How do you increase the max number of concurrent connections in Apache

Question

What httpd conf settings do I need to change to increase the max number of concurrent connections for Apache  NOTE  I turned off KeepAlive since this is mainly an API server       KeepAlive  Whether or not to allow persistent connections  more than   one request per connection   Set to  Off  to deactivate    KeepAlive Off      MaxKeepAliveRequests  The maximum number of requests to allow   during a persistent connection  Set to 0 to allow an unlimited amount    We recommend you leave this number high  for maximum performance    MaxKeepAliveRequests 100      KeepAliveTimeout  Number of seconds to wait for the next request from the   same client on the same connection    KeepAliveTimeout 15        Server-Pool Size Regulation  MPM specific         prefork MPM   StartServers  number of server processes to start   MinSpareServers  minimum number of server processes which are kept spare   MaxSpareServers  maximum number of server processes which are kept spare   ServerLimit  maximum value for MaxClients for the lifetime of the server   MaxClients  maximum number of server processes allowed to start   MaxRequestsPerChild  maximum number of requests a server process serves  lt IfModule prefork c gt  StartServers       8 MinSpareServers    5 MaxSpareServers   20 ServerLimit      256 MaxClients       256 MaxRequestsPerChild  4000  lt  IfModule gt     worker MPM   StartServers  initial number of server processes to start   MaxClients  maximum number of simultaneous client connections   MinSpareThreads  minimum number of worker threads which are kept spare   MaxSpareThreads  maximum number of worker threads which are kept spare   ThreadsPerChild  constant number of worker threads in each server process   MaxRequestsPerChild  maximum number of requests a server process serves  lt IfModule worker c gt  StartServers         2 MaxClients         150 MinSpareThreads     25 MaxSpareThreads     75  ThreadsPerChild     25 MaxRequestsPerChild  0  lt  IfModule gt

User · Answer

change the MaxClients directive  it is now on 256

User · Answer

Here s a detailed explanation about the calculation of MaxClients and MaxRequestsPerChild  http   web archive org web 20160415001028 http   www genericarticles com mediawiki index php title How to optimize apache web server for maximum concurrent connections or increase max clients in apache  ServerLimit 16 StartServers 2 MaxClients 200 MinSpareThreads 25 MaxSpareThreads 75 ThreadsPerChild 25   First of all  whenever an apache is started  it will start 2 child processes which is determined by StartServers parameter  Then each process will start 25 threads determined by ThreadsPerChild parameter so this means 2 process can service only 50 concurrent connections clients i e  25x2 50  Now if more concurrent users comes  then another child process will start  that can service another 25 users  But how many child processes can be started is controlled by ServerLimit parameter  this means that in the configuration above  I can have 16 child processes in total  with each child process can handle 25 thread  in total handling 16x25 400 concurrent users  But if number defined in MaxClients is less which is 200 here  then this means that after 8 child processes  no extra process will start since we have defined an upper cap of MaxClients  This also means that if I set MaxClients to 1000  after 16 child processes and 400 connections  no extra process will start and we cannot service more than 400 concurrent clients even if we have increase the MaxClient parameter  In this case  we need to also increase ServerLimit to 1000 25 i e  MaxClients ThreadsPerChild 40 So this is the optmized configuration to server 1000 clients   lt IfModule mpm worker module gt      ServerLimit          40     StartServers          2     MaxClients          1000     MinSpareThreads      25     MaxSpareThreads      75      ThreadsPerChild      25     MaxRequestsPerChild   0  lt  IfModule gt

[apache] How do you increase the max number of concurrent connections in Apache?

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