Specify the number of HTML renderers to remain active and available for reuse in a form component containing many HTML widgets.

CefRendererCache = Number

Default value: 20
File section: [upi]


Number—number of rendering engines to remain active. A negative number or 0 disables the cache of renderers and makes HTML widgets much slower.


This setting is applicable to Uniface desktop applications that contain one or more form components with at least one HTML widget. By default, it is set to 20 to improve HTML widget performance, especially in forms that contain many HTML widget instances, and in forms that are typically started and closed many times during the application session.

The first time a form containing HTML widgets is started, it may take some time to render. However, subsequent performance will be much better, as the application re-uses the cached renderers.

Effect of the Setting

The HTML widget makes use of HTML rendering and JavaScript execution provided by the Chromium Embedded Framework (CEF3). For every HTML field in a Uniface application, a Chromium rendering engine (cefrenderer.exe) is started as a new process.

When a form contains many HTML widgets, the performance of the component can suffer because of the number of renderers that must be started. To improve performance, you can specify a higher number of renders that can stay active and be reused.

A higher value reserves memory for reuse and makes the rendering engine startup time faster. It does not reserve the memory up front; it just means that it is not freed after closing rendering engines.

A lower value frees up memory for other purposes, but slows the rendering engine startup time. It does not limit the number of rendering engines running at the same time; it just frees up the memory after closing them.

Depending on the amount of memory available to the application, we recommend that you set the value as high as the total number of rendering engines running at the same time.

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