- When a user visits a server, does each visitor require a separate httpd process to be running?
- How long is that process running? HTTP is stateless protocol, is the process only running for as long as it takes to render the page?
- Typically (RHEL3) how much memoryy does each httpd process need?
- Is there a way to limit the memory that the process asks for?
Full Version: Apache memory usage
enable server-status (extented) and take a look to the status page... it will explain a lot of things 
1) a user can use more then one single process (like a html page with 50 images: the user (depends on it's browsers settings) can ask (for example) 10 files simultaneously... that mean 10httpd process servicing a single user
)
or another example: ppl that uses download accelerators that simultaneously downloads 4 chunks of the same file from the same server
2) a process will still run till it will serve the number of requests specified in the httpd.conf (like: MaxRequestsPerChild 10000 <= it will regenerate after 10000 requestes)
3) that depends on what you do... in my case with php as module an httpd process that serve static (or nearly static...) content consume around 5~11mb of memory... but if you start using php functions like image manipulation (gd) etc... the memory usage can grow a lot
In my case sometime i see httpd process
4) reduce the number of modules loaded in your httpd.conf and tweak your php pages ?
1) a user can use more then one single process (like a html page with 50 images: the user (depends on it's browsers settings) can ask (for example) 10 files simultaneously... that mean 10httpd process servicing a single user
)
or another example: ppl that uses download accelerators that simultaneously downloads 4 chunks of the same file from the same server
2) a process will still run till it will serve the number of requests specified in the httpd.conf (like: MaxRequestsPerChild 10000 <= it will regenerate after 10000 requestes)
3) that depends on what you do... in my case with php as module an httpd process that serve static (or nearly static...) content consume around 5~11mb of memory... but if you start using php functions like image manipulation (gd) etc... the memory usage can grow a lot
In my case sometime i see httpd process
4) reduce the number of modules loaded in your httpd.conf and tweak your php pages ?
CODE
[admin@titan admin]$ top | grep 'httpd'
29264 apache 16 0 11348 10M 6144 S 8.6 2.1 0:14 0 httpd
30824 apache 15 0 10484 10M 5908 S 2.8 2.0 0:00 0 httpd
30826 apache 15 0 6336 6188 3320 S 2.8 1.2 0:00 0 httpd
30825 apache 15 0 10660 10M 5876 S 1.9 2.0 0:00 0 httpd
30829 apache 15 0 6700 6544 3644 S 1.9 1.2 0:00 0 httpd
30830 apache 15 0 4840 4648 2192 S 0.9 0.9 0:00 0 httpd
29264 apache 16 0 11348 10M 6144 S 11.1 2.1 0:15 0 httpd
30826 apache 15 0 6324 6176 3308 S 2.3 1.2 0:00 0 httpd
