1、JVM的參數(shù)類型
1.1 標準參數(shù)：在各jdk版本中較穩(wěn)定
-help
-server -client
-version -showversion
-cp -classpath
1.2 X參數(shù)
1.2.1非標準化參數(shù)
1.2.2 -Xint：完全解釋執(zhí)行
調(diào)整為完全解釋執(zhí)行編譯模式：
MacBook-Pro:dubbo-learn chuanzhou$ java -Xint -version
java version "1.8.0_161"
Java(TM) SE Runtime Environment (build 1.8.0_161-b12)
Java HotSpot(TM) 64-Bit Server VM (build 25.161-b12, interpreted mode)
1.2.3 -Xcomp：第一次使用就編譯成本地代碼
調(diào)整為編譯執(zhí)行編譯模式：
MacBook-Pro:dubbo-learn chuanzhou$ java -Xcomp -version
java version "1.8.0_161"
Java(TM) SE Runtime Environment (build 1.8.0_161-b12)
Java HotSpot(TM) 64-Bit Server VM (build 25.161-b12, compiled mode)
1.2.4 -Xmixed：混合模式，JVM自己來決定是否編譯成本地代碼
MacBook-Pro:~ chuanzhou$ java -version
java version "1.8.0_161"
Java(TM) SE Runtime Environment (build 1.8.0_161-b12)
Java HotSpot(TM) 64-Bit Server VM (build 25.161-b12, mixed mode)
最后一行的mixed mode表明JVM默認使用的編譯模式是混合模式
1.3 XX參數(shù)
使用最多的一種參數(shù)類型
1.3.1 Boolean類型
格式：-XX:[+/-] <name> 表示啟用或者禁用name屬性
比如：
-XX:+UseConcMarkSweepGC 表示啟用CMS垃圾回收器
-XX:+UseG1GC 表示啟用G1垃圾回收器
1.3.2 非Boolean類型
格式：-XX:<name> = <value> 表示name屬性的值為value
比如：
-XX:MaxGCPauseMillis=500 表示GC最大停頓時間是500毫秒
-XX:GCTimeRatio=19 表示...
1.3.3 -Xmx -Xms
雖然1以X開頭，但是不是X類型參數(shù)，而是XX類型的參數(shù)
- -Xmx等價于-XX:MaxHeapSize 表示最大堆內(nèi)存大小，可使用
jinfo -flag MaxHeapSize 進程id查看，如下：
[root@izwz93osmk5vi5qwqyscxaz bin]# ps -ef|grep java
root 9723 1 0 4月24 ? 04:28:59 /usr/program/jdk1.8.0_72/jre/bin/java -Djava.util.logging.config.file=/opt/tomcat/apache-tomcat-8.0.50/conf/logging.properties -Djava.util.logging.manager=org.apache.juli.ClassLoaderLogManager -Djdk.tls.ephemeralDHKeySize=2048 -Djava.protocol.handler.pkgs=org.apache.catalina.webresources -Dignore.endorsed.dirs= -classpath /opt/tomcat/apache-tomcat-8.0.50/bin/bootstrap.jar:/opt/tomcat/apache-tomcat-8.0.50/bin/tomcat-juli.jar -Dcatalina.base=/opt/tomcat/apache-tomcat-8.0.50 -Dcatalina.home=/opt/tomcat/apache-tomcat-8.0.50 -Djava.io.tmpdir=/opt/tomcat/apache-tomcat-8.0.50/temp org.apache.catalina.startup.Bootstrap start
root 20037 19984 0 20:53 pts/2 00:00:00 grep --color=auto java
[root@izwz93osmk5vi5qwqyscxaz bin]# ./jinfo -flag MaxHeapSize 9723
-XX:MaxHeapSize=482344960
[root@izwz93osmk5vi5qwqyscxaz bin]#
-Xms等價于-XX:InitalHeapSize 表示堆內(nèi)存初始大小
-Xss等價于-XX:InitalStackSize 表示線程棧的初始大小，可以使用
jinfo -flag ThreadStackSize 進程id查看，如下：
[root@izwz93osmk5vi5qwqyscxaz bin]# ps -ef
[root@izwz93osmk5vi5qwqyscxaz bin]# ps -ef|grep java
root 9723 1 0 4月24 ? 04:28:59 /usr/program/jdk1.8.0_72/jre/bin/java -Djava.util.logging.config.file=/opt/tomcat/apache-tomcat-8.0.50/conf/logging.properties -Djava.util.logging.manager=org.apache.juli.ClassLoaderLogManager -Djdk.tls.ephemeralDHKeySize=2048 -Djava.protocol.handler.pkgs=org.apache.catalina.webresources -Dignore.endorsed.dirs= -classpath /opt/tomcat/apache-tomcat-8.0.50/bin/bootstrap.jar:/opt/tomcat/apache-tomcat-8.0.50/bin/tomcat-juli.jar -Dcatalina.base=/opt/tomcat/apache-tomcat-8.0.50 -Dcatalina.home=/opt/tomcat/apache-tomcat-8.0.50 -Djava.io.tmpdir=/opt/tomcat/apache-tomcat-8.0.50/temp org.apache.catalina.startup.Bootstrap start
