文章目录
JDK 中与常用命令行工具
jps
$> jps
7584 Application
16433 AdminApplication
14209 Jps
5813 Bootstrap
5575 TestApplication
7160 Application
6010 Bootstrap
6715 Bootstrap
3981 QuorumPeerMain
6527 jar
$> jps -help
usage: jps [-help]
jps [-q] [-mlvV] [<hostid>]
Definitions:
<hostid>: <hostname>[:<port>]
- l 显示类的完整信息
- v 显示启动时的 Java 配置选项
jstat
$> jstat -help
Usage: jstat -help|-options
jstat -<option> [-t] [-h<lines>] <vmid> [<interval> [<count>]]
Definitions:
<option> 通过 -options 可以查看有哪些option
<vmid> 进程id，如果是远程格式如下：<远程的进程id>[@<hostname>[:<port>]]
<lines> 打印多少行之后再次显示一下表头.
<interval> 打印间隔时间格式为:<n>["ms"|"s"]
<count> 重复打印的次数，如果设置了 interval 而不设置时间，则一直打印.
-J<flag> 将 <flag> 的值传递给运行时系统.
-t 程序执行时长
-h<lines> 打印多少行之后再次显示一下表头
$> jstat -options
-class 显示 ClassLoader 的相关信息
-compiler 显示 JIT 编译的信息
-gc 显示 GC 相关信息
-gccapacity 类似 -gc
-gccause 显示发生 GC 的原因
-gcmetacapacity
-gcnew 新生代信息
-gcnewcapacity 类似于 -gcnew
-gcold 老年代信息
-gcoldcapacity 类似于 -gcnew
-gcutil
-printcompilation 显示 JIT 编译的信息
-gc 示例
$> jstat -gc 进程id 1s 100
S0C S1C S0U S1U EC EU OC OU MC MU CCSC CCSU YGC YGCT FGC FGCT GCT
512.0 512.0 128.0 0.0 36864.0 29170.4 152064.0 72123.0 105088.0 99428.9 12416.0 11352.7 920 22.131 4 1.018 23.149
S0C：幸存者0区的总内存大小
S0U：幸存者0区已经使用的内存大小
EC、EU： Eden 区的总内存大小和已经使用的内存大小
OC、OU：老年代的内存信息
MC、MU：元空间的内存信息
YGC：YoungGC 的次数
YGCT：YoungGC 的时间
FGC：FGC 的次数
FGCT：FGC 的时间
GCT：总 GC 的时间
jinfo
$> jinfo -help
Usage:
jinfo [option] <pid>
(to connect to running process)
jinfo [option] <executable <core>
(to connect to a core file)
jinfo [option] [server_id@]<remote server IP or hostname>
(to connect to remote debug server)
where <option> is one of:
-flag <name> to print the value of the named VM flag
-flag [+|-]<name> to enable or disable the named VM flag
-flag <name>=<value> to set the named VM flag to the given value
-flags to print VM flags
-sysprops to print Java system properties
<no option> to print both of the above
-h | -help to print this help message
示例
$> jinfo -flags 进程id
Attaching to process ID 进程id, please wait...
Debugger attached successfully.
Server compiler detected.
