9.1

What is the main reason why servlets give better performance than programs that use the common gateway interface (CGI), even though Java programs generally run slower than C or C++ programs?

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The CGI interface starts a new process to service each request, which has a significat operating system overhead. On the other hand, servlets are run as threads of an existing process, avoiding this overhead. Further, the process running threads could be the web server process itself, avoiding interprocess communication, which can be expensive. Thus, for small to moderate-sized tasks, the overhead of Java is less than the overhead saved by avoiding process creation and communication.

For tasks involving a lot of CPU activity, this may not be the case, and using CGI with a C or C++ program may give better performance.