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| <h1 align="CENTER">Server Pool Management</h1> |
| <hr /> |
| |
| <p>We found that many people were using values for "MaxServers" |
| either too high or too low, and were hanging themselves on it. |
| The model we adopted is still based on long-lived |
| minimal-forking processes, but instead of specifying one number |
| of persistent processes, the web-master specifies a maximum and |
| minimum number of processes to be "spare" - every couple of |
| seconds the parent checks the actual number of spare servers |
| and adjusts accordingly. This should keep the number of servers |
| concurrently running relatively low while still ensuring |
| minimal forking.</p> |
| |
| <p>We renamed the current StartServers to MinSpareServers, |
| created separate StartServers parameter which means what it |
| says, and renamed MaxServers to MaxSpareServers (though the old |
| name still works, for NCSA 1.4 back-compatibility). The old |
| names were generally regarded as too confusing.</p> |
| |
| <p>The defaults for each variable are:</p> |
| <pre> |
| MinSpareServers 5 |
| MaxSpareServers 10 |
| StartServers 5 |
| </pre> |
| There is an absolute maximum number of simultaneous children |
| defined by a compile-time limit which defaults to 256 and a |
| "MaxClients" directive which specifies the number of |
| simultaneous children that will be allowed. MaxClients can be |
| adjusted up to the compile-time limit (HARD_SERVER_LIMIT, |
| defined in httpd.h). If you need more than 256 simultaneous |
| children, you need to modify both HARD_SERVER_LIMIT and |
| MaxClients. |
| |
| <p>In versions before 1.2, HARD_SERVER_LIMIT defaulted to |
| 150.</p> |
| |
| <p>We do not recommend changing either of these values |
| unless:</p> |
| |
| <ol> |
| <li>You know you have the server resources to handle |
| more</li> |
| |
| <li>You use the machine for other purposes and must limit the |
| amount of memory Apache uses</li> |
| </ol> |
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