Preemptive Mode for Web Processes is a new feature of 4D v17. Before enabling this feature it is important to understand the context of where it can be used and, more importantly, the steps necessary for enabling it.

This feature can only be used in the following context:

• The 64 bit version of 4D must be used (this feature is not supported in 32 bit versions of 4D)
• Either 4D Local or 4D Server must be used (this feature is supported in 4D Remote mode)
• The database must be Compiled (this feature is not supported in Interpretred mode)
• The "Use preemptive process" database setting must be enabled (this feature is not enabled by default)
• All web related database methods and project methods must be confirmed by the compiler as thread safe

Given the context listed above, it is important to rememeber that after enabling the "Use preemptive processes" database setting that the database must then be re-compiled so that all of the project methods and database are re-checked for thread-safety. This is an important step and if skipped the database will not be running in compiled mode which means that preemptive mode for web processes would not be used. After using the compiler to check for error, it is important that the developer work through all of the errors listed in order to complete the compilation process.