root 20037 19984 0 20:53 pts/2 00:00:00 grep --color=auto java
[root@izwz93osmk5vi5qwqyscxaz bin]# ./jinfo -flag MaxHeapSize 9723
-XX:MaxHeapSize=482344960
[root@izwz93osmk5vi5qwqyscxaz bin]# ./jinfo -flag ThreadStackSize 9723
-XX:ThreadStackSize=1024
[root@izwz93osmk5vi5qwqyscxaz bin]#
2、JVM運行時參數(shù)查看
-
-XX:+printFlagsInitial查看JVM運行時初始值 -
-XX:+printFlagsFinal查看JVM運行時最終值 -
-XX:+UnlockExperimentalVMOptions解鎖實驗參數(shù) -
-XX:+UnlockDiagnosticVMOptions解鎖診斷參數(shù) -
-XX:+PrintCommandLineFlags打印命令行參數(shù)
如查看JVM版本信息：java -XX:+PrintFlagsFinal -version > ~/version.txt
version.txt中部分參數(shù)：
[Global flags]
uintx AdaptiveSizeDecrementScaleFactor = 4 {product}
uintx AdaptiveSizeMajorGCDecayTimeScale = 10 {product}
uintx AdaptiveSizePausePolicy = 0 {product}
uintx AdaptiveSizePolicyCollectionCostMargin = 50 {product}
uintx AdaptiveSizePolicyInitializingSteps = 20 {product}
uintx AdaptiveSizePolicyOutputInterval = 0 {product}
uintx AdaptiveSizePolicyWeight = 10 {product}
uintx AdaptiveSizeThroughPutPolicy = 0 {product}
uintx AdaptiveTimeWeight = 25 {product}
bool AdjustConcurrency = false {product}
bool AggressiveOpts = false {product}
bool C1ProfileVirtualCalls = true {C1 product}
bool C1UpdateMethodData = true {C1 product}
intx CICompilerCount := 2 {product}
bool CICompilerCountPerCPU = true {product}
bool CITime = false {product}
bool CMSAbortSemantics = false {product}
uintx CMSAbortablePrecleanMinWorkPerIteration = 100 {product}
intx CMSAbortablePrecleanWaitMillis = 100 {manageable}
uintx CMSBitMapYieldQuantum = 10485760
注：=表示默認值，=:表示修改后的值
jps：查看Java進程
[root@izwz93osmk5vi5qwqyscxaz bin]# ./jps
20160 Jps
9723 Bootstrap
[root@izwz93osmk5vi5qwqyscxaz bin]# ./jps -l
20170 sun.tools.jps.Jps
9723 org.apache.catalina.startup.Bootstrap
[root@izwz93osmk5vi5qwqyscxaz bin]#
關于jps等命令的詳解，可參考此文檔https://docs.oracle.com/javase/8/docs/technotes/tools/unix/index.html
jinfo：查看指定Java進程運行時參數(shù)
如查看一個java進程id為9723的tomcat服務最大堆內(nèi)存大小
[root@izwz93osmk5vi5qwqyscxaz bin]# ps -ef|grep java
root 9723 1 0 4月24 ? 04:29:03 /usr/program/jdk1.8.0_72/jre/bin/java -Djava.util.logging.config.file=/opt/tomcat/apache-tomcat-8.0.50/conf/logging.properties -Djava.util.logging.manager=org.apache.juli.ClassLoaderLogManager -Djdk.tls.ephemeralDHKeySize=2048 -Djava.protocol.handler.pkgs=org.apache.catalina.webresources -Dignore.endorsed.dirs= -classpath /opt/tomcat/apache-tomcat-8.0.50/bin/bootstrap.jar:/opt/tomcat/apache-tomcat-8.0.50/bin/tomcat-juli.jar -Dcatalina.base=/opt/tomcat/apache-tomcat-8.0.50 -Dcatalina.home=/opt/tomcat/apache-tomcat-8.0.50 -Djava.io.tmpdir=/opt/tomcat/apache-tomcat-8.0.50/temp org.apache.catalina.startup.Bootstrap start
root 20187 20123 0 21:34 pts/2 00:00:00 grep --color=auto java
[root@izwz93osmk5vi5qwqyscxaz bin]# ./jinfo -flag MaxHeapSize 9723
-XX:MaxHeapSize=482344960
[root@izwz93osmk5vi5qwqyscxaz bin]#
查看一個進程的所有運行時參數(shù)：
[root@izwz93osmk5vi5qwqyscxaz bin]# ./jinfo -flags 9732
Attaching to process ID 9732, please wait...
Debugger attached successfully.
Server compiler detected.
