JPicus

Overview

JPicus is an I/O analysis tool that helps you analyze the I/O operations of your Java application. It addresses problems such as leaking file handles (the "Too many open files" exception) and I/O performance. In order to analyze a Java process, you attach the JPicus agent which will then collect data about the I/O operations. At any point in time you can connect to the agent and take a snapshot of this data. Depending on the agent startup options that you provided, you will find information in the snapshot, such as:

• File open/close operations - shows the exact stack trace and point in time when a file was opened and closed.
• Failed/Successful delete operations - same for the delete operations
• I/O operations - shows the type of I/O objet (e.g FileInputStream, FileChannel etc), the amount of data transfered, the time it took, the size of the buffer etc

Building

JPicus uses Apache Ant as a build tool. Its default target dist produces two artifacts:

• jpicus.jar - a javaagent that you have to attach to the java process to be analyzed
• com.sap.tools.jpicus.client.jar - a client API that can be used to connect to and control the running agent

Usage

1. Enable the agent.

java -javaagent:/home/pavel/jpicus.jar -jar myapp.jar

2. Connect to the agent, take a snapshot and analyze it:

Connection con  = JPicus.connect(host);
Snapshot s = con.getSnapshot();

Map<String, Set<HandleDescriptor>> handles = s.getHandles();
System.out.println(handles);

Map<String, Set<DeleteOperation>> deleteOperations = s.getDeleteOperations();
System.out.println(deleteOperations);

GUI

JPicus does not have a GUI yet. The closed source version of JPicus had an Eclipse based UI, but decided to drop it in favor of a web based UI. We believe that this will make JPicus easier to deploy and will also lower our maintenance efforts.

JVM compatibility

Current version of JPicus shall work fine with OpenJDK/OracleJVM versions 5 and 6. Version 7 is still not supported, but is on our list.

Contributing

File an issue or send us a pull request.