JAVA基础之虚拟机故障处理工具 java虚拟机

今天学习了《深入理解java虚拟机》的故障处理工具，都是一些小命令，不复杂，只不过有些命令在prod环境不要使用，jmap这种，在动辄几G的内存的pod中，生成一次文件可能就导致了环境停止，这时如果还有大量请求进来，这个pod估计在生成dump文件之前就崩溃了。 jps命令查看java进程

buxuesongdeMacBook-Pro:~ buxuesong$ jps -l 1121 /Users/buxuesong/Documents/git_code/account/account-api/target/account-api-1.3.0-SNAPSHOT.jar 1131 sun.tools.jps.Jps buxuesongdeMacBook-Pro:~ buxuesong$ ps -ef|grep 1121 501112111200 11:01下午 ttys0000:24.41 /usr/bin/java -jar /Users/buxuesong/Documents/git_code/account/account-api/target/account-api-1.3.0-SNAPSHOT.jar 501113811250 11:02下午 ttys0010:00.00 grep 1121 buxuesongdeMacBook-Pro:~ buxuesong$

jstat命令用于监视虚拟机各种运行状态信息

buxuesongdeMacBook-Pro:~ buxuesong$ jstat -gcutil 1121 S0S1EOMCCSYGCYGCTFGCFGCTGCT 0.0096.7863.5223.5295.1292.69110.10120.2110.311 //1121命令下，2个Survivor区（S0、S1，表示Survivor0、Survivor1）,S0为空，S1占用96.78%，新生代Eden区（E，表示Eden）使用了63.52% //老年代（O，表示Old）和永久代（M）则分别使用了23.52%和95.12%的空间 //CCS，压缩使用比例92.69% //程序运行以来共发生Minor GC（YGC，表示Young GC）11次，总耗时0.101秒； //发生Full GC（FGC，表示Full GC）2次，总耗时（FGCT，表示Full GCTime）为0.211秒；所有GC总耗时（GCT，表示GC Time）为0.311秒。

【JAVA基础之虚拟机故障处理工具】jinfo命令实时查看和调整虚拟机各项参数

buxuesongdeMacBook-Pro:~ buxuesong$ jinfo -flag CMSInitiatingOccupancyFraction 1835 -XX:CMSInitiatingOccupancyFraction=-1

jmap（Memory Map for Java）命令用于生成堆转储快照（一般称为heapdump或dump文件）

buxuesongdeMacBook-Pro:~ buxuesong$ jmap -dump:format=b,file=account.dump 1868 Dumping heap to /Users/buxuesong/account.dump ... Heap dump file created

jhat（JVM Heap Analysis Tool）命令与jmap搭配使用，来分析jmap生成的堆转储快照。运行完毕后通过http://localhost:7000来访问查看dump内容

buxuesongdeMacBook-Pro:~ buxuesong$ jhat account.dump Reading from account.dump... Dump file created Wed Nov 25 23:37:23 CST 2020 Snapshot read, resolving... Resolving 402521 objects... Chasing references, expect 80 dots................................................................................ Eliminating duplicate references................................................................................ Snapshot resolved. Started HTTP server on port 7000 Server is ready.

jstack（Stack Trace for Java）命令用于生成虚拟机当前时刻的线程快照（一般称为threaddump或者javacore文件）

buxuesongdeMacBook-Pro:~ buxuesong$ jstack -l 1939 2020-11-25 23:47:43 Full thread dump Java HotSpot(TM) 64-Bit Server VM (25.201-b09 mixed mode):"Attach Listener" #34 daemon prio=9 os_prio=31 tid=0x00007fbe7a496800 nid=0x9d03 waiting on condition [0x0000000000000000] java.lang.Thread.State: RUNNABLELocked ownable synchronizers: - None"Druid-ConnectionPool-Destroy-205735257" #33 daemon prio=5 os_prio=31 tid=0x00007fbe77f6f800 nid=0x9f03 waiting on condition [0x0000700012133000] java.lang.Thread.State: TIMED_WAITING (sleeping) at java.lang.Thread.sleep(Native Method) at com.alibaba.druid.pool.DruidDataSource$DestroyConnectionThread.run(DruidDataSource.java:2032)Locked ownable synchronizers: - None"Druid-ConnectionPool-Create-205735257" #32 daemon prio=5 os_prio=31 tid=0x00007fbe77a01800 nid=0xa003 waiting on condition [0x0000700012030000] java.lang.Thread.State: WAITING (parking) at sun.misc.Unsafe.park(Native Method) - parking to wait for<0x00000007aa5174d0> (a java.util.concurrent.locks.AbstractQueuedSynchronizer$ConditionObject) at java.util.concurrent.locks.LockSupport.park(LockSupport.java:175) at java.util.concurrent.locks.AbstractQueuedSynchronizer$ConditionObject.await(AbstractQueuedSynchronizer.java:2039) at com.alibaba.druid.pool.DruidDataSource$CreateConnectionThread.run(DruidDataSource.java:1948)Locked ownable synchronizers: - None"mysql-cj-abandoned-connection-cleanup" #31 daemon prio=5 os_prio=31 tid=0x00007fbe7a3cf000 nid=0x6703 in Object.wait() [0x0000700011f2d000] java.lang.Thread.State: TIMED_WAITING (on object monitor) at java.lang.Object.wait(Native Method) - waiting on <0x0000000797d2a1f0> (a java.lang.ref.ReferenceQueue$Lock) at java.lang.ref.ReferenceQueue.remove(ReferenceQueue.java:144) - locked <0x0000000797d2a1f0> (a java.lang.ref.ReferenceQueue$Lock) at com.mysql.cj.jdbc.AbandonedConnectionCleanupThread.run(AbandonedConnectionCleanupThread.java:85) at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149) at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624) at java.lang.Thread.run(Thread.java:748)Locked ownable synchronizers: - <0x0000000797d2cce0> (a java.util.concurrent.ThreadPoolExecutor$Worker)"DestroyJavaVM" #30 prio=5 os_prio=31 tid=0x00007fbe7c87f800 nid=0x1003 waiting on condition [0x0000000000000000] java.lang.Thread.State: RUNNABLELocked ownable synchronizers: - None