The list of modules is different. I don't think you can compare event and prefork servers as if they should behave the same, even more if you have a different list of modules. Consider in prefork each process is a worker, while on event processes are not workers, but threads of each process.
In order to compare fairly you have to use the same modules, same load, similar resulting mpm settings and compare the total usage, still your biggest concern unless you have a faulty module mostly will be CPU. Also consider there are some different modules in each case too, some are third party modules. El lun, 17 may 2021 a las 13:34, Marc Serra (<mse...@manxa.com>) escribió: > Hi to all, > > I already posted this question to stackoverflow.com but no answer after 9 > days: > https://stackoverflow.com/questions/67439771/why-so-much-difference-in-memory-used-per-process-in-apache2-between-two-differe > > I hope the apache gurus in this list can help me :) > > I have a pair of Ubuntu dedicated servers... > > Server1: > Ubuntu 16.04.7 (64 bits) > 16GB RAM > 8 Xeon CPU > Apache 2.4.18 > MPM mode: prefork > > Server2: > Ubuntu server 20.04.2 (64 bits) > 32GB RAM > 8 Xeon CPU > 2.4.41 > MPM mode: event > > On Server1, each apache2 process uses between 7MB and 18MB of RAM ... > # ps axo 'user rss cmd' | grep apache | grep -v "\(root\|grep\|tomcat\)" > www-data 18232 /usr/sbin/apache2 -k start > www-data 11700 /usr/sbin/apache2 -k start > www-data 11276 /usr/sbin/apache2 -k start > www-data 10792 /usr/sbin/apache2 -k start > www-data 11216 /usr/sbin/apache2 -k start > www-data 11600 /usr/sbin/apache2 -k start > www-data 10336 /usr/sbin/apache2 -k start > www-data 11356 /usr/sbin/apache2 -k start > www-data 11348 /usr/sbin/apache2 -k start > www-data 10980 /usr/sbin/apache2 -k start > www-data 11316 /usr/sbin/apache2 -k start > www-data 6808 /usr/sbin/apache2 -k start > > > On Server2, each apache2 process uses between 120MB and 130MB of RAM ... > # ps axo 'user rss cmd' | grep apache | grep -v "\(root\|grep\|tomcat\)" > www-data 120436 /usr/sbin/apache2 -k start > www-data 119784 /usr/sbin/apache2 -k start > www-data 128720 /usr/sbin/apache2 -k start > www-data 130208 /usr/sbin/apache2 -k start > > > Why so much difference in memory used? > > After read a few documentation and googleing, I thought about loaded > modules, but there are not a lot of difference between each server... > > Server1 > # apache2 -M > Loaded Modules: > core_module (static) > so_module (static) > watchdog_module (static) > http_module (static) > log_config_module (static) > logio_module (static) > version_module (static) > unixd_module (static) > access_compat_module (shared) > actions_module (shared) > alias_module (shared) > auth_basic_module (shared) > auth_digest_module (shared) > auth_openidc_module (shared) > authn_core_module (shared) > authn_file_module (shared) > authz_core_module (shared) > authz_host_module (shared) > authz_user_module (shared) > autoindex_module (shared) > bw_module (shared) > cgi_module (shared) > dav_module (shared) > dav_fs_module (shared) > dav_lock_module (shared) > deflate_module (shared) > dir_module (shared) > env_module (shared) > expires_module (shared) > fcgid_module (shared) > filter_module (shared) > headers_module (shared) > include_module (shared) > mime_module (shared) > mpm_prefork_module (shared) > negotiation_module (shared) > proxy_module (shared) > proxy_balancer_module (shared) > proxy_fcgi_module (shared) > proxy_http_module (shared) > rewrite_module (shared) > setenvif_module (shared) > slotmem_shm_module (shared) > socache_shmcb_module (shared) > ssl_module (shared) > status_module (shared) > suexec_module (shared) > userdir_module (shared) > > Server2 > # apache2 -M > Loaded Modules: > core_module (static) > so_module (static) > watchdog_module (static) > http_module (static) > log_config_module (static) > logio_module (static) > version_module (static) > unixd_module (static) > access_compat_module (shared) > aclr_module (shared) > actions_module (shared) > alias_module (shared) > auth_basic_module (shared) > auth_digest_module (shared) > auth_openidc_module (shared) > authn_core_module (shared) > authn_file_module (shared) > authz_core_module (shared) > authz_host_module (shared) > authz_user_module (shared) > autoindex_module (shared) > cgid_module (shared) > dav_module (shared) > dav_fs_module (shared) > dav_lock_module (shared) > deflate_module (shared) > dir_module (shared) > env_module (shared) > fcgid_module (shared) > filter_module (shared) > headers_module (shared) > include_module (shared) > mime_module (shared) > mpm_event_module (shared) > negotiation_module (shared) > proxy_module (shared) > proxy_balancer_module (shared) > proxy_fcgi_module (shared) > proxy_http_module (shared) > remoteip_module (shared) > reqtimeout_module (shared) > rewrite_module (shared) > security2_module (shared) > setenvif_module (shared) > slotmem_shm_module (shared) > socache_shmcb_module (shared) > ssl_module (shared) > status_module (shared) > suexec_module (shared) > unique_id_module (shared) > userdir_module (shared) > > > I already changed MPM mode from Event to Prefork on Server2, with the same > results. > > What else can I check to understand this difference? > > Thank's! > > > > *Manxa 1876, S.L. 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