Multi-process

  

Figure 2: Multi-Process - In the MP model, each server process handles one request at a time. Processes execute the processing stages sequentially.

In the multi-process (MP) architecture, a process is assigned to execute the basic steps associated with serving a client request sequentially. The process performs all the steps related to one HTTP request before it accepts a new request. Since multiple processes are employed (typically 20-200), many HTTP requests can be served concurrently. Overlapping of disk activity, CPU processing and network connectivity occurs naturally, because the operating system switches to a runnable process whenever the currently active process blocks.

Since each process has its own private address space, no synchronization is necessary to handle the processing of different HTTP requests². However, it may be more difficult to perform optimizations in this architecture that rely on global information, such as a shared cache of valid URLs. Figure 2 illustrates the MP architecture.