1.7.0_80 -Xms8m
34124 jar -Xmx512m -Xms256m -Duser.timezone=GMT+8:00
[weblogic@iZzm07uu28d7wcuv8t6ms3Z third]$ 

2.jinfo：jdk中自帶的工具

2.1.概念

1.jinfo主要是打印java虛擬機的參數以及動態修改java虛擬機參數
2.jinfo使用，一般是與上面jps一起使用的，因爲jinfo的使用需要知道進程的ip(process id)，當然如果你有其他方式可以知道進程的id
  也是可以替代jps的使用的;

2.2.查看某個進程的某個屬性的值:jinfo -flag ${jvm-property-name} ${pid}

jinfo -flag MaxHeapSize 19337 查看進程19337 最大堆內存設置

[weblogic@10_32_69_84 ~]$ jps -ml
19337 gh-third.jar --spring.profiles.active=dat --server.port=7005 --dubbo.registry.group=dubbo/dat --debug
27875 weblogic.Server
6284 sun.tools.jps.Jps -ml
20458 weblogic.Server
[weblogic@10_32_69_84 ~]$ 
[weblogic@10_32_69_84 ~]$ jinfo -flag MaxHeapSize 19337
-XX:MaxHeapSize=2147483648
[weblogic@10_32_69_84 ~]$ 

2.3.查看某個進程的所有屬性的值:jinfo -flags ${pid}

2.4.修改某個進程的所有屬性的值:jinfo -flag [+/-] ${jvm-property-name} ${pid}

這裏注意下，只有標記位manageable的屬性纔可以被修改

設置

localhost:~ gaoxinfu$ jps -ml
66626 sun.tools.jps.Jps -ml
63910 org.jetbrains.idea.maven.server.RemoteMavenServer
63720 
66569 org.jetbrains.jps.cmdline.Launcher /Applications/IntelliJ IDEA.app/Contents/lib/plexus-component-annotations-1.6.jar:/Applications/IntelliJ IDEA.app/Contents/lib/asm-all-7.0.1.jar:/Applications/IntelliJ IDEA.app/Contents/lib/aether-api-1.1.0.jar:/Applications/IntelliJ IDEA.app/Contents/lib/aether-transport-http-1.1.0.jar:/Applications/IntelliJ IDEA.app/Contents/lib/aether-util-1.1.0.jar:/Applications/IntelliJ IDEA.app/Contents/lib/lz4-1.3.0.jar:/Applications/IntelliJ IDEA.app/Contents/lib/httpcore-4.4.10.jar:/Applications/IntelliJ IDEA.app/Contents/lib/netty-buffer-4.1.32.Final.jar:/Applications/IntelliJ IDEA.app/Contents/lib/guava-25.1-jre.jar:/Applications/IntelliJ IDEA.app/Contents/lib/netty-transport-4.1.32.Final.jar:/Applications/IntelliJ IDEA.app/Contents/lib/util.jar:/Applications/IntelliJ IDEA.app/Contents/lib/platform-api.jar:/Applications/IntelliJ IDEA.app/Contents/lib/plexus-interpolation-1.21.jar:/Applications/IntelliJ IDEA.app/Contents/lib/aether-spi-1.1.0.jar:/Applications/IntelliJ IDEA.app/Cont
66570 com.gaoxinfu.demo.jvm.DemoJvmApplication
localhost:~ gaoxinfu$ jinfo -flag +HeapDumpAfterFullGC 66570 
localhost:~ gaoxinfu$ 

查看 +HeapDumpAfterFullGC 標示已經開啓了

localhost:~ gaoxinfu$ jinfo -flag HeapDumpAfterFullGC 66570
-XX:+HeapDumpAfterFullGC
localhost:~ gaoxinfu$ 

2.5.修改某個進程的所有屬性的值:jinfo -flag ${jvm-property-name}=${value} ${pid}

設置

localhost:~ gaoxinfu$ jps -ml
66626 sun.tools.jps.Jps -ml
63910 org.jetbrains.idea.maven.server.RemoteMavenServer
63720 
66569 org.jetbrains.jps.cmdline.Launcher /Applications/IntelliJ IDEA.app/Contents/lib/plexus-component-annotations-1.6.jar:/Applications/IntelliJ IDEA.app/Contents/lib/asm-all-7.0.1.jar:/Applications/IntelliJ IDEA.app/Contents/lib/aether-api-1.1.0.jar:/Applications/IntelliJ IDEA.app/Contents/lib/aether-transport-http-1.1.0.jar:/Applications/IntelliJ IDEA.app/Contents/lib/aether-util-1.1.0.jar:/Applications/IntelliJ IDEA.app/Contents/lib/lz4-1.3.0.jar:/Applications/IntelliJ IDEA.app/Contents/lib/httpcore-4.4.10.jar:/Applications/IntelliJ IDEA.app/Contents/lib/netty-buffer-4.1.32.Final.jar:/Applications/IntelliJ IDEA.app/Contents/lib/guava-25.1-jre.jar:/Applications/IntelliJ IDEA.app/Contents/lib/netty-transport-4.1.32.Final.jar:/Applications/IntelliJ IDEA.app/Contents/lib/util.jar:/Applications/IntelliJ IDEA.app/Contents/lib/platform-api.jar:/Applications/IntelliJ IDEA.app/Contents/lib/plexus-interpolation-1.21.jar:/Applications/IntelliJ IDEA.app/Contents/lib/aether-spi-1.1.0.jar:/Applications/IntelliJ IDEA.app/Cont
66570 com.gaoxinfu.demo.jvm.DemoJvmApplication
localhost:~ gaoxinfu$ jinfo -flag CMSWaitDuration=3000 66570
localhost:~ gaoxinfu$ 

查看

localhost:~ gaoxinfu$ jinfo -flag CMSWaitDuration 66570
-XX:CMSWaitDuration=3000
localhost:~ gaoxinfu$ 

3.jstat

官網使用地址介紹
https://docs.oracle.com/javase/9/tools/jstat.htm#JSWOR734

jstat命令可以查看堆內存各部分的使用量，以及加載類的數量。
命令的格式如下：
jstat [-命令選項類型] [pid] [間隔時間/毫秒] [查詢次數]
這裏注意下 [間隔時間/毫秒] [查詢次數] 這些是可選的，意味着不寫，只會輸出一次;

