Apache

What is Apache Prefork, Worker and Event MPM (Multi-Processing Modules)

What is Apache Prefork, Worker and Event MPM (Multi-Processing Modules)

The Apache Web Server comes with a Multi-Processing Modules (MPMs) mainly 'prefork' MPM and 'worker' MPM which are responsible for binding to network ports on the machine, accepting requests, and dispatching children to handle the requests.

  1. What is Prefork MPM and worker MPM?
  2. What is a MPM module?
  3. What is the difference between Prefork MPM and Event MPM?
  4. What is Apache MPM event?
  5. How do I know if I have Apache Prefork or worker?
  6. How are MaxRequestWorkers calculated?
  7. Which Apache MPM should I use?
  8. What is ThreadLimit?
  9. What is Mpm_prefork_module?
  10. What is use of MPM in Apache?
  11. What is server limit in Apache?
  12. What is Apache busy?

What is Prefork MPM and worker MPM?

Prefork MPM uses multiple child processes with one thread each and each process handles one connection at a time. Worker MPM uses multiple child processes with many threads each. Each thread handles one connection at a time.

What is a MPM module?

BMW MPM module is responsible for your entertainment, communication, and navigation system. It is responsible for turning ON/OFF your electrical systems and putting them to sleep. Because BMW decided to install it in the trunk, it is a common problem where the MPM module gets wet and shorts out.

What is the difference between Prefork MPM and Event MPM?

Prefork MPM:-

Prefork MPM launches multiple child processes. Each child process handle one connection at a time. Prefork uses high memory in comparison to worker MPM. ... Preform MPM always runs few minimum (MinSpareServers) defined processes as spare, so new requests do not need to wait for new process to start.

What is Apache MPM event?

The event Multi-Processing Module (MPM) is designed to allow more requests to be served simultaneously by passing off some processing work to the listeners threads, freeing up the worker threads to serve new requests.

How do I know if I have Apache Prefork or worker?

Enable Apache mod_info. Query the mod_info url, typically curl localhost/server-info. The "Server Settings" section will show "MPM Name: Worker" Run httpd -V again -- it will still show prefork, not worker.

How are MaxRequestWorkers calculated?

MPM Event: The default ServerLimit value is 16. To increase it, you must also raise MaxRequestWorkers using the following formula: ServerLimit value x 25 = MaxRequestWorkers value. For example, if ServerLimit is set to 20, then MaxRequestWorkers will be 20 x 25 = 500.

Which Apache MPM should I use?

The Event MPM is considered experimental on Apache 2.2 and should only be used with Apache 2.4 or later.

What is ThreadLimit?

ThreadLimit Directive

This directive sets the maximum configured value for ThreadsPerChild for the lifetime of the Apache httpd process. Any attempts to change this directive during a restart will be ignored, but ThreadsPerChild can be modified during a restart up to the value of this directive.

What is Mpm_prefork_module?

These child processes listen for connections and serve them when they arrive. MPM Prefork is self-regulating, so unless you need a much larger overhead, there's very little cause for adjusting it's default configurations. However, you do need to enable this module as it is disabled out of the box.

What is use of MPM in Apache?

Resolution. The Apache Web Server comes with a Multi-Processing Modules (MPMs) mainly 'prefork' MPM and 'worker' MPM which are responsible for binding to network ports on the machine, accepting requests, and dispatching children to handle the requests.

What is server limit in Apache?

On to Apache configuration

By default, Apache comes preconfigured to serve a maximum of 256 clients simultaneously.

What is Apache busy?

Workers that are already processing requests are called busy workers. Depending on the number of idle workers Apache is able to fork or kill processes. Under normal conditions the number of idle workers should be more or less stable thanks to Apache self-regulation.

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