JVM version is 25.72-b15
Non-default VM flags: -XX:CICompilerCount=2
-XX:InitialHeapSize=31457280 -XX:MaxHeapSize=482344960
-XX:MaxNewSize=160759808 -XX:MinHeapDeltaBytes=196608
-XX:NewSize=10485760 -XX:OldSize=20971520
-XX:+UseCompressedClassPointers -XX:+UseCompressedOops
Command line: -Djava.util.logging.config.file=/opt/tomcat/apache-tomcat-8.0.50/conf/logging.properties
-Djava.util.logging.manager=org.apache.juli.ClassLoaderLogManager -Djdk.tls.ephemeralDHKeySize=2048
-Djava.protocol.handler.pkgs=org.apache.catalina.webresources
-Dignore.endorsed.dirs= -Dcatalina.base=/opt/tomcat/apache-tomcat-8.0.50
-Dcatalina.home=/opt/tomcat/apache-tomcat-8.0.50
-Djava.io.tmpdir=/opt/tomcat/apache-tomcat-8.0.50/temp
[root@izwz93osmk5vi5qwqyscxaz bin]#
Non-default VM flags表示手動賦值過的參數(shù)，其中有些是tomcat設置的
Command line：與Non-default VM flags
查看垃圾回收器信息
MacBook-Pro:dubbo-learn chuanzhou$ jinfo -flag UseConcMarkSweepGc 29159
no such flag 'UseConcMarkSweepGc'
MacBook-Pro:dubbo-learn chuanzhou$ jinfo -flag UseG1Gc 29159
no such flag 'UseG1Gc'
MacBook-Pro:dubbo-learn chuanzhou$ jinfo -flag UseParallelGc 29159
no such flag 'UseParallelGc'
3、jstat查看虛擬機統(tǒng)計信息
3.1 類裝載
格式：jstat -class 進程id 每隔多少毫秒 一共輸出多少次
如：查看一個進程id為29159的java進程，每隔1s輸出，一共輸出10次
MacBook-Pro:dubbo-learn chuanzhou$ jstat -class 29159 1000 10
Loaded Bytes Unloaded Bytes Time
3204 6088.2 0 0.0 2.14
3204 6088.2 0 0.0 2.14
3204 6088.2 0 0.0 2.14
3204 6088.2 0 0.0 2.14
3204 6088.2 0 0.0 2.14
3204 6088.2 0 0.0 2.14
3204 6088.2 0 0.0 2.14
3204 6088.2 0 0.0 2.14
3204 6088.2 0 0.0 2.14
3204 6088.2 0 0.0 2.14
- Loaded：表示類加載的個數(shù)
- Bytes：表示類加載的大小，單位為kb
- UnLoaded：表示類卸載的個數(shù)
- Bytes：表示類卸載的大小，單位為kb
- Time：表示類加載和卸載的時間
3.2 垃圾收集
要查看一個java進程的垃圾收集器信息，可使用jstat -gc 進程id 每隔多少毫秒 一共輸出多少次
MacBook-Pro:dubbo-learn chuanzhou$ jstat -gc 29159 1000 3
S0C S1C S0U S1U EC EU OC OU MC MU CCSC CCSU YGC YGCT FGC FGCT GCT
5120.0 5120.0 4308.8 0.0 33280.0 17845.6 87552.0 88.0 18944.0 18304.7 2304.0 2144.9 2 0.014 0 0.000 0.014
5120.0 5120.0 4308.8 0.0 33280.0 17845.6 87552.0 88.0 18944.0 18304.7 2304.0 2144.9 2 0.014 0 0.000 0.014
5120.0 5120.0 4308.8 0.0 33280.0 17845.6 87552.0 88.0 18944.0 18304.7 2304.0 2144.9 2 0.014 0 0.000 0.014
S0C: Current survivor space 0 capacity (kB).表示survivor 0區(qū)的總大小
S1C: Current survivor space 1 capacity (kB).表示survivor 1區(qū)的總大小
S0U: Survivor space 0 utilization (kB).表示survivor 0區(qū)使用了的大小
S1U: Survivor space 1 utilization (kB).表示survivor 1區(qū)使用了的大小
EC: Current eden space capacity (kB).表示eden區(qū)總大小
EU: Eden space utilization (kB).表示eden區(qū)使用了的大小
OC: Current old space capacity (kB).表示old區(qū)總大小
OU: Old space utilization (kB).表示old區(qū)使用了的大小
MC: Metaspace capacity (kB).表示Metaspace區(qū)總大小
MU: Metacspace utilization (kB).表示Metaspace區(qū)使用了的大小
CCSC: Compressed class space capacity (kB).表示壓縮類空間總量
CCSU: Compressed class space used (kB).表示壓縮類空間使用量
YGC: Number of young generation garbage collection events.表示Young GC的次數(shù)
YGCT: Young generation garbage collection time.表示Young GC的時間
FGC: Number of full GC events.表示full GC的次數(shù)
FGCT: Full garbage collection time.表示full GC的時間