3.1.類加載信息:jstat -class 66570 1000 10

localhost:~ gaoxinfu$ jps -ml
63910 org.jetbrains.idea.maven.server.RemoteMavenServer
63720 
66569 org.jetbrains.jps.cmdline.Launcher /Applications/IntelliJ IDEA.app/Contents/lib/plexus-component-annotations-1.6.jar:/Applications/IntelliJ IDEA.app/Contents/lib/asm-all-7.0.1.jar:/Applications/IntelliJ IDEA.app/Contents/lib/aether-api-1.1.0.jar:/Applications/IntelliJ IDEA.app/Contents/lib/aether-transport-http-1.1.0.jar:/Applications/IntelliJ IDEA.app/Contents/lib/aether-util-1.1.0.jar:/Applications/IntelliJ IDEA.app/Contents/lib/lz4-1.3.0.jar:/Applications/IntelliJ IDEA.app/Contents/lib/httpcore-4.4.10.jar:/Applications/IntelliJ IDEA.app/Contents/lib/netty-buffer-4.1.32.Final.jar:/Applications/IntelliJ IDEA.app/Contents/lib/guava-25.1-jre.jar:/Applications/IntelliJ IDEA.app/Contents/lib/netty-transport-4.1.32.Final.jar:/Applications/IntelliJ IDEA.app/Contents/lib/util.jar:/Applications/IntelliJ IDEA.app/Contents/lib/platform-api.jar:/Applications/IntelliJ IDEA.app/Contents/lib/plexus-interpolation-1.21.jar:/Applications/IntelliJ IDEA.app/Contents/lib/aether-spi-1.1.0.jar:/Applications/IntelliJ IDEA.app/Cont
66570 com.gaoxinfu.demo.jvm.DemoJvmApplication
74511 sun.tools.jps.Jps -ml
localhost:~ gaoxinfu$ jstat -class 66570 1000 10
Loaded  Bytes  Unloaded  Bytes     Time   
  6339 11588.7        0     0.0       5.89
  6339 11588.7        0     0.0       5.89
  6339 11588.7        0     0.0       5.89
  6339 11588.7        0     0.0       5.89
  6339 11588.7        0     0.0       5.89
  6339 11588.7        0     0.0       5.89
  6339 11588.7        0     0.0       5.89
  6339 11588.7        0     0.0       5.89
  6339 11588.7        0     0.0       5.89
  6339 11588.7        0     0.0       5.89
localhost:~ gaoxinfu$ 

Loaded:加載class的數量
Bytes：所佔用空間大小
Unloaded：未加載數量
Bytes:未加載佔用空間
Time：時間

3.2.垃圾回收:jstat -gc 66570 1000 5

localhost:~ gaoxinfu$ jstat -gc 66570 1000 5
 S0C    S1C    S0U    S1U      EC       EU        OC         OU       MC     MU    CCSC   CCSU   YGC     YGCT    FGC    FGCT     GCT   
9728.0 11264.0 9721.8  0.0   45568.0   6382.5   68608.0     9036.8   34688.0 32983.1 4480.0 4172.8      8    0.065   1      0.050    0.115
9728.0 11264.0 9721.8  0.0   45568.0   6382.5   68608.0     9036.8   34688.0 32983.1 4480.0 4172.8      8    0.065   1      0.050    0.115
9728.0 11264.0 9721.8  0.0   45568.0   6382.5   68608.0     9036.8   34688.0 32983.1 4480.0 4172.8      8    0.065   1      0.050    0.115
9728.0 11264.0 9721.8  0.0   45568.0   6382.5   68608.0     9036.8   34688.0 32983.1 4480.0 4172.8      8    0.065   1      0.050    0.115
9728.0 11264.0 9721.8  0.0   45568.0   6382.5   68608.0     9036.8   34688.0 32983.1 4480.0 4172.8      8    0.065   1      0.050    0.115
localhost:~ gaoxinfu$ 

S0C：第一個倖存區的大小
S1C：第二個倖存區的大小
S0U：第一個倖存區的使用大小
S1U：第二個倖存區的使用大小
EC：伊甸園區的大小
EU：伊甸園區的使用大小
OC：老年代大小
OU：老年代使用大小
MC：方法區大小
MU：方法區使用大小
CCSC:壓縮類空間大小
CCSU:壓縮類空間使用大小
YGC：年輕代垃圾回收次數
YGCT：年輕代垃圾回收消耗時間
FGC：老年代垃圾回收次數
FGCT：老年代垃圾回收消耗時間
GCT：垃圾回收消耗總時間

3.3.堆內存統計:jstat -gccapacity 66570 1000 5

localhost:~ gaoxinfu$ jstat -gccapacity 66570 1000 5
 NGCMN    NGCMX     NGC     S0C   S1C       EC      OGCMN      OGCMX       OGC         OC       MCMN     MCMX      MC     CCSMN    CCSMX     CCSC    YGC    FGC 
 33792.0  68096.0  68096.0 9728.0 11264.0  45568.0    68608.0   136704.0    68608.0    68608.0      0.0 1079296.0  34688.0      0.0 1048576.0   4480.0      8     1
 33792.0  68096.0  68096.0 9728.0 11264.0  45568.0    68608.0   136704.0    68608.0    68608.0      0.0 1079296.0  34688.0      0.0 1048576.0   4480.0      8     1
 33792.0  68096.0  68096.0 9728.0 11264.0  45568.0    68608.0   136704.0    68608.0    68608.0      0.0 1079296.0  34688.0      0.0 1048576.0   4480.0      8     1
 33792.0  68096.0  68096.0 9728.0 11264.0  45568.0    68608.0   136704.0    68608.0    68608.0      0.0 1079296.0  34688.0      0.0 1048576.0   4480.0      8     1
 33792.0  68096.0  68096.0 9728.0 11264.0  45568.0    68608.0   136704.0    68608.0    68608.0      0.0 1079296.0  34688.0      0.0 1048576.0   4480.0      8     1
localhost:~ gaoxinfu$ 

NGCMN：新生代最小容量
NGCMX：新生代最大容量
NGC：當前新生代容量
S0C：第一個倖存區大小
S1C：第二個倖存區的大小
EC：伊甸園區的大小
OGCMN：老年代最小容量
OGCMX：老年代最大容量
OGC：當前老年代大小
OC:當前老年代大小
MCMN:最小元數據容量
MCMX：最大元數據容量
MC：當前元數據空間大小
CCSMN：最小壓縮類空間大小
CCSMX：最大壓縮類空間大小
CCSC：當前壓縮類空間大小
YGC：年輕代gc次數
FGC：老年代GC次數

3.4.新生代垃圾回收統計:jstat -gcnew 66570

localhost:~ gaoxinfu$ jstat -gcnew 66570
 S0C    S1C    S0U    S1U   TT MTT  DSS      EC       EU     YGC     YGCT  
9728.0 11264.0 9721.8    0.0  6  15 11264.0  45568.0   7293.9      8    0.065
localhost:~ gaoxinfu$ 

S0C：第一個倖存區大小
S1C：第二個倖存區的大小
S0U：第一個倖存區的使用大小
S1U：第二個倖存區的使用大小
TT:對象在新生代存活的次數
MTT:對象在新生代存活的最大次數
DSS:期望的倖存區大小
EC：伊甸園區的大小
EU：伊甸園區的使用大小
YGC：年輕代垃圾回收次數
YGCT：年輕代垃圾回收消耗時間

