JPS – Java Virtual Machine Process Status tool.
It gives the list of all the instrumented hotspots JVM’s running on the target system. ‘Hotspot’ is an implementation of JVM used across different platforms. This is available since Java 5.0.
All Hadoop processes run on JVM. The Number of JVM depends on our deployment mode:
1) Local (or Standalone) mode: There are no daemons and everything runs on a single JVM.
2) Pseudo-Distributed mode: Each daemon(Namenode, Datanode etc) runs on its own JVM on a single host.
3) Distributed mode: Each Daemon run on its own JVM across a cluster of hosts.