简介：
jps(Java Virtual Machine Process Status Tool)是JDK提供的一个显示当前所有java进程pid的命令，简单实用，非常适合在linux/unix平台上简单察看当前java进程的一些简单情况。 使用它前是jdk安装正确，环境变量设置正确。由于jps是一个工具使用的非常广泛，所以jdk设置的PATH最好是全局变量，这样所有的用户都可以使用。用法：
man jps
[root@hd1 ~]# man jpsjps(1) Monitoring Tools jps(1)NAME jps - Lists the instrumented Java Virtual Machines (JVMs) on the target system. This command is experimental and unsupported.SYNOPSIS jps [ options ] [ hostid ] options Command-line options. See Options. hostid The identifier of the host for which the process report should be generated. The hostid can include optional components that indicate the communications protocol, port number, and other implementation specific data. See Host Identifier.DESCRIPTION The jps command lists the instrumented Java HotSpot VMs on the target system. The command is limited to reporting information on JVMs for which it has the access permissions. If the jps command is run without specifying a hostid, then it searches for instrumented JVMs on the local host. If started with a hostid, then it searches for JVMs on the indicated host, using the specified protocol and port. A jstatd process is assumed to be running on the target host. The jps command reports the local JVM identifier, or lvmid, for each instrumented JVM found on the target system. The lvmid is typically, but not necessarily, the operating system’s process identifier for the JVM process. With no options, jps lists each Java application’s lvmid followed by the short form of the application’s class name or jar file name. The short form of the class name or JAR file name omits the class’s package information or the JAR files path information. The jps command uses the Java launcher to find the class name and arguments passed to the main method. If the target JVM is started with a custom launcher, then the class or JAR file name and the arguments to the main method are not available. In this case, the jps command outputs the string Unknown for the class name or JAR file name and for the arguments to the main method. The list of JVMs produced by the jps command can be limited by the permissions granted to the principal running the command. The command only lists the JVMs for which the principle has access rights as determined by operating system-specific access control mechanisms.OPTIONS The jps command supports a number of options that modify the output of the command. These options are subject to change or removal in the future. -q Suppresses the output of the class name, JAR file name, and arguments passed to the main method, producing only a list of local JVM identifiers. -m Displays the arguments passed to the main method. The output may be null for embedded JVMs. -l Displays the full package name for the application’s main class or the full path name to the application’s JAR file. -v Displays the arguments passed to the JVM. -V Suppresses the output of the class name, JAR file name, and arguments passed to the main method, producing only a list of local JVM identifiers. -Joption Passes option to the JVM, where option is one of the options described on the reference page for the Java application launcher. For example, -J-Xms48m sets the startup memory to 48 MB. See java(1).HOST IDENTIFIER The host identifier, or hostid is a string that indicates the target system. The syntax of the hostid string corresponds to the syntax of a URI: [protocol:][[//]hostname][:port][/servername] protocol The communications protocol. If the protocol