3.5.新生代內存統計:jstat -gcnewcapacity 66570

localhost:~ gaoxinfu$ jstat -gcnewcapacity 66570
  NGCMN      NGCMX       NGC      S0CMX     S0C     S1CMX     S1C       ECMX        EC      YGC   FGC 
   33792.0    68096.0    68096.0  22528.0   9728.0  22528.0  11264.0    67072.0    45568.0     8     1
localhost:~ gaoxinfu$ 

NGCMN：新生代最小容量
NGCMX：新生代最大容量
NGC：當前新生代容量
S0CMX：最大幸存1區大小
S0C：當前倖存1區大小
S1CMX：最大幸存2區大小
S1C：當前倖存2區大小
ECMX：最大伊甸園區大小
EC：當前伊甸園區大小
YGC：年輕代垃圾回收次數
FGC：老年代回收次數

3.6.老年代垃圾回收統計:jstat -gcold 66570

localhost:~ gaoxinfu$ jstat -gcold 66570
   MC       MU      CCSC     CCSU       OC          OU       YGC    FGC    FGCT     GCT   
 34688.0  32983.1   4480.0   4172.8     68608.0      9036.8      8     1    0.050    0.115
localhost:~ gaoxinfu$ 

MC：方法區大小
MU：方法區使用大小
CCSC:壓縮類空間大小
CCSU:壓縮類空間使用大小
OC：老年代大小
OU：老年代使用大小
YGC：年輕代垃圾回收次數
FGC：老年代垃圾回收次數
FGCT：老年代垃圾回收消耗時間
GCT：垃圾回收消耗總時間

3.7.老年代內存統計:jstat -gcoldcapacity 66570

localhost:~ gaoxinfu$ jstat -gcoldcapacity 66570
   OGCMN       OGCMX        OGC         OC       YGC   FGC    FGCT     GCT   
    68608.0    136704.0     68608.0     68608.0     8     1    0.050    0.115
localhost:~ gaoxinfu$ 

OGCMN：老年代最小容量
OGCMX：老年代最大容量
OGC：當前老年代大小
OC：老年代大小
YGC：年輕代垃圾回收次數
FGC：老年代垃圾回收次數
FGCT：老年代垃圾回收消耗時間
GCT：垃圾回收消耗總時間

3.8.JDK8 下 元數據空間統計:

localhost:~ gaoxinfu$ jstat -gcmetacapacity 66570
   MCMN       MCMX        MC       CCSMN      CCSMX       CCSC     YGC   FGC    FGCT     GCT   
       0.0  1079296.0    34688.0        0.0  1048576.0     4480.0     8     1    0.050    0.115
localhost:~ gaoxinfu$ 

MCMN:最小元數據容量
MCMX：最大元數據容量
MC：當前元數據空間大小
CCSMN：最小壓縮類空間大小
CCSMX：最大壓縮類空間大小
CCSC：當前壓縮類空間大小
YGC：年輕代垃圾回收次數
FGC：老年代垃圾回收次數
FGCT：老年代垃圾回收消耗時間
GCT：垃圾回收消耗總時間

4.jstack ：查看線程的堆棧信息

4.1.概念

Prints Java thread stack traces for a Java process, core file, or remote debug server. This command is experimental and unsupported.

打印當前應用進程|文件|遠程調試的服務的Java線程的棧信息情況

格式

jstack [pid]

4.2.jstack 66570

localhost:~ gaoxinfu$ jps 
72514 Jstat
63720 
66569 Launcher
66570 DemoJvmApplication
23726 Jps
72639 Jstat
localhost:~ gaoxinfu$ jstack 66570
2020-03-12 10:26:13
Full thread dump Java HotSpot(TM) 64-Bit Server VM (25.211-b12 mixed mode):

"Attach Listener" #33 daemon prio=9 os_prio=31 tid=0x00007fe3eefed000 nid=0x9c03 waiting on condition [0x0000000000000000]
   java.lang.Thread.State: RUNNABLE

"DestroyJavaVM" #32 prio=5 os_prio=31 tid=0x00007fe3eff71000 nid=0xe03 waiting on condition [0x0000000000000000]
   java.lang.Thread.State: RUNNABLE

"http-nio-8080-Acceptor" #30 daemon prio=5 os_prio=31 tid=0x00007fe3eff6f000 nid=0x6103 runnable [0x000070000cb4c000]
   java.lang.Thread.State: RUNNABLE
	at sun.nio.ch.ServerSocketChannelImpl.accept0(Native Method)
	at sun.nio.ch.ServerSocketChannelImpl.accept(ServerSocketChannelImpl.java:422)
	at sun.nio.ch.ServerSocketChannelImpl.accept(ServerSocketChannelImpl.java:250)
	- locked <0x00000007bbe10240> (a java.lang.Object)
	at org.apache.tomcat.util.net.NioEndpoint.serverSocketAccept(NioEndpoint.java:463)
	at org.apache.tomcat.util.net.NioEndpoint.serverSocketAccept(NioEndpoint.java:73)
	at org.apache.tomcat.util.net.Acceptor.run(Acceptor.java:95)
	at java.lang.Thread.run(Thread.java:748)

"http-nio-8080-ClientPoller" #29 daemon prio=5 os_prio=31 tid=0x00007fe3edff7000 nid=0x9e03 runnable [0x000070000ca49000]
   java.lang.Thread.State: RUNNABLE
	at sun.nio.ch.KQueueArrayWrapper.kevent0(Native Method)
	at sun.nio.ch.KQueueArrayWrapper.poll(KQueueArrayWrapper.java:198)
	at sun.nio.ch.KQueueSelectorImpl.doSelect(KQueueSelectorImpl.java:117)
	at sun.nio.ch.SelectorImpl.lockAndDoSelect(SelectorImpl.java:86)
	- locked <0x00000007bbf5dd10> (a sun.nio.ch.Util$3)
	- locked <0x00000007bbf5dd00> (a java.util.Collections$UnmodifiableSet)
	- locked <0x00000007bbf5dbe0> (a sun.nio.ch.KQueueSelectorImpl)
	at sun.nio.ch.SelectorImpl.select(SelectorImpl.java:97)
	at org.apache.tomcat.util.net.NioEndpoint$Poller.run(NioEndpoint.java:708)
	at java.lang.Thread.run(Thread.java:748)

