Saving Live Sessions to Disk

## Saving Live Sessions to Disk |

| Snapshots of live profiling sessions can be saved to disk by selecting Session->Save snapshot from JProfiler's main menu or by clicking on the corresponding tool bar entry in JProfiler's main tool bar. A file chooser will be brought up where you can select the name and directory of the snapshot file to be written. The standard extension of JProfiler's snapshot files is `*.jps`. Once JProfiler has finished writing the snapshot to disk, a message box informs you that the snapshot was saved. A bookmarks will be added when a snapshot is saved manually.

| Besides JProfiler snapshots, JProfiler can also save and open HPROF heap dump files with the Profiler->Save HPROF snapshot. You will be asked to provide a file name for the HPROF snapshot. The snapshot file will be given an .hprof extension and will be saved on the computer where the profiled JVM is running. The path will be interpreted as relative to the current directory of the profiled JVM. In situations where physical memory is sparse, saving an HPROF snapshot can be preferable compared to saving a full JProfiler snapshot. Also, there are alternative ways to save HPROF snapshots: with -XX:+HeapDumpOnOutOfMemoryError The -XX:+HeapDumpOnOutOfMemoryError VM parameter is supported by Sun 1.4.2_12+, 1.5.0_07+ and 1.6+ JVMs and is the basis of the "Out of memory exception" trigger type. with jmap The jmap executable in the JDK can be used to extract an HPROF heap dump from a running JVM. It is partially supported by Sun 1.5 JVMs and supported by all Sun 1.6 JVMs. with jconsole The jconsole executable in the JDK can be used to extract an HPROF heap dump from a running JVM. It is available for Java 1.5+. Starting with Java 1.6 you can attach to any local Java process without any modifications, for Java 1.5, some modifications of the VM parameters are required.

| You can also save snapshots with the offline profiling API or use a trigger and the "Save snapshot" and "Create a HPROF heapdump" actions to save snapshot in an exact way. This is also useful for offline profiling.

| Saved snapshots can be loaded by selecting Session->Open snapshot from JProfiler's main menu. by selecting a file from the "Open snapshot" tab in JProfiler's start center. The following restrictions apply when viewing snapshots: JProfiler snapshots After a JProfiler snapshot has been loaded, the functionality of all views is identical to a live profiling session with the exception of the heap walker view: The heap walker overview will be shown if a heap snapshot was taken at the time of saving, otherwise the heap walker will be unavailable. HPROF snapshots When an HPROF snapshot is loaded, only the heap walker is available. Also, the "Allocations" and "Time" views of the heap walker are not available. The status bar indicates that a snapshot is being viewed by displaying the message Snapshot in its rightmost compartment.