30821 apache 15 0 11136 10M 6196 S 1.5 2.1 0:00 0 httpd
30823 apache 15 0 6660 6512 3628 S 1.1 1.2 0:00 0 httpd
30831 apache 15 0 4856 4672 2192 S 1.1 0.9 0:00 0 httpd
30824 apache 15 0 10512 10M 5932 S 0.9 2.0 0:00 0 httpd
30829 apache 15 0 6924 6776 3860 S 0.9 1.3 0:00 0 httpd
30825 apache 15 0 10648 10M 5864 S 0.5 2.0 0:00 0 httpd
30830 apache 15 0 4844 4656 2188 R 0.3 0.9 0:00 0 httpd
29264 apache 16 0 11348 10M 6144 S 9.1 2.1 0:15 0 httpd
30760 apache 15 0 10000 9832 5296 S 5.5 1.9 0:00 0 httpd
30827 apache 15 0 9984 9828 5472 S 4.5 1.9 0:00 0 httpd
30330 apache 16 0 10584 10M 5808 S 1.1 2.0 0:01 0 httpd
30823 apache 15 0 6644 6496 3612 S 0.9 1.2 0:00 0 httpd
30829 apache 15 0 7020 6872 3904 S 0.5 1.3 0:00 0 httpd
30825 apache 15 0 10628 10M 5844 S 0.3 2.0 0:00 0 httpd
30830 apache 15 0 4844 4656 2184 S 0.3 0.9 0:00 0 httpd
30824 apache 16 0 10632 10M 6048 S 0.1 2.0 0:00 0 httpd
29264 apache 15 0 11348 10M 6144 S 8.3 2.1 0:16 0 httpd
30760 apache 16 0 10176 9.8M 5476 S 1.9 1.9 0:00 0 httpd
30829 apache 15 0 7108 6960 3992 S 0.9 1.3 0:00 0 httpd
30825 apache 15 0 10672 10M 5884 R 0.5 2.0 0:00 0 httpd
30830 apache 15 0 6232 6084 3200 S 0.5 1.1 0:00 0 httpd
30771 apache 15 0 10508 9M 5520 S 0.3 2.0 0:00 0 httpd
30331 apache 15 0 11544 11M 6428 D 0.1 2.2 0:02 0 httpd
29264 apache 16 0 11348 10M 6144 S 8.1 2.1 0:16 0 httpd
30825 apache 15 0 10808 10M 6008 S 0.5 2.0 0:00 0 httpd
30829 apache 15 0 7108 6960 3992 S 0.3 1.3 0:00 0 httpd
30830 apache 15 0 6232 6084 3200 S 0.1 1.1 0:00 0 httpd
29264 apache 15 0 11348 10M 6144 R 9.9 2.1 0:17 0 httpd
30773 apache 16 0 10548 10M 5776 S 4.5 2.0 0:01 0 httpd
30820 apache 16 0 10440 10M 5804 S 3.9 2.0 0:00 0 httpd
29046 apache 16 0 11352 10M 6360 S 1.9 2.1 0:03 0 httpd
29264 apache 16 0 11380 10M 6144 R 12.1 2.1 0:17 0 httpd
30773 apache 15 0 10548 10M 5776 S 0.5 2.0 0:01 0 httpd
29912 apache 16 0 12160 11M 6220 R 13.7 2.3 0:03 0 httpd
29264 apache 16 0 11348 10M 6144 S 10.7 2.1 0:18 0 httpd
30766 apache 15 0 6044 5896 3128 S 1.7 1.1 0:00 0 httpd
30773 apache 15 0 10548 10M 5776 S 0.3 2.0 0:01 0 httpd
30820 apache 15 0 10476 10M 5840 S 0.1 2.0 0:00 0 httpd
30827 apache 15 0 9984 9836 5472 S 0.1 1.9 0:00 0 httpd
29264 apache 16 0 11348 10M 6144 S 10.5 2.1 0:18 0 httpd
29912 apache 15 0 11692 11M 6196 S 3.3 2.2 0:03 0 httpd
30773 apache 15 0 10496 10M 5724 S 0.7 2.0 0:01 0 httpd
30828 apache 15 0 10544 10M 5556 S 0.5 2.0 0:00 0 httpd
29978 apache 15 0 10252 9916 5352 S 0.3 1.9 0:02 0 httpd
30332 apache 16 0 9924 9780 4892 S 0.3 1.9 0:01 0 httpd
30403 apache 15 0 10140 9580 5172 S 0.3 1.8 0:01 0 httpd
30766 apache 15 0 6008 5860 3088 S 0.1 1.1 0:00 0 httpd
28970 apache 16 0 17456 16M 6764 S 6.3 3.3 1:05 0 httpd
30689 apache 16 0 8928 8752 5288 S 1.9 1.7 0:00 0 httpd
29264 apache 16 0 11364 10M 6160 S 1.3 2.1 0:18 0 httpd
29912 apache 15 0 11736 11M 6240 S 0.9 2.2 0:03 0 httpd