"http-nio-8080-exec-10" #28 daemon prio=5 os_prio=31 tid=0x00007fe3edff2000 nid=0x6003 waiting on condition [0x000070000c946000]
   java.lang.Thread.State: WAITING (parking)
	at sun.misc.Unsafe.park(Native Method)
	- parking to wait for  <0x00000007bbec15b8> (a java.util.concurrent.locks.AbstractQueuedSynchronizer$ConditionObject)
	at java.util.concurrent.locks.LockSupport.park(LockSupport.java:175)
	at java.util.concurrent.locks.AbstractQueuedSynchronizer$ConditionObject.await(AbstractQueuedSynchronizer.java:2039)
	at java.util.concurrent.LinkedBlockingQueue.take(LinkedBlockingQueue.java:442)
	at org.apache.tomcat.util.threads.TaskQueue.take(TaskQueue.java:107)
	at org.apache.tomcat.util.threads.TaskQueue.take(TaskQueue.java:33)
	at java.util.concurrent.ThreadPoolExecutor.getTask(ThreadPoolExecutor.java:1074)
	at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1134)
	at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
	at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)
	at java.lang.Thread.run(Thread.java:748)

"http-nio-8080-exec-9" #27 daemon prio=5 os_prio=31 tid=0x00007fe3eefee800 nid=0xa103 waiting on condition [0x000070000c843000]
   java.lang.Thread.State: WAITING (parking)
	at sun.misc.Unsafe.park(Native Method)
	- parking to wait for  <0x00000007bbec15b8> (a java.util.concurrent.locks.AbstractQueuedSynchronizer$ConditionObject)
	at java.util.concurrent.locks.LockSupport.park(LockSupport.java:175)
	at java.util.concurrent.locks.AbstractQueuedSynchronizer$ConditionObject.await(AbstractQueuedSynchronizer.java:2039)
	at java.util.concurrent.LinkedBlockingQueue.take(LinkedBlockingQueue.java:442)
	at org.apache.tomcat.util.threads.TaskQueue.take(TaskQueue.java:107)
	at org.apache.tomcat.util.threads.TaskQueue.take(TaskQueue.java:33)
	at java.util.concurrent.ThreadPoolExecutor.getTask(ThreadPoolExecutor.java:1074)
	at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1134)
	at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
	at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)
	at java.lang.Thread.run(Thread.java:748)

"http-nio-8080-exec-8" #26 daemon prio=5 os_prio=31 tid=0x00007fe3ecfab000 nid=0x5e03 waiting on condition [0x000070000c740000]
   java.lang.Thread.State: WAITING (parking)
	at sun.misc.Unsafe.park(Native Method)
	- parking to wait for  <0x00000007bbec15b8> (a java.util.concurrent.locks.AbstractQueuedSynchronizer$ConditionObject)
	at java.util.concurrent.locks.LockSupport.park(LockSupport.java:175)
	at java.util.concurrent.locks.AbstractQueuedSynchronizer$ConditionObject.await(AbstractQueuedSynchronizer.java:2039)
	at java.util.concurrent.LinkedBlockingQueue.take(LinkedBlockingQueue.java:442)
	at org.apache.tomcat.util.threads.TaskQueue.take(TaskQueue.java:107)
	at org.apache.tomcat.util.threads.TaskQueue.take(TaskQueue.java:33)
	at java.util.concurrent.ThreadPoolExecutor.getTask(ThreadPoolExecutor.java:1074)
	at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1134)
	at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
	at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)
	at java.lang.Thread.run(Thread.java:748)

"http-nio-8080-exec-7" #25 daemon prio=5 os_prio=31 tid=0x00007fe3ecdac000 nid=0x5c03 waiting on condition [0x000070000c63d000]
   java.lang.Thread.State: WAITING (parking)
	at sun.misc.Unsafe.park(Native Method)
	- parking to wait for  <0x00000007bbec15b8> (a java.util.concurrent.locks.AbstractQueuedSynchronizer$ConditionObject)
	at java.util.concurrent.locks.LockSupport.park(LockSupport.java:175)
	at java.util.concurrent.locks.AbstractQueuedSynchronizer$ConditionObject.await(AbstractQueuedSynchronizer.java:2039)
	at java.util.concurrent.LinkedBlockingQueue.take(LinkedBlockingQueue.java:442)
	at org.apache.tomcat.util.threads.TaskQueue.take(TaskQueue.java:107)
	at org.apache.tomcat.util.threads.TaskQueue.take(TaskQueue.java:33)
	at java.util.concurrent.ThreadPoolExecutor.getTask(ThreadPoolExecutor.java:1074)
	at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1134)
	at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
	at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)
	at java.lang.Thread.run(Thread.java:748)

"http-nio-8080-exec-6" #24 daemon prio=5 os_prio=31 tid=0x00007fe3eefee000 nid=0xa303 waiting on condition [0x000070000c53a000]
   java.lang.Thread.State: WAITING (parking)
	at sun.misc.Unsafe.park(Native Method)
	- parking to wait for  <0x00000007bbec15b8> (a java.util.concurrent.locks.AbstractQueuedSynchronizer$ConditionObject)
	at java.util.concurrent.locks.LockSupport.park(LockSupport.java:175)
	at java.util.concurrent.locks.AbstractQueuedSynchronizer$ConditionObject.await(AbstractQueuedSynchronizer.java:2039)
	at java.util.concurrent.LinkedBlockingQueue.take(LinkedBlockingQueue.java:442)
	at org.apache.tomcat.util.threads.TaskQueue.take(TaskQueue.java:107)
	at org.apache.tomcat.util.threads.TaskQueue.take(TaskQueue.java:33)
	at java.util.concurrent.ThreadPoolExecutor.getTask(ThreadPoolExecutor.java:1074)
	at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1134)
	at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
	at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)
	at java.lang.Thread.run(Thread.java:748)

"http-nio-8080-exec-5" #23 daemon prio=5 os_prio=31 tid=0x00007fe3ecdab000 nid=0x5b03 waiting on condition [0x000070000c437000]
   java.lang.Thread.State: WAITING (parking)
	at sun.misc.Unsafe.park(Native Method)
	- parking to wait for  <0x00000007bbec15b8> (a java.util.concurrent.locks.AbstractQueuedSynchronizer$ConditionObject)
	at java.util.concurrent.locks.LockSupport.park(LockSupport.java:175)
	at java.util.concurrent.locks.AbstractQueuedSynchronizer$ConditionObject.await(AbstractQueuedSynchronizer.java:2039)
	at java.util.concurrent.LinkedBlockingQueue.take(LinkedBlockingQueue.java:442)
	at org.apache.tomcat.util.threads.TaskQueue.take(TaskQueue.java:107)
	at org.apache.tomcat.util.threads.TaskQueue.take(TaskQueue.java:33)
	at java.util.concurrent.ThreadPoolExecutor.getTask(ThreadPoolExecutor.java:1074)
	at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1134)
	at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
	at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)
	at java.lang.Thread.run(Thread.java:748)