JVM version is 25.181-b13
Non-default VM flags: -XX:CICompilerCount=3 -XX:InitialHeapSize=130023424 -XX:MaxHeapSize=2051014656 -XX:MaxNewSize=683671552 -XX:MinHeapDeltaBytes=524288 -XX:NewSize=42991616 -XX:OldSize=87031808 -XX:+UseCompressedClassPointers -XX:+UseCompressedOops -XX:+UseParallelGC
Command line:
$> java -XX:+PrintFlagsFinal -version | grep manageable
intx CMSAbortablePrecleanWaitMillis = 100 {manageable}
intx CMSTriggerInterval = -1 {manageable}
intx CMSWaitDuration = 2000 {manageable}
bool HeapDumpAfterFullGC = false {manageable}
bool HeapDumpBeforeFullGC = false {manageable}
bool HeapDumpOnOutOfMemoryError = false {manageable}
ccstr HeapDumpPath = {manageable}
uintx MaxHeapFreeRatio = 100 {manageable}
uintx MinHeapFreeRatio = 0 {manageable}
bool PrintClassHistogram = false {manageable}
bool PrintClassHistogramAfterFullGC = false {manageable}
bool PrintClassHistogramBeforeFullGC = false {manageable}
bool PrintConcurrentLocks = false {manageable}
bool PrintGC = false {manageable}
bool PrintGCDateStamps = false {manageable}
bool PrintGCDetails = false {manageable}
bool PrintGCID = false {manageable}
bool PrintGCTimeStamps = false {manageable}
jmap
$> jmap -help
Usage:
jmap [option] <pid>
(to connect to running process)
jmap [option] <executable <core>
(to connect to a core file)
jmap [option] [server_id@]<remote server IP or hostname>
(to connect to remote debug server)
where <option> is one of:
<none> to print same info as Solaris pmap
-heap to print java heap summary
-histo[:live] to print histogram of java object heap; if the "live"
suboption is specified, only count live objects
-clstats to print class loader statistics
-finalizerinfo to print information on objects awaiting finalization
-dump:<dump-options> to dump java heap in hprof binary format
dump-options:
live dump only live objects; if not specified,
all objects in the heap are dumped.
format=b binary format
file=<file> dump heap to <file>
Example: jmap -dump:live,format=b,file=heap.bin <pid>
-F force. Use with -dump:<dump-options> <pid> or -histo
to force a heap dump or histogram when <pid> does not
respond. The "live" suboption is not supported
in this mode.
-h | -help to print this help message
-J<flag> to pass <flag> directly to the runtime system
导出 dump 文件
## jmap -dump:format=b,file=<fileName.hprof> <pid>
## 只导出存活对象 jmap -dump:live,format=b,file=<fileName.hprof> <pid>
$> jmap -dump:format=b,file=test.hprof 进程id
Dumping heap to /home/test/test.hprof ...
Heap dump file created
- -XX:HeapDumpPath=path
将 OutOfMemoryError 转储到 .hprof 文件，此设置虚配合 -XX:+HeapDumpOnOutOfMemoryError 一起使用
- -XX:+HeapDumpOnOutOfMemoryError
当出现 java.lang.OutOfMemoryError 异常，则将根据 -XX:HeapDumpPath=path 配置输出 .hprof 文件
查看堆内存信息
## jmap -heap <pid> 显示堆内存当前的使用情况
## jmap -histo[:live] <pid> 统计所有[存活]的对象并统计其占用内存信息以及对象个数等
$> jmap -heap 进程id
Attaching to process ID 进程id, please wait...
Debugger attached successfully.
Server compiler detected.
JVM version is 25.181-b13
using thread-local object allocation.
Parallel GC with 4 thread(s)
# 堆空间的配置信息
Heap Configuration:
MinHeapFreeRatio = 0
MaxHeapFreeRatio = 100
MaxHeapSize = 2051014656 (1956.0MB)
NewSize = 42991616 (41.0MB)
MaxNewSize = 683671552 (652.0MB)
OldSize = 87031808 (83.0MB)
NewRatio = 2
SurvivorRatio = 8
MetaspaceSize = 21807104 (20.796875MB)
CompressedClassSpaceSize = 1073741824 (1024.0MB)
MaxMetaspaceSize = 17592186044415 MB
G1HeapRegionSize = 0 (0.0MB)
Heap Usage:
PS Young Generation
Eden Space: # Eden 区信息
capacity = 38797312 (37.0MB)
used = 35691760 (34.03831481933594MB)
free = 3105552 (2.9616851806640625MB)
91.9954454576647% used
From Space: # from 区信息
capacity = 524288 (0.5MB)
used = 131072 (0.125MB)
free = 393216 (0.375MB)
25.0% used
To Space: # to 区信息
capacity = 524288 (0.5MB)
used = 0 (0.0MB)
free = 524288 (0.5MB)
0.0% used
PS Old Generation # 老年代信息
capacity = 195559424 (186.5MB)
used = 54819320 (52.27977752685547MB)
free = 140740104 (134.22022247314453MB)
28.03205229322009% used
34583 interned Strings occupying 4040496 bytes.
