The internal web server in Spotfire is used by Worker Host instances (including Automation Services) to serve HTTP content for rendering visualizations during export tasks (e.g., PDF, image). These tasks use headless browsers (Chromium), which require this server to function.

WebServerPortAllocationCount:
Description: Determines how many ports the internal web server binds to. All ports are bound on the loopback interface, localhost. The value for this setting should not be less than the value for ExportRendererCount. If a negative value is specified, this setting defaults to the number of processors on the computer.

ExportRendererCount:
Description: Determines how many renderer processes are used to concurrently render pages for PDF export and other tasks. If a negative value is specified, this setting defaults to the number of processors on the computer.

WebServerPortAllocationCount setting controls how many concurrent export tasks (render to image or PDF) can run per Worker Host.

• Default (-1): Auto-calculates based on processor count.

• On multi-instance setups, this can cause issues due to shared resources.

• Recommendation: Set a fixed value (e.g., 8–16) for more stable performance.

• Tune WebServerPortAllocationCount to match your workload. For high concurrency or shared environments, set a lower, fixed number for better control and export reliability. (Note: This is applicable for powerful machines where you have multiple automation service instances configured on the same machine.)

Key Points:

• One internal web server is created per Worker Host instance.

• ExportRenderer tasks use this server to load and render content via a headless browser.

• If export demand exceeds available ports, tasks are queued.

• Tasks exceeding ExportRenderingTimeout will fail and log an error.

The WebServerPortAllocationCount parameter is crucial for managing how Spotfire handles concurrent export tasks via its internal web server. Understanding and configuring this properly ensures more reliable and efficient export performance, especially in automated or high-concurrency environments.

Doc: Spotfire.Dxp.Worker.Host.exe.config file

• https://docs.tibco.com/pub/spotfire_server/latest/doc/html/TIB_sfire_server_tsas_admin_help/server/topics/spotfire.dxp.worker.host.exe.config_file.html