GCT: Total garbage collection time.表示總的 GC的時間
3.3 JIT編譯
3.3.1 -compiler參數(shù)
MacBook-Pro:dubbo-learn chuanzhou$ jstat -compiler 29159 1000 5
Compiled Failed Invalid Time FailedType FailedMethod
1284 0 0 3.50 0
1284 0 0 3.50 0
1284 0 0 3.50 0
1284 0 0 3.50 0
1284 0 0 3.50 0
- Compiled：表示編譯成功的方法數(shù)量
- Failed：表示編譯失敗的方法數(shù)量
- Invalid：表示編譯無效的方法數(shù)量
- Time：編譯所花費的時間
- FailedType：編譯失敗類型
- FailedMethod：編譯失敗方法
3.3.2 -printcompilation參數(shù)
4、jmap+MAT實戰(zhàn)內(nèi)存溢出
模擬內(nèi)存溢出：
@RestController
public class MemoryController {
private List<User> userList = new ArrayList<User>();
private List<Class<?>> classList = new ArrayList<Class<?>>();
/**
* -Xmx32M -Xms32M
* */
@GetMapping("/heap")
public String heap() {
int i=0;
while(true) {
userList.add(new User(i++, UUID.randomUUID().toString()));
}
}
/**
* -XX:MetaspaceSize=32M -XX:MaxMetaspaceSize=32M
* */
@GetMapping("/nonheap")
public String nonheap() {
while(true) {
classList.addAll(Metaspace.createClasses());
}
}
}
package com.imooc.monitor_tuning.chapter2;
import java.util.ArrayList;
import java.util.List;
import org.objectweb.asm.ClassWriter;
import org.objectweb.asm.MethodVisitor;
import org.objectweb.asm.Opcodes;
/*
* https://blog.csdn.net/bolg_hero/article/details/78189621
* 繼承ClassLoader是為了方便調(diào)用defineClass方法，因為該方法的定義為protected
* */
public class Metaspace extends ClassLoader {
public static List<Class<?>> createClasses() {
// 類持有
List<Class<?>> classes = new ArrayList<Class<?>>();
// 循環(huán)1000w次生成1000w個不同的類。
for (int i = 0; i < 10000000; ++i) {
ClassWriter cw = new ClassWriter(0);
// 定義一個類名稱為Class{i}，它的訪問域為public，父類為java.lang.Object，不實現(xiàn)任何接口
cw.visit(Opcodes.V1_1, Opcodes.ACC_PUBLIC, "Class" + i, null,
"java/lang/Object", null);
// 定義構(gòu)造函數(shù)<init>方法
MethodVisitor mw = cw.visitMethod(Opcodes.ACC_PUBLIC, "<init>",
"()V", null, null);
// 第一個指令為加載this
mw.visitVarInsn(Opcodes.ALOAD, 0);
// 第二個指令為調(diào)用父類Object的構(gòu)造函數(shù)
mw.visitMethodInsn(Opcodes.INVOKESPECIAL, "java/lang/Object",
"<init>", "()V");
// 第三條指令為return
mw.visitInsn(Opcodes.RETURN);
mw.visitMaxs(1, 1);
mw.visitEnd();
Metaspace test = new Metaspace();
byte[] code = cw.toByteArray();
// 定義類
Class<?> exampleClass = test.defineClass("Class" + i, code, 0, code.length);
classes.add(exampleClass);
}
return classes;
}
}
package com.imooc.monitor_tuning.chapter2;
public class User {
private int id;
private String name;
public User(int id, String name) {
super();
this.id = id;
this.name = name;
}
public int getId() {
return id;
}
public void setId(int id) {
this.id = id;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
}
設置啟動參數(shù)：
啟動參數(shù)
啟動application，發(fā)現(xiàn)出現(xiàn)內(nèi)存溢出
4.1 如何導出內(nèi)存溢出映像文件
4.2 內(nèi)存溢出自動導出
-XX:+HeapDumpOnOutOfMemoryError
-XX:HeapDumpPath=./
4.3 使用jmap命令手動導出
格式：jmap -dump:format=b,file=路徑/heap.hprof 進程id
其他命令：jmap -heap 進程id 查看堆信息
[root@izwz93osmk5vi5qwqyscxaz bin]# ./jmap -heap 9723
Attaching to process ID 9723, please wait...
Debugger attached successfully.
Server compiler detected.
JVM version is 25.72-b15
using thread-local object allocation.
