<?xml version="1.0" encoding="utf-8"?><!DOCTYPE article  PUBLIC '-//OASIS//DTD DocBook XML V4.4//EN'  'http://www.docbook.org/xml/4.4/docbookx.dtd'><article><articleinfo><title>ResourceLimits</title><revhistory><revision><revnumber>35</revnumber><date>2012-09-06 07:07:04</date><authorinitials>ClintonEbadi</authorinitials><revremark>this is about fyodor (!)</revremark></revision><revision><revnumber>34</revnumber><date>2009-02-25 21:00:48</date><authorinitials>AdamChlipala</authorinitials><revremark>spam</revremark></revision><revision><revnumber>33</revnumber><date>2009-02-24 16:35:49</date><authorinitials>200.222.72.2</authorinitials><revremark>http://www.message_ricboc.com/</revremark></revision><revision><revnumber>32</revnumber><date>2008-12-17 01:07:43</date><authorinitials>AdamChlipala</authorinitials><revremark>spam</revremark></revision><revision><revnumber>31</revnumber><date>2008-12-16 01:46:58</date><authorinitials>198.83.124.250</authorinitials></revision><revision><revnumber>30</revnumber><date>2008-12-16 00:34:43</date><authorinitials>AdamChlipala</authorinitials><revremark>spam</revremark></revision><revision><revnumber>29</revnumber><date>2008-12-15 18:29:29</date><authorinitials>170.35.208.23</authorinitials></revision><revision><revnumber>28</revnumber><date>2008-12-15 09:56:16</date><authorinitials>80.228.230.97</authorinitials></revision><revision><revnumber>27</revnumber><date>2008-12-15 01:42:48</date><authorinitials>198.83.124.250</authorinitials></revision><revision><revnumber>26</revnumber><date>2008-12-14 18:24:39</date><authorinitials>server88-208-239-103.live-servers.net</authorinitials></revision><revision><revnumber>25</revnumber><date>2008-12-14 18:24:26</date><authorinitials>server88-208-239-103.live-servers.net</authorinitials></revision><revision><revnumber>24</revnumber><date>2008-12-14 15:51:17</date><authorinitials>ClintonEbadi</authorinitials><revremark>Revert to revision 20.</revremark></revision><revision><revnumber>23</revnumber><date>2008-12-14 10:28:01</date><authorinitials>ns25093.ovh.net</authorinitials></revision><revision><revnumber>22</revnumber><date>2008-12-14 03:13:28</date><authorinitials>202.109.110.2</authorinitials></revision><revision><revnumber>21</revnumber><date>2008-12-14 03:13:10</date><authorinitials>202.109.110.2</authorinitials></revision><revision><revnumber>20</revnumber><date>2008-12-13 17:42:44</date><authorinitials>RyanMikulovsky</authorinitials><revremark>spam</revremark></revision><revision><revnumber>19</revnumber><date>2008-12-13 12:09:29</date><authorinitials>170.35.208.23</authorinitials><revremark>&lt;a href='http://kamada.strefa.pl/sitemap.html'&gt;webmap&lt;/a&gt; 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&lt;a href=&quot;http://clpatric.strefa.pl/sitemap.html&quot;&gt;http&lt;/a&gt; [link=http://clpatric.strefa.pl/sitemap.html]url[/link]</revremark></revision><revision><revnumber>11</revnumber><date>2008-12-11 22:25:15</date><authorinitials>170.35.208.23</authorinitials></revision><revision><revnumber>10</revnumber><date>2008-12-11 15:07:52</date><authorinitials>AdamChlipala</authorinitials><revremark>spam</revremark></revision><revision><revnumber>9</revnumber><date>2008-12-11 13:12:07</date><authorinitials>213.186.116.57.utel.net.ua</authorinitials></revision><revision><revnumber>8</revnumber><date>2008-12-11 13:11:55</date><authorinitials>213.186.116.57.utel.net.ua</authorinitials></revision><revision><revnumber>7</revnumber><date>2008-12-11 03:01:21</date><authorinitials>ppp-38-41.telesat.com.co</authorinitials></revision><revision><revnumber>6</revnumber><date>2008-12-06 13:47:01</date><authorinitials>AdamChlipala</authorinitials><revremark>vandalism</revremark></revision><revision><revnumber>5</revnumber><date>2008-12-04 23:31:20</date><authorinitials>host01.wilsonareasdips.w.subnet.rcn.com</authorinitials><revremark>domtrrac</revremark></revision><revision><revnumber>4</revnumber><date>2008-07-07 04:27:54</date><authorinitials>localhost</authorinitials><revremark>converted to 1.6 markup</revremark></revision><revision><revnumber>3</revnumber><date>2005-08-15 06:47:14</date><authorinitials>AdamChlipala</authorinitials><revremark>PHP</revremark></revision><revision><revnumber>2</revnumber><date>2005-08-15 05:40:57</date><authorinitials>AdamChlipala</authorinitials><revremark>CGI</revremark></revision><revision><revnumber>1</revnumber><date>2005-08-15 03:16:08</date><authorinitials>AdamChlipala</authorinitials></revision></revhistory></articleinfo><para>We take advantage of Linux's <code>ulimit</code> facility to limit user process' use of particular system resources.  See <ulink url="https://wiki.hcoop.net/ResourceLimits/DaemonFileSecurity#">DaemonFileSecurity</ulink> for information on disk usage limits. </para><section><title>Login and cron jobs</title><para>Login shells and cron jobs inherit the limits from <code>/etc/security/limits.conf</code>, via PAM.  We currently impose these limits, where &quot;n/m&quot; means &quot;soft limit n and hard limit m&quot;: </para><itemizedlist><listitem><para><code>as 100000/500000</code>. This limits how much virtual memory processes can allocate.  Without this, run-away processes can use up all of the memory in the system and cause daemons to start crashing due to out-of-memory errors. </para></listitem><listitem><para><code>nproc 10/20</code>. Creating an unbounded number of processes is bad, so here we limit the maximum number of processes you may own concurrently. </para></listitem></itemizedlist><para>These settings are mostly designed assuming friendly users who sometimes make mistakes and create run-away processes.  We may need to make the limits more stringent in the future. </para></section><section><title>CGI</title><para>We use a patched version of Apache 2 suexec that imposes the following restrictions on script execution: </para><itemizedlist><listitem><para>It sets some ulimits.  Currently, it limits process count to 100 and memory usage to 100 MB. </para></listitem><listitem><para>It waits up to 10 seconds for the script to execute before killing it and its children.  The child-killing business is accomplished by putting the initial script process into a new process group, and then later using <code>pkill -g</code> on that process' pid if the time-out is reached. </para></listitem></itemizedlist><para>No doubt we'll be tweaking these parameters based on experience. </para></section><section><title>PHP</title><para>We've modified suphp in the same way, so your PHP scripts run with process count, memory, and time limitations, and will be killed if they exceed them. </para><!--rule (<hr>) is not applicable to DocBook--><para> <ulink url="https://wiki.hcoop.net/ResourceLimits/CategorySystemAdministration#">CategorySystemAdministration</ulink> <ulink url="https://wiki.hcoop.net/ResourceLimits/CategoryOutdated#">CategoryOutdated</ulink> </para></section></article>