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OCEE documentation
OCEE documentation


This page describes how the OCEE Accelerator is used and administered.

The normal OpenCms user does not need to care about the Accelerator at all, as it works transparently.

The administrator of the OpenCms instance might need to:

  • Check the current cache usage
  • Adjust the cache settings accordingly

As seen in the configuration page, every cache type in the Accelerator has a fixed size. Depending on the data usage patterns of your OpenCms instance, some of these cache sizes may be too low. The following shows how to check on the cache and see which caches are heavily used (and thus candidates for resizing).

First, click on the Accelerator app from the OpenCms launchpad (note that this requires the root administrator role in OpenCms).


You will get to the accelerator main view, which shows you statistics for the individual accelerator caches, as well as some general Java memory information.


You can view the statistics for the individual accelerator caches here, as well as some general Java memory information.

Initially, this shows the cache statistics for the OpenCms server you are logged into. If you are using the OCEE cluster manager, and want to see the cache statistics for a different server, an additional select box will be shown in the top left that allows you to switch between servers. If you are not using the cluster manager, this select box is not shown.

For each cache instance, the current number of entries as well as cache hits and misses are shown. For cases where it makes sense (the VFS related instances), the online and offline data are shown separately.

The green bars show you how close each cache is to being full (i.e. it shows current number of entries in relation to its capacity).

In general, if you find a cache that is filled to capacity and has a high number of misses, you may want to increase its capacity if you have the memory to spare. To do this, open the cache settings dialog by clicking the gear symbol in the toolbar.


You can adjust the cache capacities in this dialog and click the "OK" button to save them.

Note that these settings can also be changed by editing the ocee-cache.xml configuration file as described in the configuration section, but changing them via the dialog does not require a restart.

In general, the OCEE accelerator cache does not need to be manually updated or cleared. Cache entries are changed or removed when data is changed in OpenCms through the OpenCms API. Specifically for resources or resource-related data, the Online caches are updated when the corresponding resource is published, while the Offline caches are updated when the resource is modified.

In some cases, however, you may want to manually clear the accelerator caches. This is relevant in two situations:

  • You have made some direct modifications to the database without going through the OpenCms API
  • Some internal error in OpenCms prevented a cache from being updated

In these cases, you can just use clear the core caches in the OpenCms workplace, which will also clear the Accelerator caches if OCEE is installed ( Launchpad > Caches > Cache Statistics > Core cache).