"http-nio-8080-exec-4" #22 daemon prio=5 os_prio=31 tid=0x00007fe3ece7e800 nid=0x5a03 waiting on condition [0x000070000c334000]
   java.lang.Thread.State: WAITING (parking)
	at sun.misc.Unsafe.park(Native Method)
	- parking to wait for  <0x00000007bbec15b8> (a java.util.concurrent.locks.AbstractQueuedSynchronizer$ConditionObject)
	at java.util.concurrent.locks.LockSupport.park(LockSupport.java:175)
	at java.util.concurrent.locks.AbstractQueuedSynchronizer$ConditionObject.await(AbstractQueuedSynchronizer.java:2039)
	at java.util.concurrent.LinkedBlockingQueue.take(LinkedBlockingQueue.java:442)
	at org.apache.tomcat.util.threads.TaskQueue.take(TaskQueue.java:107)
	at org.apache.tomcat.util.threads.TaskQueue.take(TaskQueue.java:33)
	at java.util.concurrent.ThreadPoolExecutor.getTask(ThreadPoolExecutor.java:1074)
	at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1134)
	at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
	at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)
	at java.lang.Thread.run(Thread.java:748)

"http-nio-8080-exec-3" #21 daemon prio=5 os_prio=31 tid=0x00007fe3efe26800 nid=0xa603 waiting on condition [0x000070000c231000]
   java.lang.Thread.State: WAITING (parking)
	at sun.misc.Unsafe.park(Native Method)
	- parking to wait for  <0x00000007bbec15b8> (a java.util.concurrent.locks.AbstractQueuedSynchronizer$ConditionObject)
	at java.util.concurrent.locks.LockSupport.park(LockSupport.java:175)
	at java.util.concurrent.locks.AbstractQueuedSynchronizer$ConditionObject.await(AbstractQueuedSynchronizer.java:2039)
	at java.util.concurrent.LinkedBlockingQueue.take(LinkedBlockingQueue.java:442)
	at org.apache.tomcat.util.threads.TaskQueue.take(TaskQueue.java:107)
	at org.apache.tomcat.util.threads.TaskQueue.take(TaskQueue.java:33)
	at java.util.concurrent.ThreadPoolExecutor.getTask(ThreadPoolExecutor.java:1074)
	at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1134)
	at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
	at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)
	at java.lang.Thread.run(Thread.java:748)

"http-nio-8080-exec-2" #20 daemon prio=5 os_prio=31 tid=0x00007fe3ecff7000 nid=0xa803 waiting on condition [0x000070000c12e000]
   java.lang.Thread.State: WAITING (parking)
	at sun.misc.Unsafe.park(Native Method)
	- parking to wait for  <0x00000007bbec15b8> (a java.util.concurrent.locks.AbstractQueuedSynchronizer$ConditionObject)
	at java.util.concurrent.locks.LockSupport.park(LockSupport.java:175)
	at java.util.concurrent.locks.AbstractQueuedSynchronizer$ConditionObject.await(AbstractQueuedSynchronizer.java:2039)
	at java.util.concurrent.LinkedBlockingQueue.take(LinkedBlockingQueue.java:442)
	at org.apache.tomcat.util.threads.TaskQueue.take(TaskQueue.java:107)
	at org.apache.tomcat.util.threads.TaskQueue.take(TaskQueue.java:33)
	at java.util.concurrent.ThreadPoolExecutor.getTask(ThreadPoolExecutor.java:1074)
	at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1134)
	at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
	at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)
	at java.lang.Thread.run(Thread.java:748)

"http-nio-8080-exec-1" #19 daemon prio=5 os_prio=31 tid=0x00007fe3eef4b000 nid=0x5703 waiting on condition [0x000070000c02b000]
   java.lang.Thread.State: WAITING (parking)
	at sun.misc.Unsafe.park(Native Method)
	- parking to wait for  <0x00000007bbec15b8> (a java.util.concurrent.locks.AbstractQueuedSynchronizer$ConditionObject)
	at java.util.concurrent.locks.LockSupport.park(LockSupport.java:175)
	at java.util.concurrent.locks.AbstractQueuedSynchronizer$ConditionObject.await(AbstractQueuedSynchronizer.java:2039)
	at java.util.concurrent.LinkedBlockingQueue.take(LinkedBlockingQueue.java:442)
	at org.apache.tomcat.util.threads.TaskQueue.take(TaskQueue.java:107)
	at org.apache.tomcat.util.threads.TaskQueue.take(TaskQueue.java:33)
	at java.util.concurrent.ThreadPoolExecutor.getTask(ThreadPoolExecutor.java:1074)
	at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1134)
	at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
	at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)
	at java.lang.Thread.run(Thread.java:748)

"http-nio-8080-BlockPoller" #18 daemon prio=5 os_prio=31 tid=0x00007fe3ee960800 nid=0x4e0b runnable [0x000070000bf28000]
   java.lang.Thread.State: RUNNABLE
	at sun.nio.ch.KQueueArrayWrapper.kevent0(Native Method)
	at sun.nio.ch.KQueueArrayWrapper.poll(KQueueArrayWrapper.java:198)
	at sun.nio.ch.KQueueSelectorImpl.doSelect(KQueueSelectorImpl.java:117)
	at sun.nio.ch.SelectorImpl.lockAndDoSelect(SelectorImpl.java:86)
	- locked <0x00000007bbe3a3a8> (a sun.nio.ch.Util$3)
	- locked <0x00000007bbe39300> (a java.util.Collections$UnmodifiableSet)
	- locked <0x00000007bbe39178> (a sun.nio.ch.KQueueSelectorImpl)
	at sun.nio.ch.SelectorImpl.select(SelectorImpl.java:97)
	at org.apache.tomcat.util.net.NioBlockingSelector$BlockPoller.run(NioBlockingSelector.java:313)

"container-0" #17 prio=5 os_prio=31 tid=0x00007fe3eddd0000 nid=0x5503 waiting on condition [0x000070000be25000]
   java.lang.Thread.State: TIMED_WAITING (sleeping)
	at java.lang.Thread.sleep(Native Method)
	at org.apache.catalina.core.StandardServer.await(StandardServer.java:570)
	at org.springframework.boot.web.embedded.tomcat.TomcatWebServer$1.run(TomcatWebServer.java:179)

"Catalina-utility-2" #16 prio=1 os_prio=31 tid=0x00007fe3eaecd000 nid=0x4207 waiting on condition [0x000070000bd22000]
   java.lang.Thread.State: WAITING (parking)
	at sun.misc.Unsafe.park(Native Method)
	- parking to wait for  <0x00000007bf8819b8> (a java.util.concurrent.locks.AbstractQueuedSynchronizer$ConditionObject)
	at java.util.concurrent.locks.LockSupport.park(LockSupport.java:175)
	at java.util.concurrent.locks.AbstractQueuedSynchronizer$ConditionObject.await(AbstractQueuedSynchronizer.java:2039)
	at java.util.concurrent.ScheduledThreadPoolExecutor$DelayedWorkQueue.take(ScheduledThreadPoolExecutor.java:1088)
	at java.util.concurrent.ScheduledThreadPoolExecutor$DelayedWorkQueue.take(ScheduledThreadPoolExecutor.java:809)
	at java.util.concurrent.ThreadPoolExecutor.getTask(ThreadPoolExecutor.java:1074)
	at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1134)
	at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
	at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)
	at java.lang.Thread.run(Thread.java:748)