Mark Sweep Compact GC
Heap Configuration:
MinHeapFreeRatio = 40
MaxHeapFreeRatio = 70
MaxHeapSize = 482344960 (460.0MB)
NewSize = 10485760 (10.0MB)
MaxNewSize = 160759808 (153.3125MB)
OldSize = 20971520 (20.0MB)
NewRatio = 2
SurvivorRatio = 8
MetaspaceSize = 21807104 (20.796875MB)
CompressedClassSpaceSize = 1073741824 (1024.0MB)
MaxMetaspaceSize = 17592186044415 MB
G1HeapRegionSize = 0 (0.0MB)
Heap Usage:
New Generation (Eden + 1 Survivor Space):
capacity = 32178176 (30.6875MB)
used = 16081160 (15.336189270019531MB)
free = 16097016 (15.351310729980469MB)
49.97536218336303% used
Eden Space:
capacity = 28639232 (27.3125MB)
used = 16054760 (15.311012268066406MB)
free = 12584472 (12.001487731933594MB)
56.058626153103546% used
From Space:
capacity = 3538944 (3.375MB)
used = 26400 (0.025177001953125MB)
free = 3512544 (3.349822998046875MB)
0.7459852430555556% used
To Space:
capacity = 3538944 (3.375MB)
used = 0 (0.0MB)
free = 3538944 (3.375MB)
0.0% used
tenured generation:
capacity = 71221248 (67.921875MB)
used = 57115304 (54.469398498535156MB)
free = 14105944 (13.452476501464844MB)
80.19419148622613% used
27532 interned Strings occupying 3194040 bytes.
4.4 使用MAT分析映像文件
MAT分析
- Class Name：類名
- Objects：對象數(shù)量
- Shallow Heap：
- Retained Heap：占用的內(nèi)存大小
右鍵查看com.imooc.monitor_tuning.chapter2.User的強引用
image.png
image.png
也可以查看對象樹：
對象樹
5、jstack實戰(zhàn)死循環(huán)與死鎖
格式：jstack 進程id
2018-09-05 07:59:21
Full thread dump Java HotSpot(TM) 64-Bit Server VM (25.72-b15 mixed mode):
"Attach Listener" #16 daemon prio=9 os_prio=0 tid=0x00007f3d9c001000 nid=0x521f waiting on condition [0x0000000000000000]
java.lang.Thread.State: RUNNABLE
"localhost-startStop-1" #15 daemon prio=5 os_prio=0 tid=0x00007f3dac002800 nid=0x5208 runnable [0x00007f3da15d1000]
java.lang.Thread.State: RUNNABLE
at java.io.FileInputStream.readBytes(Native Method)
at java.io.FileInputStream.read(FileInputStream.java:255)
at sun.security.provider.SeedGenerator$URLSeedGenerator.getSeedBytes(SeedGenerator.java:539)
at sun.security.provider.SeedGenerator.generateSeed(SeedGenerator.java:144)
at sun.security.provider.SecureRandom$SeederHolder.<clinit>(SecureRandom.java:203)
at sun.security.provider.SecureRandom.engineNextBytes(SecureRandom.java:221)
- locked <0x00000000e3e90be0> (a sun.security.provider.SecureRandom)
at java.security.SecureRandom.nextBytes(SecureRandom.java:468)
- locked <0x00000000e3e910c0> (a java.security.SecureRandom)
at java.security.SecureRandom.next(SecureRandom.java:491)
at java.util.Random.nextInt(Random.java:329)
at org.apache.catalina.util.SessionIdGeneratorBase.createSecureRandom(SessionIdGeneratorBase.java:240)
at org.apache.catalina.util.SessionIdGeneratorBase.getRandomBytes(SessionIdGeneratorBase.java:174)
at org.apache.catalina.util.StandardSessionIdGenerator.generateSessionId(StandardSessionIdGenerator.java:34)
at org.apache.catalina.util.SessionIdGeneratorBase.generateSessionId(SessionIdGeneratorBase.java:167)
at org.apache.catalina.util.SessionIdGeneratorBase.startInternal(SessionIdGeneratorBase.java:260)
at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:145)
- locked <0x00000000e3e90730> (a org.apache.catalina.util.StandardSessionIdGenerator)
at org.apache.catalina.session.ManagerBase.startInternal(ManagerBase.java:717)
at org.apache.catalina.session.StandardManager.startInternal(StandardManager.java:352)
- locked <0x00000000e42eefb0> (a org.apache.catalina.session.StandardManager)
at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:145)
- locked <0x00000000e42eefb0> (a org.apache.catalina.session.StandardManager)
at org.apache.catalina.core.StandardContext.startInternal(StandardContext.java:5339)
- locked <0x00000000ed3c6ca0> (a org.apache.catalina.core.StandardContext)
at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:145)
- locked <0x00000000ed3c6ca0> (a org.apache.catalina.core.StandardContext)
at org.apache.catalina.core.ContainerBase.addChildInternal(ContainerBase.java:753)
at org.apache.catalina.core.ContainerBase.addChild(ContainerBase.java:729)
