Starting from v16 the 4D Web server has become preemptive to support more simultaneously connected users and speed up their work.

To run the Web server in preemptive mode, check the option Use preemptive processes under Web>Option (I) in the Database Settings.



It is recommended that this option is enabled prior to the compilation process to be sure that any unthread-safe codes are reported during the compilation.

For more information about writing thread-safe code for a preemptive Web process, please refer to the documentation on Using preemptive Web processes

Here is an example of an unthread-safe code detected by the compiler.