The Diagnostics Collector produces an output file for each problem event that occurs in your Java™ application.
When you add the command-line option -Xdiagnosticscollector, the Diagnostics Collector runs and produces several output .zip files. One file is produced at startup. Another file is produced for each dump event that occurs during the lifetime of the JVM. For each problem event that occurs in your Java application, one .zip file is created to hold all the diagnostics for that event. For example, an application might have multiple OutOfMemoryErrors but keep on running. Diagnostics Collector produces multiple .zip files, each holding the diagnostics from one OutOfMemoryError.
java.<event>.<YYYYMMDD.hhmmss.pid>.zipIn this file name, <event> is one of the following names:
<YYYYMMDD.hhmmss.pid> is a combination of the time stamp of the dump event, and the process ID for the original Java application. pid is not the process ID for the Diagnostics Collector.
The Diagnostics Collector copies files that it writes to the output .zip file. It does not delete the original diagnostics information.
When the Diagnostics Collector finds a system dump for the problem event, then by default it runs jextract to post-process the dump and gather context information This information enables later debugging. Diagnostics Collector automates a manual step that is requested by IBM® support on most platforms. You can prevent Diagnostics Collector from running jextract by setting the property run.jextract to false in the settings file. For more information, see Diagnostics Collector settings.
The Diagnostics Collector logs its actions and messages in a file named JavaDiagnosticsCollector.<number>.log. The log file is written to the current working directory. The log file is also stored in the output .zip file. The <number> component in the log file name is not significant; it is added to keep the log file names unique.
The Diagnostics Collector is a Java VM dump agent. It is run by the Java VM in response to the dump events that produce diagnostic files by default. It runs in a new Java process, using the same version of Java as the VM producing dumps. This ensures that the tool runs the correct version of jextract for any system dumps produced by the original Java process.