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The following page has been changed by niq: http://wiki.apache.org/httpd/DoS ------------------------------------------------------------------------------ Raising MaxClients - The main concern when raising MaxClients is memory usage. With the single-threaded Prefork MPM, this is a serios issue, as each client requires its own process, at a marginal cost likely to be significantly in excess of 1Mb RAM, so 1000 slowloris connections will consume gigabytes of RAM. With a threaded MPM such as Worker or Event, each 1Mb memory gives capacity to handle about 10-20 slowloris connections, so a modern server can comfortably accommodate many thousands of clients (though applications may not). Non-Unix MPMs are also threaded, so I would expect them also to work well with high MaxClients settings, but I have no data. + The main concern when raising MaxClients is memory usage. With the single-threaded Prefork MPM, this is a serious issue, as each client requires its own process at a marginal cost likely to be significantly in excess of 1Mb RAM, so 1000 slowloris connections will consume gigabytes of RAM. With a threaded MPM such as Worker or Event, each 1Mb memory gives capacity to handle about 10-20 slowloris connections, so a modern server can comfortably accommodate many thousands of clients (though applications may not). Non-Unix MPMs are also threaded, so I would expect them also to work well with high MaxClients settings, but I have no data. Note that the memory usage reported by tools like ps(1) and top(1) include shared memory, so they report apparent figures that are far higher than apache's actual per-process usage.