at org.apache.catalina.core.StandardHost.addChild(StandardHost.java:717)
at org.apache.catalina.startup.HostConfig.deployWAR(HostConfig.java:974)
at org.apache.catalina.startup.HostConfig$DeployWar.run(HostConfig.java:1850)
at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:511)
at java.util.concurrent.FutureTask.run(FutureTask.java:266)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
at java.lang.Thread.run(Thread.java:745)
"Catalina-startStop-1" #14 daemon prio=5 os_prio=0 tid=0x00007f3dc4437000 nid=0x5207 waiting on condition [0x00007f3da16d2000]
java.lang.Thread.State: WAITING (parking)
at sun.misc.Unsafe.park(Native Method)
- parking to wait for <0x00000000ed3c6fc0> (a java.util.concurrent.FutureTask)
at java.util.concurrent.locks.LockSupport.park(LockSupport.java:175)
at java.util.concurrent.FutureTask.awaitDone(FutureTask.java:429)
at java.util.concurrent.FutureTask.get(FutureTask.java:191)
at org.apache.catalina.startup.HostConfig.deployWARs(HostConfig.java:766)
at org.apache.catalina.startup.HostConfig.deployApps(HostConfig.java:436)
at org.apache.catalina.startup.HostConfig.start(HostConfig.java:1580)
at org.apache.catalina.startup.HostConfig.lifecycleEvent(HostConfig.java:322)
at org.apache.catalina.util.LifecycleSupport.fireLifecycleEvent(LifecycleSupport.java:95)
at org.apache.catalina.util.LifecycleBase.fireLifecycleEvent(LifecycleBase.java:90)
at org.apache.catalina.util.LifecycleBase.setStateInternal(LifecycleBase.java:388)
- locked <0x00000000ed03ec38> (a org.apache.catalina.core.StandardHost)
at org.apache.catalina.util.LifecycleBase.setState(LifecycleBase.java:333)
- locked <0x00000000ed03ec38> (a org.apache.catalina.core.StandardHost)
at org.apache.catalina.core.ContainerBase.startInternal(ContainerBase.java:960)
- locked <0x00000000ed03ec38> (a org.apache.catalina.core.StandardHost)
at org.apache.catalina.core.StandardHost.startInternal(StandardHost.java:871)
- locked <0x00000000ed03ec38> (a org.apache.catalina.core.StandardHost)
at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:145)
- locked <0x00000000ed03ec38> (a org.apache.catalina.core.StandardHost)
at org.apache.catalina.core.ContainerBase$StartChild.call(ContainerBase.java:1408)
at org.apache.catalina.core.ContainerBase$StartChild.call(ContainerBase.java:1398)
at java.util.concurrent.FutureTask.run(FutureTask.java:266)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
at java.lang.Thread.run(Thread.java:745)
"NioBlockingSelector.BlockPoller-2" #13 daemon prio=5 os_prio=0 tid=0x00007f3dc4429800 nid=0x5206 runnable [0x00007f3da17d4000]
java.lang.Thread.State: RUNNABLE
at sun.nio.ch.EPollArrayWrapper.epollWait(Native Method)
at sun.nio.ch.EPollArrayWrapper.poll(EPollArrayWrapper.java:269)
at sun.nio.ch.EPollSelectorImpl.doSelect(EPollSelectorImpl.java:93)
at sun.nio.ch.SelectorImpl.lockAndDoSelect(SelectorImpl.java:86)
- locked <0x00000000ed3c75a8> (a sun.nio.ch.Util$2)
- locked <0x00000000ed3c75b8> (a java.util.Collections$UnmodifiableSet)
- locked <0x00000000ed3c7560> (a sun.nio.ch.EPollSelectorImpl)
at sun.nio.ch.SelectorImpl.select(SelectorImpl.java:97)
at org.apache.tomcat.util.net.NioBlockingSelector$BlockPoller.run(NioBlockingSelector.java:301)
"NioBlockingSelector.BlockPoller-1" #12 daemon prio=5 os_prio=0 tid=0x00007f3dc440e800 nid=0x5205 runnable [0x00007f3da18d5000]
java.lang.Thread.State: RUNNABLE
at sun.nio.ch.EPollArrayWrapper.epollWait(Native Method)
at sun.nio.ch.EPollArrayWrapper.poll(EPollArrayWrapper.java:269)
at sun.nio.ch.EPollSelectorImpl.doSelect(EPollSelectorImpl.java:93)
at sun.nio.ch.SelectorImpl.lockAndDoSelect(SelectorImpl.java:86)
- locked <0x00000000ed3c77e0> (a sun.nio.ch.Util$2)
- locked <0x00000000ed3c77f0> (a java.util.Collections$UnmodifiableSet)
- locked <0x00000000ed3c7798> (a sun.nio.ch.EPollSelectorImpl)
at sun.nio.ch.SelectorImpl.select(SelectorImpl.java:97)
at org.apache.tomcat.util.net.NioBlockingSelector$BlockPoller.run(NioBlockingSelector.java:301)