jstack
$> jstack -help
Usage:
jstack [-l] <pid>
(to connect to running process) # 连接正在执行的进程
jstack -F [-m] [-l] <pid>
(to connect to a hung process) # 连接到挂起的进程
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) # 强制打印
-m to print both java and native frames (mixed mode) # 打印具有 Java 和本机 C/C++ 帧的混合模式堆栈跟踪
-l long listing. Prints additional information about locks # 打印有关锁的附加信息
-h or -help to print this help message
示例
$> jstack 进程id
2023-10-10 21:28:17
Full thread dump Java HotSpot(TM) 64-Bit Server VM (25.181-b13 mixed mode):
"Attach Listener" #440036 daemon prio=9 os_prio=0 tid=0x00007fd96001f800 nid=0x324c waiting on condition [0x0000000000000000]
java.lang.Thread.State: RUNNABLE # 当前线程的状态 RUNNABLE 、WAITING都算正常 TIME_WAITTING 程序 sleep 中
"Java2D Disposer" #77543 daemon prio=10 os_prio=0 tid=0x00007fd91005b800 nid=0x45e0 in Object.wait() [0x00007fd900dd4000]
java.lang.Thread.State: WAITING (on object monitor)
at java.lang.Object.wait(Native Method)
at java.lang.ref.ReferenceQueue.remove(ReferenceQueue.java:144)
- locked <0x0000000088ce20b0> (a java.lang.ref.ReferenceQueue$Lock)
at java.lang.ref.ReferenceQueue.remove(ReferenceQueue.java:165)
at sun.java2d.Disposer.run(Disposer.java:148)
at java.lang.Thread.run(Thread.java:748)
"logback-8" #50912 daemon prio=5 os_prio=0 tid=0x00007fd9740d3800 nid=0x296c waiting on condition [0x00007fd8ffecf000]
java.lang.Thread.State: WAITING (parking)
at sun.misc.Unsafe.park(Native Method)
- parking to wait for <0x00000000885336a0> (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$DelayedWorkQueue.take(ScheduledThreadPoolExecutor.java:1081)
at java.util.concurrent.ScheduledThreadPoolExecutor$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$Worker.run(ThreadPoolExecutor.java:624)
at java.lang.Thread.run(Thread.java:748)
"logback-7" #44036 daemon prio=5 os_prio=0 tid=0x00007fd9740d3000 nid=0x75e8 waiting on condition [0x00007fd8fffd0000]
java.lang.Thread.State: WAITING (parking)
at sun.misc.Unsafe.park(Native Method)
- parking to wait for <0x00000000885336a0> (a java.util.concurrent.locks.AbstractQueuedSynchronizer$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:1081)
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 java.lang.Thread.run(Thread.java:748)
"logback-6" #37255 daemon prio=5 os_prio=0 tid=0x00007fd97407a000 nid=0x32ac waiting on condition [0x00007fd93e4b7000]
java.lang.Thread.State: WAITING (parking)
at sun.misc.Unsafe.park(Native Method)
- parking to wait for <0x00000000885336a0> (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$DelayedWorkQueue.take(ScheduledThreadPoolExecutor.java:1081)
at java.util.concurrent.ScheduledThreadPoolExecutor$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 java.lang.Thread.run(Thread.java:748)
JVM 可视化分析工具
- jconsole JDK bin 目录下
- jvisualvm JDK bin 目录下，也可以直接下载相关 Visualvm 软件。idea 中可以使用 VisualVM Launcher 插件来快速启动。Visualvm 本身也有许多有用的插件。
- JMC JDK bin 目录下
- Eclipse MAT（Memory Analyzer Tool） Eclipse 推出的内存分析工具，也可以在 Eclipse 中通过插件引入。其特点是开源免费，老牌 IDE Eclipse 出品，功能也挺多的，可直接下载 MAT 软件启动，也可以在 Eclipse 中通过插件引入。
- JProfiler：商业付费，idea 有快速启动其的同名插件。界面清晰，功能强大，目前最新的 14.0 版本是支持中文显示界面的。14.0 版本官方教程文档 https://www.ej-technologies.com/resources/jprofiler/v/14.0/help_zh_CN/doc/main/introduction.html
- Arthas：阿里开源，它是可以在生产环境进行运行分析的，官方说明是，它可以不停止应用对应用进行分析，且不会像远程调试一样会阻塞应用执行。官网地址为：https://arthas.aliyun.com/