29978 apache 15 0 10252 9916 5352 S 0.5 1.9 0:02 0 httpd
28970 apache 16 0 17456 16M 6764 S 9.7 3.3 1:05 0 httpd
29912 apache 15 0 11736 11M 6240 S 0.5 2.2 0:03 0 httpd
29978 apache 15 0 10252 9916 5352 S 0.3 1.9 0:02 0 httpd
30768 apache 15 0 0 0 0 Z 0.1 0.0 0:00 0 httpd <defunct>
28970 apache 16 0 17484 16M 6792 S 11.0 3.3 1:06 0 httpd
29978 apache 16 0 10564 9M 5664 S 5.7 2.0 0:02 0 httpd
30764 apache 16 0 10584 10M 5740 S 5.3 2.0 0:00 0 httpd
30816 apache 15 0 10236 9.8M 5668 S 3.9 1.9 0:00 0 httpd
30769 apache 16 0 8692 8544 5140 R 1.7 1.6 0:00 0 httpd
29912 apache 15 0 11736 11M 6240 S 0.5 2.2 0:03 0 httpd
28970 apache 16 0 17484 16M 6792 S 12.5 3.3 1:06 0 httpd
29919 apache 15 0 16356 15M 6272 R 0.5 3.1 1:00 0 httpd
30769 apache 16 0 8888 8740 5208 S 0.5 1.7 0:00 0 httpd
30410 apache 15 0 10476 10M 5596 S 0.3 2.0 0:01 0 httpd
30820 apache 15 0 10448 10M 5812 S 0.3 2.0 0:00 0 httpd
28970 apache 16 0 17484 16M 6792 S 11.1 3.3 1:07 0 httpd
29919 apache 16 0 16608 15M 6396 S 8.3 3.1 1:01 0 httpd
28976 apache 16 0 11436 10M 6012 S 6.9 2.1 0:03 0 httpd
30820 apache 15 0 10448 10M 5812 S 0.5 2.0 0:00 0 httpd
30410 apache 15 0 10476 10M 5596 S 0.1 2.0 0:01 0 httpd
29264 apache 16 0 11348 10M 6144 S 8.6 2.1 0:14 0 httpd
30824 apache 15 0 10484 10M 5908 S 2.8 2.0 0:00 0 httpd
30826 apache 15 0 6336 6188 3320 S 2.8 1.2 0:00 0 httpd
30825 apache 15 0 10660 10M 5876 S 1.9 2.0 0:00 0 httpd
30829 apache 15 0 6700 6544 3644 S 1.9 1.2 0:00 0 httpd
30830 apache 15 0 4840 4648 2192 S 0.9 0.9 0:00 0 httpd
29264 apache 16 0 11348 10M 6144 S 11.1 2.1 0:15 0 httpd
30826 apache 15 0 6324 6176 3308 S 2.3 1.2 0:00 0 httpd
30821 apache 15 0 11136 10M 6196 S 1.5 2.1 0:00 0 httpd
30823 apache 15 0 6660 6512 3628 S 1.1 1.2 0:00 0 httpd
30831 apache 15 0 4856 4672 2192 S 1.1 0.9 0:00 0 httpd
30824 apache 15 0 10512 10M 5932 S 0.9 2.0 0:00 0 httpd
30829 apache 15 0 6924 6776 3860 S 0.9 1.3 0:00 0 httpd
30825 apache 15 0 10648 10M 5864 S 0.5 2.0 0:00 0 httpd
30830 apache 15 0 4844 4656 2188 R 0.3 0.9 0:00 0 httpd
29264 apache 16 0 11348 10M 6144 S 9.1 2.1 0:15 0 httpd
30760 apache 15 0 10000 9832 5296 S 5.5 1.9 0:00 0 httpd
30827 apache 15 0 9984 9828 5472 S 4.5 1.9 0:00 0 httpd
30330 apache 16 0 10584 10M 5808 S 1.1 2.0 0:01 0 httpd
30823 apache 15 0 6644 6496 3612 S 0.9 1.2 0:00 0 httpd
30829 apache 15 0 7020 6872 3904 S 0.5 1.3 0:00 0 httpd
30825 apache 15 0 10628 10M 5844 S 0.3 2.0 0:00 0 httpd
30830 apache 15 0 4844 4656 2184 S 0.3 0.9 0:00 0 httpd
30824 apache 16 0 10632 10M 6048 S 0.1 2.0 0:00 0 httpd
29264 apache 15 0 11348 10M 6144 S 8.3 2.1 0:16 0 httpd
30760 apache 16 0 10176 9.8M 5476 S 1.9 1.9 0:00 0 httpd
30829 apache 15 0 7108 6960 3992 S 0.9 1.3 0:00 0 httpd
30825 apache 15 0 10672 10M 5884 R 0.5 2.0 0:00 0 httpd
30830 apache 15 0 6232 6084 3200 S 0.5 1.1 0:00 0 httpd
30771 apache 15 0 10508 9M 5520 S 0.3 2.0 0:00 0 httpd