"Catalina-utility-1" #15 prio=1 os_prio=31 tid=0x00007fe3ea755000 nid=0x4407 waiting on condition [0x000070000bc1f000]
   java.lang.Thread.State: TIMED_WAITING (parking)
	at sun.misc.Unsafe.park(Native Method)
	- parking to wait for  <0x00000007bf8819b8> (a java.util.concurrent.locks.AbstractQueuedSynchronizer$ConditionObject)
	at java.util.concurrent.locks.LockSupport.parkNanos(LockSupport.java:215)
	at java.util.concurrent.locks.AbstractQueuedSynchronizer$ConditionObject.awaitNanos(AbstractQueuedSynchronizer.java:2078)
	at java.util.concurrent.ScheduledThreadPoolExecutor$DelayedWorkQueue.take(ScheduledThreadPoolExecutor.java:1093)
	at java.util.concurrent.ScheduledThreadPoolExecutor$DelayedWorkQueue.take(ScheduledThreadPoolExecutor.java:809)
	at java.util.concurrent.ThreadPoolExecutor.getTask(ThreadPoolExecutor.java:1074)
	at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1134)
	at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
	at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)
	at java.lang.Thread.run(Thread.java:748)

"Service Thread" #11 daemon prio=9 os_prio=31 tid=0x00007fe3eb095800 nid=0x4603 runnable [0x0000000000000000]
   java.lang.Thread.State: RUNNABLE

"C1 CompilerThread2" #10 daemon prio=9 os_prio=31 tid=0x00007fe3ea8bd800 nid=0x4703 waiting on condition [0x0000000000000000]
   java.lang.Thread.State: RUNNABLE

"C2 CompilerThread1" #9 daemon prio=9 os_prio=31 tid=0x00007fe3ea8bc800 nid=0x4803 waiting on condition [0x0000000000000000]
   java.lang.Thread.State: RUNNABLE

"C2 CompilerThread0" #8 daemon prio=9 os_prio=31 tid=0x00007fe3ea8bc000 nid=0x3b03 waiting on condition [0x0000000000000000]
   java.lang.Thread.State: RUNNABLE

"JDWP Command Reader" #7 daemon prio=10 os_prio=31 tid=0x00007fe3eb83e000 nid=0x4903 runnable [0x0000000000000000]
   java.lang.Thread.State: RUNNABLE

"JDWP Event Helper Thread" #6 daemon prio=10 os_prio=31 tid=0x00007fe3ea01d800 nid=0x3803 runnable [0x0000000000000000]
   java.lang.Thread.State: RUNNABLE

"JDWP Transport Listener: dt_socket" #5 daemon prio=10 os_prio=31 tid=0x00007fe3ea01c800 nid=0x3707 runnable [0x0000000000000000]
   java.lang.Thread.State: RUNNABLE

"Signal Dispatcher" #4 daemon prio=9 os_prio=31 tid=0x00007fe3ea00c800 nid=0x4b03 runnable [0x0000000000000000]
   java.lang.Thread.State: RUNNABLE

"Finalizer" #3 daemon prio=8 os_prio=31 tid=0x00007fe3ea003000 nid=0x2e03 in Object.wait() [0x000070000b0fb000]
   java.lang.Thread.State: WAITING (on object monitor)
	at java.lang.Object.wait(Native Method)
	- waiting on <0x00000007b3cc01c0> (a java.lang.ref.ReferenceQueue$Lock)
	at java.lang.ref.ReferenceQueue.remove(ReferenceQueue.java:144)
	- locked <0x00000007b3cc01c0> (a java.lang.ref.ReferenceQueue$Lock)
	at java.lang.ref.ReferenceQueue.remove(ReferenceQueue.java:165)
	at java.lang.ref.Finalizer$FinalizerThread.run(Finalizer.java:216)

"Reference Handler" #2 daemon prio=10 os_prio=31 tid=0x00007fe3ea816000 nid=0x5403 in Object.wait() [0x000070000aff8000]
   java.lang.Thread.State: WAITING (on object monitor)
	at java.lang.Object.wait(Native Method)
	- waiting on <0x00000007b3cd0b68> (a java.lang.ref.Reference$Lock)
	at java.lang.Object.wait(Object.java:502)
	at java.lang.ref.Reference.tryHandlePending(Reference.java:191)
	- locked <0x00000007b3cd0b68> (a java.lang.ref.Reference$Lock)
	at java.lang.ref.Reference$ReferenceHandler.run(Reference.java:153)

"VM Thread" os_prio=31 tid=0x00007fe3ea002000 nid=0x2c03 runnable 

"GC task thread#0 (ParallelGC)" os_prio=31 tid=0x00007fe3eb004800 nid=0x2407 runnable 

"GC task thread#1 (ParallelGC)" os_prio=31 tid=0x00007fe3ea803000 nid=0x2303 runnable 

"GC task thread#2 (ParallelGC)" os_prio=31 tid=0x00007fe3eb80d000 nid=0x2103 runnable 

"GC task thread#3 (ParallelGC)" os_prio=31 tid=0x00007fe3eb808800 nid=0x2a03 runnable 

"VM Periodic Task Thread" os_prio=31 tid=0x00007fe3ea0f0000 nid=0x4503 waiting on condition 

JNI global references: 16314

localhost:~ gaoxinfu$ 

4.3.適用場景

1.線程死鎖等問題發生時，方便排查;

4.4.案例說明

4.4.1.代碼

代碼地址
https://gitee.com/gaoxinfu_admin/demo-jdk/blob/master/demo-jvm/src/main/java/com/gaoxinfu/demo/jvm/jstack/DeadLockDemo.java

package com.gaoxinfu.demo.jvm.jstack;

//運行主類
public class DeadLockDemo
{
    public static void main(String[] args)
    {
        DeadLock d1=new DeadLock(true);
        DeadLock d2=new DeadLock(false);
        Thread t1=new Thread(d1);
        Thread t2=new Thread(d2);
        t1.start();
        t2.start();
    }
}
//定義鎖對象
class MyLock{
    public static Object obj1=new Object();
    public static Object obj2=new Object();
}
//死鎖代碼
class DeadLock implements Runnable{
    private boolean flag;
    DeadLock(boolean flag){
        this.flag=flag;
    }
    public void run() {
        if(flag) {
            while(true) {
                synchronized(MyLock.obj1) {
                    System.out.println(Thread.currentThread().getName()+"----if獲得obj1鎖");
                    synchronized(MyLock.obj2) {
                        System.out.println(Thread.currentThread().getName()+"----if獲得obj2鎖");
                    }
                }
            }
        }
        else {
            while(true){
                synchronized(MyLock.obj2) {
                    System.out.println(Thread.currentThread().getName()+"----否則獲得obj2鎖");
                    synchronized(MyLock.obj1) {
                        System.out.println(Thread.currentThread().getName()+"----否則獲得obj1鎖");