is omitted and a hostname is not specified, then the default protocol is a platform-specific, optimized, local protocol. If the protocol is omitted and a host name is specified, then the default protocol is rmi. hostname A hostname or IP address that indicates the target host. If you omit the hostname parameter, then the target host is the local host. port The default port for communicating with the remote server. If the hostname parameter is omitted or the protocol parameter specifies an optimized, local protocol, then the port parameter is ignored. Otherwise, treatment of the port parameter is implementation specific. For the default rmi protocol, the port parameter indicates the port number for the rmiregistry on the remote host. If the port parameter is omitted, and the protocol parameter indicates rmi, then the default rmiregistry port (1099) is used. servername The treatment of this parameter depends on the implementation. For the optimized, local protocol, this field is ignored. For the rmi protocol, this parameter is a string that represents the name of the RMI remote object on the remote host. See the jstatd command -noption for more information.OUTPUT FORMAT The output of the jps command follows the following pattern: lvmid [ [ classname | JARfilename | "Unknown"] [ arg* ] [ jvmarg* ] ] All output tokens are separated by white space. An arg value that includes embedded white space introduces ambiguity when attempting to map arguments to their actual positional parameters. Note: It is recommended that you do not write scripts to parse jps output because the format might change in future releases. If you write scripts that parse jps output, then expect to modify them for future releases of this tool.EXAMPLES This section provides examples of the jps command. List the instrumented JVMs on the local host: jps 18027 Java2Demo.JAR 18032 jps 18005 jstat The following example lists the instrumented JVMs on a remote host. This example assumes that the jstat server and either the its internal RMI registry or a separate external rmiregistry process are running on the remote host on the default port (port 1099). It also assumes that the local host has appropriate permissions to access the remote host. This example also includes the -l option to output the long form of the class names or JAR file names. jps -l remote.domain 3002 /opt/jdk1.7.0/demo/jfc/Java2D/Java2Demo.JAR 2857 sun.tools.jstatd.jstatd The following example lists the instrumented JVMs on a remote host with a non-default port for the RMI registry. This example assumes that the jstatd server, with an internal RMI registry bound to port 2002, is running on the remote host. This example also uses the -m option to include the arguments passed to the main method of each of the listed Java applications. jps -m remote.domain:2002 3002 /opt/jdk1.7.0/demo/jfc/Java2D/Java2Demo.JAR 3102 sun.tools.jstatd.jstatd -p 2002SEE ALSO · java(1) · jstat(1) · jstatd(1) · rmiregistry(1)
从以上可知：jps -vV -m -l -q 几个选项，格式 jps [ options ] [ hostid ]
[hadoop@hd1 sbin]$ jps2278 ResourceManager2120 SecondaryNameNode2538 Jps1919 NameNode
[hadoop@hd1 sbin]$ jps -q2560227821201919
[hadoop@hd1 sbin]$ jps -m2595 Jps -m2278 ResourceManager2120 SecondaryNameNode1919 NameNode
[hadoop@hd1 sbin]$ jps -l2278 org.apache.hadoop.yarn.server.resourcemanager.ResourceManager2120 org.apache.hadoop.hdfs.server.namenode.SecondaryNameNode1919 org.apache.hadoop.hdfs.server.namenode.NameNode2607 sun.tools.jps.Jps