30331 apache 15 0 11544 11M 6428 D 0.1 2.2 0:02 0 httpd
29264 apache 16 0 11348 10M 6144 S 8.1 2.1 0:16 0 httpd
30825 apache 15 0 10808 10M 6008 S 0.5 2.0 0:00 0 httpd
30829 apache 15 0 7108 6960 3992 S 0.3 1.3 0:00 0 httpd
30830 apache 15 0 6232 6084 3200 S 0.1 1.1 0:00 0 httpd
29264 apache 15 0 11348 10M 6144 R 9.9 2.1 0:17 0 httpd
30773 apache 16 0 10548 10M 5776 S 4.5 2.0 0:01 0 httpd
30820 apache 16 0 10440 10M 5804 S 3.9 2.0 0:00 0 httpd
29046 apache 16 0 11352 10M 6360 S 1.9 2.1 0:03 0 httpd
29264 apache 16 0 11380 10M 6144 R 12.1 2.1 0:17 0 httpd
30773 apache 15 0 10548 10M 5776 S 0.5 2.0 0:01 0 httpd
29912 apache 16 0 12160 11M 6220 R 13.7 2.3 0:03 0 httpd
29264 apache 16 0 11348 10M 6144 S 10.7 2.1 0:18 0 httpd
30766 apache 15 0 6044 5896 3128 S 1.7 1.1 0:00 0 httpd
30773 apache 15 0 10548 10M 5776 S 0.3 2.0 0:01 0 httpd
30820 apache 15 0 10476 10M 5840 S 0.1 2.0 0:00 0 httpd
30827 apache 15 0 9984 9836 5472 S 0.1 1.9 0:00 0 httpd
29264 apache 16 0 11348 10M 6144 S 10.5 2.1 0:18 0 httpd
29912 apache 15 0 11692 11M 6196 S 3.3 2.2 0:03 0 httpd
30773 apache 15 0 10496 10M 5724 S 0.7 2.0 0:01 0 httpd
30828 apache 15 0 10544 10M 5556 S 0.5 2.0 0:00 0 httpd
29978 apache 15 0 10252 9916 5352 S 0.3 1.9 0:02 0 httpd
30332 apache 16 0 9924 9780 4892 S 0.3 1.9 0:01 0 httpd
30403 apache 15 0 10140 9580 5172 S 0.3 1.8 0:01 0 httpd
30766 apache 15 0 6008 5860 3088 S 0.1 1.1 0:00 0 httpd
28970 apache 16 0 17456 16M 6764 S 6.3 3.3 1:05 0 httpd
30689 apache 16 0 8928 8752 5288 S 1.9 1.7 0:00 0 httpd
29264 apache 16 0 11364 10M 6160 S 1.3 2.1 0:18 0 httpd
29912 apache 15 0 11736 11M 6240 S 0.9 2.2 0:03 0 httpd
29978 apache 15 0 10252 9916 5352 S 0.5 1.9 0:02 0 httpd
28970 apache 16 0 17456 16M 6764 S 9.7 3.3 1:05 0 httpd
29912 apache 15 0 11736 11M 6240 S 0.5 2.2 0:03 0 httpd
29978 apache 15 0 10252 9916 5352 S 0.3 1.9 0:02 0 httpd
30768 apache 15 0 0 0 0 Z 0.1 0.0 0:00 0 httpd <defunct>
28970 apache 16 0 17484 16M 6792 S 11.0 3.3 1:06 0 httpd
29978 apache 16 0 10564 9M 5664 S 5.7 2.0 0:02 0 httpd
30764 apache 16 0 10584 10M 5740 S 5.3 2.0 0:00 0 httpd
30816 apache 15 0 10236 9.8M 5668 S 3.9 1.9 0:00 0 httpd
30769 apache 16 0 8692 8544 5140 R 1.7 1.6 0:00 0 httpd
29912 apache 15 0 11736 11M 6240 S 0.5 2.2 0:03 0 httpd
28970 apache 16 0 17484 16M 6792 S 12.5 3.3 1:06 0 httpd
29919 apache 15 0 16356 15M 6272 R 0.5 3.1 1:00 0 httpd
30769 apache 16 0 8888 8740 5208 S 0.5 1.7 0:00 0 httpd
30410 apache 15 0 10476 10M 5596 S 0.3 2.0 0:01 0 httpd
30820 apache 15 0 10448 10M 5812 S 0.3 2.0 0:00 0 httpd
28970 apache 16 0 17484 16M 6792 S 11.1 3.3 1:07 0 httpd
29919 apache 16 0 16608 15M 6396 S 8.3 3.1 1:01 0 httpd
28976 apache 16 0 11436 10M 6012 S 6.9 2.1 0:03 0 httpd
30820 apache 15 0 10448 10M 5812 S 0.5 2.0 0:00 0 httpd
30410 apache 15 0 10476 10M 5596 S 0.1 2.0 0:01 0 httpd
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