                    }
                }
            }
        }
    }
}

4.4.2.運行DeadLockDemo的main方法

1.從上面，我們看到線程0和線程1相互之間已經鎖定，無法獲得鎖，導致無法繼續往下進行

4.4.3.通過jstack查看具體的問題

localhost:~ gaoxinfu$ jps
29472 Launcher
72514 Jstat
29475 DeadLockDemo
28931 RemoteMavenServer
63720 
72639 Jstat
29567 Jps
localhost:~ gaoxinfu$ jstack 29475
2020-03-12 10:47:51
Full thread dump Java HotSpot(TM) 64-Bit Server VM (25.211-b12 mixed mode):

"Attach Listener" #13 daemon prio=9 os_prio=31 tid=0x00007fec318d6800 nid=0x3c03 waiting on condition [0x0000000000000000]
   java.lang.Thread.State: RUNNABLE

"DestroyJavaVM" #12 prio=5 os_prio=31 tid=0x00007fec32152000 nid=0xe03 waiting on condition [0x0000000000000000]
   java.lang.Thread.State: RUNNABLE

"Thread-1" #11 prio=5 os_prio=31 tid=0x00007fec30908000 nid=0x4003 waiting for monitor entry [0x0000700003fa4000]
   java.lang.Thread.State: BLOCKED (on object monitor)
	at com.gaoxinfu.demo.jvm.jstack.DeadLock.run(DeadLockDemo.java:43)
	- waiting to lock <0x00000007958204a8> (a java.lang.Object)
	- locked <0x00000007958204b8> (a java.lang.Object)
	at java.lang.Thread.run(Thread.java:748)

"Thread-0" #10 prio=5 os_prio=31 tid=0x00007fec32151800 nid=0x3903 waiting for monitor entry [0x0000700003ea1000]
   java.lang.Thread.State: BLOCKED (on object monitor)
	at com.gaoxinfu.demo.jvm.jstack.DeadLock.run(DeadLockDemo.java:33)
	- waiting to lock <0x00000007958204b8> (a java.lang.Object)
	- locked <0x00000007958204a8> (a java.lang.Object)
	at java.lang.Thread.run(Thread.java:748)

"Service Thread" #9 daemon prio=9 os_prio=31 tid=0x00007fec310b4000 nid=0x3703 runnable [0x0000000000000000]
   java.lang.Thread.State: RUNNABLE

"C1 CompilerThread2" #8 daemon prio=9 os_prio=31 tid=0x00007fec3088b800 nid=0x3503 waiting on condition [0x0000000000000000]
   java.lang.Thread.State: RUNNABLE

"C2 CompilerThread1" #7 daemon prio=9 os_prio=31 tid=0x00007fec30878800 nid=0x4403 waiting on condition [0x0000000000000000]
   java.lang.Thread.State: RUNNABLE

"C2 CompilerThread0" #6 daemon prio=9 os_prio=31 tid=0x00007fec30877800 nid=0x3403 waiting on condition [0x0000000000000000]
   java.lang.Thread.State: RUNNABLE

"Monitor Ctrl-Break" #5 daemon prio=5 os_prio=31 tid=0x00007fec31805000 nid=0x4703 runnable [0x000070000388f000]
   java.lang.Thread.State: RUNNABLE
	at java.net.SocketInputStream.socketRead0(Native Method)
	at java.net.SocketInputStream.socketRead(SocketInputStream.java:116)
	at java.net.SocketInputStream.read(SocketInputStream.java:171)
	at java.net.SocketInputStream.read(SocketInputStream.java:141)
	at sun.nio.cs.StreamDecoder.readBytes(StreamDecoder.java:284)
	at sun.nio.cs.StreamDecoder.implRead(StreamDecoder.java:326)
	at sun.nio.cs.StreamDecoder.read(StreamDecoder.java:178)
	- locked <0x00000007957b2eb0> (a java.io.InputStreamReader)
	at java.io.InputStreamReader.read(InputStreamReader.java:184)
	at java.io.BufferedReader.fill(BufferedReader.java:161)
	at java.io.BufferedReader.readLine(BufferedReader.java:324)
	- locked <0x00000007957b2eb0> (a java.io.InputStreamReader)
	at java.io.BufferedReader.readLine(BufferedReader.java:389)
	at com.intellij.rt.execution.application.AppMainV2$1.run(AppMainV2.java:64)

"Signal Dispatcher" #4 daemon prio=9 os_prio=31 tid=0x00007fec31023000 nid=0x4803 runnable [0x0000000000000000]
   java.lang.Thread.State: RUNNABLE

"Finalizer" #3 daemon prio=8 os_prio=31 tid=0x00007fec3101b800 nid=0x2c03 in Object.wait() [0x0000700003583000]
   java.lang.Thread.State: WAITING (on object monitor)
	at java.lang.Object.wait(Native Method)
	- waiting on <0x0000000795588ed0> (a java.lang.ref.ReferenceQueue$Lock)
	at java.lang.ref.ReferenceQueue.remove(ReferenceQueue.java:144)
	- locked <0x0000000795588ed0> (a java.lang.ref.ReferenceQueue$Lock)
	at java.lang.ref.ReferenceQueue.remove(ReferenceQueue.java:165)
	at java.lang.ref.Finalizer$FinalizerThread.run(Finalizer.java:216)

"Reference Handler" #2 daemon prio=10 os_prio=31 tid=0x00007fec3101b000 nid=0x5203 in Object.wait() [0x0000700003480000]
   java.lang.Thread.State: WAITING (on object monitor)
	at java.lang.Object.wait(Native Method)
	- waiting on <0x0000000795586bf8> (a java.lang.ref.Reference$Lock)
	at java.lang.Object.wait(Object.java:502)
	at java.lang.ref.Reference.tryHandlePending(Reference.java:191)
	- locked <0x0000000795586bf8> (a java.lang.ref.Reference$Lock)
	at java.lang.ref.Reference$ReferenceHandler.run(Reference.java:153)

"VM Thread" os_prio=31 tid=0x00007fec31018000 nid=0x2b03 runnable 

"GC task thread#0 (ParallelGC)" os_prio=31 tid=0x00007fec31809800 nid=0x2007 runnable 

"GC task thread#1 (ParallelGC)" os_prio=31 tid=0x00007fec31006000 nid=0x2403 runnable 

"GC task thread#2 (ParallelGC)" os_prio=31 tid=0x00007fec31006800 nid=0x2303 runnable 

"GC task thread#3 (ParallelGC)" os_prio=31 tid=0x00007fec32000800 nid=0x2a03 runnable 

"VM Periodic Task Thread" os_prio=31 tid=0x00007fec31024000 nid=0x4203 waiting on condition 