"GC Daemon" #11 daemon prio=2 os_prio=0 tid=0x00007f3dc4356800 nid=0x5204 in Object.wait() [0x00007f3dc81a0000]
java.lang.Thread.State: TIMED_WAITING (on object monitor)
at java.lang.Object.wait(Native Method)
- waiting on <0x00000000ed0d57f0> (a sun.misc.GC$LatencyLock)
at sun.misc.GC$Daemon.run(GC.java:117)
- locked <0x00000000ed0d57f0> (a sun.misc.GC$LatencyLock)
"AsyncFileHandlerWriter-789451787" #10 daemon prio=5 os_prio=0 tid=0x00007f3dc4105000 nid=0x5203 waiting on condition [0x00007f3dc8338000]
java.lang.Thread.State: TIMED_WAITING (parking)
at sun.misc.Unsafe.park(Native Method)
- parking to wait for <0x00000000ecec1210> (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.LinkedBlockingDeque.pollFirst(LinkedBlockingDeque.java:522)
at java.util.concurrent.LinkedBlockingDeque.poll(LinkedBlockingDeque.java:684)
at org.apache.juli.AsyncFileHandler$LoggerThread.run(AsyncFileHandler.java:153)
"Service Thread" #7 daemon prio=9 os_prio=0 tid=0x00007f3dc40b3800 nid=0x5201 runnable [0x0000000000000000]
java.lang.Thread.State: RUNNABLE
"C1 CompilerThread1" #6 daemon prio=9 os_prio=0 tid=0x00007f3dc40b0800 nid=0x5200 waiting on condition [0x0000000000000000]
java.lang.Thread.State: RUNNABLE
"C2 CompilerThread0" #5 daemon prio=9 os_prio=0 tid=0x00007f3dc40ae800 nid=0x51ff waiting on condition [0x0000000000000000]
java.lang.Thread.State: RUNNABLE
"Signal Dispatcher" #4 daemon prio=9 os_prio=0 tid=0x00007f3dc40ad000 nid=0x51fe runnable [0x0000000000000000]
java.lang.Thread.State: RUNNABLE
"Finalizer" #3 daemon prio=8 os_prio=0 tid=0x00007f3dc407a000 nid=0x51fd in Object.wait() [0x00007f3dc893e000]
java.lang.Thread.State: WAITING (on object monitor)
at java.lang.Object.wait(Native Method)
- waiting on <0x00000000ecec2320> (a java.lang.ref.ReferenceQueue$Lock)
at java.lang.ref.ReferenceQueue.remove(ReferenceQueue.java:143)
- locked <0x00000000ecec2320> (a java.lang.ref.ReferenceQueue$Lock)
at java.lang.ref.ReferenceQueue.remove(ReferenceQueue.java:164)
at java.lang.ref.Finalizer$FinalizerThread.run(Finalizer.java:209)
"Reference Handler" #2 daemon prio=10 os_prio=0 tid=0x00007f3dc4075000 nid=0x51fc in Object.wait() [0x00007f3dc8a3f000]
java.lang.Thread.State: WAITING (on object monitor)
at java.lang.Object.wait(Native Method)
- waiting on <0x00000000ecec24d8> (a java.lang.ref.Reference$Lock)
at java.lang.Object.wait(Object.java:502)
at java.lang.ref.Reference.tryHandlePending(Reference.java:191)
- locked <0x00000000ecec24d8> (a java.lang.ref.Reference$Lock)
at java.lang.ref.Reference$ReferenceHandler.run(Reference.java:153)
"main" #1 prio=5 os_prio=0 tid=0x00007f3dc4009000 nid=0x51fa waiting on condition [0x00007f3dcc417000]
java.lang.Thread.State: WAITING (parking)
at sun.misc.Unsafe.park(Native Method)
- parking to wait for <0x00000000ed3c7340> (a java.util.concurrent.FutureTask)
at java.util.concurrent.locks.LockSupport.park(LockSupport.java:175)
at java.util.concurrent.FutureTask.awaitDone(FutureTask.java:429)
at java.util.concurrent.FutureTask.get(FutureTask.java:191)
at org.apache.catalina.core.ContainerBase.startInternal(ContainerBase.java:943)
- locked <0x00000000ecfb7038> (a org.apache.catalina.core.StandardEngine)
at org.apache.catalina.core.StandardEngine.startInternal(StandardEngine.java:262)
- locked <0x00000000ecfb7038> (a org.apache.catalina.core.StandardEngine)
at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:145)
- locked <0x00000000ecfb7038> (a org.apache.catalina.core.StandardEngine)
at org.apache.catalina.core.StandardService.startInternal(StandardService.java:441)
- locked <0x00000000ecfb7038> (a org.apache.catalina.core.StandardEngine)
at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:145)
- locked <0x00000000ecfa2330> (a org.apache.catalina.core.StandardService)
at org.apache.catalina.core.StandardServer.startInternal(StandardServer.java:789)
- locked <0x00000000ecf4e258> (a java.lang.Object)
at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:145)
- locked <0x00000000ecf1c578> (a org.apache.catalina.core.StandardServer)