hadoop@hd1 sbin]$ jps -v2278 ResourceManager -Dproc_resourcemanager -Xmx1000m -Dhadoop.log.dir=/usr/hadoop/hadoop-2.7.1/logs -Dyarn.log.dir=/usr/hadoop/hadoop-2.7.1/logs -Dhadoop.log.file=yarn-hadoop-resourcemanager-hd1.log -Dyarn.log.file=yarn-hadoop-resourcemanager-hd1.log -Dyarn.home.dir= -Dyarn.id.str=hadoop -Dhadoop.root.logger=INFO,RFA -Dyarn.root.logger=INFO,RFA -Djava.library.path=/usr/hadoop/hadoop-2.7.1/lib/native -Dyarn.policy.file=hadoop-policy.xml -Dhadoop.log.dir=/usr/hadoop/hadoop-2.7.1/logs -Dyarn.log.dir=/usr/hadoop/hadoop-2.7.1/logs -Dhadoop.log.file=yarn-hadoop-resourcemanager-hd1.log -Dyarn.log.file=yarn-hadoop-resourcemanager-hd1.log -Dyarn.home.dir=/usr/hadoop/hadoop-2.7.1 -Dhadoop.home.dir=/usr/hadoop/hadoop-2.7.1 -Dhadoop.root.logger=INFO,RFA -Dyarn.root.logger=INFO,RFA -Djava.library.path=/usr/hadoop/hadoop-2.7.1/lib/native2120 SecondaryNameNode -Dproc_secondarynamenode -Xmx1000m -Djava.net.preferIPv4Stack=true -Dhadoop.log.dir=/usr/hadoop/hadoop-2.7.1/logs -Dhadoop.log.file=hadoop.log -Dhadoop.home.dir=/usr/hadoop/hadoop-2.7.1 -Dhadoop.id.str=hadoop -Dhadoop.root.logger=INFO,console -Djava.library.path=/usr/hadoop/hadoop-2.7.1/lib/native -Dhadoop.policy.file=hadoop-policy.xml -Djava.net.preferIPv4Stack=true -Djava.net.preferIPv4Stack=true -Djava.net.preferIPv4Stack=true -Dhadoop.log.dir=/usr/hadoop/hadoop-2.7.1/logs -Dhadoop.log.file=hadoop-hadoop-secondarynamenode-hd1.log -Dhadoop.home.dir=/usr/hadoop/hadoop-2.7.1 -Dhadoop.id.str=hadoop -Dhadoop.root.logger=INFO,RFA -Djava.library.path=/usr/hadoop/hadoop-2.7.1/lib/native -Dhadoop.policy.file=hadoop-policy.xml -Djava.net.preferIPv4Stack=true -Dhadoop.security.logger=INFO,RFAS -Dhdfs.audit.logger=INFO,NullAppender -Dhadoop.security.logger=INFO,RFAS -Dhdfs.audit.logger=INFO,NullAppender -Dhadoop.security.logger=INFO,RFAS -Dhdfs.audit.logger=INFO,NullAppender -Dhadoop.security.logger=INFO,RFAS2617 Jps -Denv.class.path=.:.::/usr/java/jdk1.8.0_11/lib:/usr/java/jdk1.8.0_11/jre/lib:/usr/java/jdk1.8.0_11/lib:/usr/java/jdk1.8.0_11/jre/lib -Dapplication.home=/usr/java/jdk1.8.0_11 -Xms8m1919 NameNode -Dproc_namenode -Xmx1000m -Djava.net.preferIPv4Stack=true -Dhadoop.log.dir=/usr/hadoop/hadoop-2.7.1/logs -Dhadoop.log.file=hadoop.log -Dhadoop.home.dir=/usr/hadoop/hadoop-2.7.1 -Dhadoop.id.str=hadoop -Dhadoop.root.logger=INFO,console -Djava.library.path=/usr/hadoop/hadoop-2.7.1/lib/native -Dhadoop.policy.file=hadoop-policy.xml -Djava.net.preferIPv4Stack=true -Djava.net.preferIPv4Stack=true -Djava.net.preferIPv4Stack=true -Dhadoop.log.dir=/usr/hadoop/hadoop-2.7.1/logs -Dhadoop.log.file=hadoop-hadoop-namenode-hd1.log -Dhadoop.home.dir=/usr/hadoop/hadoop-2.7.1 -Dhadoop.id.str=hadoop -Dhadoop.root.logger=INFO,RFA -Djava.library.path=/usr/hadoop/hadoop-2.7.1/lib/native -Dhadoop.policy.file=hadoop-policy.xml -Djava.net.preferIPv4Stack=true -Dhadoop.security.logger=INFO,RFAS -Dhdfs.audit.logger=INFO,NullAppender -Dhadoop.security.logger=INFO,RFAS -Dhdfs.audit.logger=INFO,NullAppender -Dhadoop.security.logger=INFO,RFAS -Dhdfs.audit.logger=INFO,NullAppender -Dhadoop.security.logger=INFO,RFAS
[hadoop@hd1 sbin]$ jps -V2627 Jps2278 ResourceManager2120 SecondaryNameNode1919 NameNode
这个hostid 很有用，可以查看远程主机的进程状态，不过前提是需要开放一个jvm端口，[protocol:][[//]hostname][:port][/servername]
生产环境jps 报错process information unavailable处理流程
- 1.jps找到各个进程号
- 2.ps -ef|grep pid是否存在（这步很关键要做判断查看进程是否存在）
- 3.假如进程不存在，我们可以去该/tmp/hsperfdata_xxx去删除
- 4.如果存在千万别删，自己查看是不可以的，切换到启动HDFS进程的用户下(一般是hadoop用户) 再用jps即显示正常。