JNI global references: 15


Found one Java-level deadlock:
=============================
"Thread-1":
  waiting to lock monitor 0x00007fec320283e8 (object 0x00000007958204a8, a java.lang.Object),
  which is held by "Thread-0"
"Thread-0":
  waiting to lock monitor 0x00007fec32025cb8 (object 0x00000007958204b8, a java.lang.Object),
  which is held by "Thread-1"

Java stack information for the threads listed above:
===================================================
"Thread-1":
	at com.gaoxinfu.demo.jvm.jstack.DeadLock.run(DeadLockDemo.java:43)
	- waiting to lock <0x00000007958204a8> (a java.lang.Object)
	- locked <0x00000007958204b8> (a java.lang.Object)
	at java.lang.Thread.run(Thread.java:748)
"Thread-0":
	at com.gaoxinfu.demo.jvm.jstack.DeadLock.run(DeadLockDemo.java:33)
	- waiting to lock <0x00000007958204b8> (a java.lang.Object)
	- locked <0x00000007958204a8> (a java.lang.Object)
	at java.lang.Thread.run(Thread.java:748)

Found 1 deadlock.

localhost:~ gaoxinfu$ 

1.從上面我們知道發現了一個死鎖；
2.線程1在等待獲取鎖0x00000007958204a8，但是0x00000007958204a8被線程0已經鎖定
  線程0在等待獲取鎖0x00000007958204b8，但是0x00000007958204b8被線程1已經鎖定
這樣接下來，我們通過上面的分析，可以定位的代碼的問題，從而去優化處理;
純粹的在通過業務代碼code去分析是不太好發現問題的；

5.jmap 查看堆內存的相關信息

5.1.查看指定進程的堆內存相關信息設置: jmap -heap 90844

5.1.1.格式： jmap -heap ${pid}

5.1.2.異常： Can’t attach symbolicator to the process

localhost:libexec gaoxinfu$ java -version
java version "1.8.0_211"
Java(TM) SE Runtime Environment (build 1.8.0_211-b12)
Java HotSpot(TM) 64-Bit Server VM (build 25.211-b12, mixed mode)
localhost:libexec gaoxinfu$ jps
72514 Jstat
63720 
90843 Launcher
90923 Jps
90844 DemoJvmApplication
72639 Jstat
localhost:libexec gaoxinfu$ jmap -heap 90844
Attaching to process ID 90844, please wait...
Error attaching to process: sun.jvm.hotspot.debugger.DebuggerException: Can't attach symbolicator to the process
sun.jvm.hotspot.debugger.DebuggerException: sun.jvm.hotspot.debugger.DebuggerException: Can't attach symbolicator to the process
	at sun.jvm.hotspot.debugger.bsd.BsdDebuggerLocal$BsdDebuggerLocalWorkerThread.execute(BsdDebuggerLocal.java:169)
	at sun.jvm.hotspot.debugger.bsd.BsdDebuggerLocal.attach(BsdDebuggerLocal.java:287)
	at sun.jvm.hotspot.HotSpotAgent.attachDebugger(HotSpotAgent.java:671)
	at sun.jvm.hotspot.HotSpotAgent.setupDebuggerDarwin(HotSpotAgent.java:659)
	at sun.jvm.hotspot.HotSpotAgent.setupDebugger(HotSpotAgent.java:341)
	at sun.jvm.hotspot.HotSpotAgent.go(HotSpotAgent.java:304)
	at sun.jvm.hotspot.HotSpotAgent.attach(HotSpotAgent.java:140)
	at sun.jvm.hotspot.tools.Tool.start(Tool.java:185)
	at sun.jvm.hotspot.tools.Tool.execute(Tool.java:118)
	at sun.jvm.hotspot.tools.HeapSummary.main(HeapSummary.java:49)
	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
	at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
	at java.lang.reflect.Method.invoke(Method.java:498)
	at sun.tools.jmap.JMap.runTool(JMap.java:201)
	at sun.tools.jmap.JMap.main(JMap.java:130)
Caused by: sun.jvm.hotspot.debugger.DebuggerException: Can't attach symbolicator to the process
	at sun.jvm.hotspot.debugger.bsd.BsdDebuggerLocal.attach0(Native Method)
	at sun.jvm.hotspot.debugger.bsd.BsdDebuggerLocal.access$100(BsdDebuggerLocal.java:65)
	at sun.jvm.hotspot.debugger.bsd.BsdDebuggerLocal$1AttachTask.doit(BsdDebuggerLocal.java:278)
	at sun.jvm.hotspot.debugger.bsd.BsdDebuggerLocal$BsdDebuggerLocalWorkerThread.run(BsdDebuggerLocal.java:144)

localhost:libexec gaoxinfu$ 

5.1.2.正常的 TODO

5.1.3.命令行格式：將堆內存輸出到文件中

5.1.3.1.格式：jmap -dump:format=b,file=heap.hprof 93325

jmap -dump:format=b,file=${文件名} ${進程ID} 

jmap -dump:format=b 固定格式

5.1.3.2.演示

localhost:libexec gaoxinfu$ jps
72514 Jstat
93445 Jps
63720 
93325 DemoJvmApplication
93324 Launcher
72639 Jstat
localhost:libexec gaoxinfu$ jmap -dump:format=b,file=heap.hprof 93325
Dumping heap to /usr/libexec/heap.hprof ...
Operation not permitted
localhost:libexec gaoxinfu$ pwd
/usr/libexec
localhost:libexec gaoxinfu$ cd ~
localhost:~ gaoxinfu$ jmap -dump:format=b,file=heap.hprof 93325
Dumping heap to /Users/gaoxinfu/heap.hprof ...
Heap dump file created
localhost:~ gaoxinfu$ pwd
/Users/gaoxinfu
localhost:~ gaoxinfu$ 

關於上面生成的heap.hprof文件查看，我們後面通過工具去查看，暫時不做介紹

5.1.3.開發工具方式(Idea)：發生內存溢出的時候，將堆內存輸出到文件中

5.1.3.1.設置參數 -XX:+HeapDumpOnOutOfMemoryError -XX:HeapDumpPath=heap.hprof

**-XX:+HeapDumpOnOutOfMemoryError -XX:HeapDumpPath=heap.hprof **

-XX:+PrintFlagsFinal -Xms1M -Xmx10M -XX:+HeapDumpOnOutOfMemoryError -XX:HeapDumpPath=heap.hprof 

-XX:+PrintFlagsFinal 啓動打印全部jvm參數
-Xms1M -Xmx10M ：堆內存設置最小1M，最大10M
-XX:+HeapDumpOnOutOfMemoryError 開啓堆內存溢出的時候做某些操作
-XX:HeapDumpPath=heap.hprof 溢出時，輸出到文件中

5.1.3.2.請求模擬內存溢出

http://localhost:8080/heap

5.1.3.3.文件生成成功