at org.apache.catalina.startup.Catalina.start(Catalina.java:641)
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 org.apache.catalina.startup.Bootstrap.start(Bootstrap.java:349)
at org.apache.catalina.startup.Bootstrap.main(Bootstrap.java:483)
"VM Thread" os_prio=0 tid=0x00007f3dc406d800 nid=0x51fb runnable
"VM Periodic Task Thread" os_prio=0 tid=0x00007f3dc40b7000 nid=0x5202 waiting on condition
JNI global references: 59
- localhost-startStop-1：線程名
- daemon：后臺線程
- prio：優(yōu)先級
- os_prio：系統(tǒng)優(yōu)先級
- tid：線程id
- nid：操作系統(tǒng)id
- java.lang.Thread.State：線程狀態(tài)；NEW-線程尚未啟動， RUNNABLE- 線程運行中，BLOCKED-等待一個鎖， WAITINH-等待另一個線程， TIMED_WAITING-限時等待另一個線程， TERMINATED-已退出
5.1 實戰(zhàn)死循環(huán)
import java.util.ArrayList;
import java.util.List;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;
@RestController
public class CpuController {
/**
* 死循環(huán)
* */
@RequestMapping("/loop")
public List<Long> loop(){
String data = "{\"data\":[{\"partnerid\":]";
return getPartneridsFromJson(data);
}
private Object lock1 = new Object();
private Object lock2 = new Object();
/**
* 死鎖
* */
@RequestMapping("/deadlock")
public String deadlock(){
new Thread(()->{
synchronized(lock1) {
try {Thread.sleep(1000);}catch(Exception e) {}
synchronized(lock2) {
System.out.println("Thread1 over");
}
}
}) .start();
new Thread(()->{
synchronized(lock2) {
try {Thread.sleep(1000);}catch(Exception e) {}
synchronized(lock1) {
System.out.println("Thread2 over");
}
}
}) .start();
return "deadlock";
}
public static List<Long> getPartneridsFromJson(String data){
//{\"data\":[{\"partnerid\":982,\"count\":\"10000\",\"cityid\":\"11\"},{\"partnerid\":983,\"count\":\"10000\",\"cityid\":\"11\"},{\"partnerid\":984,\"count\":\"10000\",\"cityid\":\"11\"}]}
//上面是正常的數(shù)據(jù)
List<Long> list = new ArrayList<Long>(2);
if(data == null || data.length() <= 0){
return list;
}
int datapos = data.indexOf("data");
if(datapos < 0){
return list;
}
int leftBracket = data.indexOf("[",datapos);
int rightBracket= data.indexOf("]",datapos);
if(leftBracket < 0 || rightBracket < 0){
return list;
}
String partners = data.substring(leftBracket+1,rightBracket);
if(partners == null || partners.length() <= 0){
return list;
}
while(partners!=null && partners.length() > 0){
int idpos = partners.indexOf("partnerid");
if(idpos < 0){
break;
}
int colonpos = partners.indexOf(":",idpos);
int commapos = partners.indexOf(",",idpos);
if(colonpos < 0 || commapos < 0){
//partners = partners.substring(idpos+"partnerid".length());//1
continue;
}
String pid = partners.substring(colonpos+1,commapos);
if(pid == null || pid.length() <= 0){
//partners = partners.substring(idpos+"partnerid".length());//2
continue;
}
try{
list.add(Long.parseLong(pid));
}catch(Exception e){
//do nothing
}
partners = partners.substring(commapos);
}
return list;
}
}
訪問/loop端點三次，然后使用top命令：
#導出線程堆棧
$ jstack 7930 > 7930.txt
#打印該進程下的線程
$ top -p 7930 -H
#將十進制線程id轉(zhuǎn)換為16進制
$ printf "%x" 8247
2037
然后在導出的7930.txt文件中找到2037
死循環(huán)
訪問/loop端點，制造死循環(huán)，使用jstack命令導出線程堆棧信息：
死鎖
最后一行已提示：Found 1 deadlock
相關資料：
jdk8工具集
https://docs.oracle.com/javase/8/docs/technotes/tools/unix/index.html
Troubleshooting
https://docs.oracle.com/javase/8/docs/technotes/guides/troubleshoot/
jps
https://docs.oracle.com/javase/8/docs/technotes/tools/unix/jps.html
jinfo
https://docs.oracle.com/javase/8/docs/technotes/tools/unix/jinfo.html
jstat
https://docs.oracle.com/javase/8/docs/technotes/tools/unix/jstat.html
jmap：
https://docs.oracle.com/javase/8/docs/technotes/tools/unix/jmap.html
mat:
http://www.eclipse.org/mat/downloads.php
jstack：
https://docs.oracle.com/javase/8/docs/technotes/tools/unix/jstack.html
java線程的狀態(tài)
https://docs.oracle.com/javase/8/docs/technotes/guides/troubleshoot/tooldescr034.html
java線程狀態(tài)轉(zhuǎn)化：
https://mp.weixin.qq.com/s/GsxeFM7QWuR--Kbpb7At2w
死循環(huán)導致CPU負載高
https://blog.csdn.net/goldenfish1919/article/details/8755378
正則表達式導致死循環(huán)：
https://blog.csdn.net/goldenfish1919/article/details/49123787
