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November, 2015 · CGSpace Notes
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<h1 class="text-primary">November, 2015</h1>
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<time datetime="2015-11-23T17:00:57+03:00">
Nov 23, 2015
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<h2 id="2015-11-22">2015-11-22</h2>
<ul>
<li>CGSpace went down</li>
<li>Looks like DSpace exhausted its PostgreSQL connection pool</li>
<li>Last week I had increased the limit from 30 to 60, which seemed to help, but now there are many more idle connections:</li>
</ul>
<pre><code>$ psql -c 'SELECT * from pg_stat_activity;' | grep idle | grep -c cgspace
78
</code></pre>
<ul>
<li>For now I have increased the limit from 60 to 90, run updates, and rebooted the server</li>
</ul>
<h2 id="2015-11-24">2015-11-24</h2>
<ul>
<li>CGSpace went down again</li>
<li>Getting emails from uptimeRobot and uptimeButler that it’s down, and Google Webmaster Tools is sending emails that there is an increase in crawl errors</li>
<li>Looks like there are still a bunch of idle PostgreSQL connections:</li>
</ul>
<pre><code>$ psql -c 'SELECT * from pg_stat_activity;' | grep idle | grep -c cgspace
96
</code></pre>
<ul>
<li>For some reason the number of idle connections is very high since we upgraded to DSpace 5</li>
</ul>
<h2 id="2015-11-25">2015-11-25</h2>
<ul>
<li>Troubleshoot the DSpace 5 OAI breakage caused by nginx routing config</li>
<li>The OAI application requests stylesheets and javascript files with the path <code>/oai/static/css</code>, which gets matched here:</li>
</ul>
<pre><code># static assets we can load from the file system directly with nginx
location ~ /(themes|static|aspects/ReportingSuite) {
try_files $uri @tomcat;
...
</code></pre>
<ul>
<li>The document root is relative to the xmlui app, so this gets a 404—I’m not sure why it doesn’t pass to <code>@tomcat</code></li>
<li>Anyways, I can’t find any URIs with path <code>/static</code>, and the more important point is to handle all the static theme assets, so we can just remove <code>static</code> from the regex for now (who cares if we can’t use nginx to send Etags for OAI CSS!)</li>
<li>Also, I noticed we aren’t setting CSP headers on the static assets, because in nginx headers are inherited in child blocks, but if you use <code>add_header</code> in a child block it doesn’t inherit the others</li>
<li>We simply need to add <code>include extra-security.conf;</code> to the above location block (but research and test first)</li>
<li>We should add WOFF assets to the list of things to set expires for:</li>
</ul>
<pre><code>location ~* \.(?:ico|css|js|gif|jpe?g|png|woff)$ {
</code></pre>
<ul>
<li>We should also add <code>aspects/Statistics</code> to the location block for static assets (minus <code>static</code> from above):</li>
</ul>
<pre><code>location ~ /(themes|aspects/ReportingSuite|aspects/Statistics) {
</code></pre>
<ul>
<li>Need to check <code>/about</code> on CGSpace, as it’s blank on my local test server and we might need to add something there</li>
<li>CGSpace has been up and down all day due to PostgreSQL idle connections (current DSpace pool is 90):</li>
</ul>
<pre><code>$ psql -c 'SELECT * from pg_stat_activity;' | grep idle | grep -c cgspace
93
</code></pre>
<ul>
<li>I looked closer at the idle connections and saw that many have been idle for hours (current time on server is <code>2015-11-25T20:20:42+0000</code>):</li>
</ul>
<pre><code>$ psql -c 'SELECT * from pg_stat_activity;' | less -S
datid | datname | pid | usesysid | usename | application_name | client_addr | client_hostname | client_port | backend_start | xact_start |
-------+----------+-------+----------+----------+------------------+-------------+-----------------+-------------+-------------------------------+-------------------------------+---
20951 | cgspace | 10966 | 18205 | cgspace | | 127.0.0.1 | | 37731 | 2015-11-25 13:13:02.837624+00 | | 20
20951 | cgspace | 10967 | 18205 | cgspace | | 127.0.0.1 | | 37737 | 2015-11-25 13:13:03.069421+00 | | 20
...
</code></pre>
<ul>
<li>There is a relevant Jira issue about this: <a href="https://jira.duraspace.org/browse/DS-1458">https://jira.duraspace.org/browse/DS-1458</a></li>
<li>It seems there is some sense changing DSpace’s default <code>db.maxidle</code> from unlimited (-1) to something like 8 (Tomcat default) or 10 (Confluence default)</li>
<li>Change <code>db.maxidle</code> from -1 to 10, reduce <code>db.maxconnections</code> from 90 to 50, and restart postgres and tomcat7</li>
<li>Also redeploy DSpace Test with a clean sync of CGSpace and mirror these database settings there as well</li>
<li>Also deploy the nginx fixes for the <code>try_files</code> location block as well as the expires block</li>
</ul>
<h2 id="2015-11-26">2015-11-26</h2>
<ul>
<li>CGSpace behaving much better since changing <code>db.maxidle</code> yesterday, but still two up/down notices from monitoring this morning (better than 50!)</li>
<li>CCAFS colleagues mentioned that the REST API is very slow, 24 seconds for one item</li>
<li>Not as bad for me, but still unsustainable if you have to get many:</li>
</ul>
<pre><code>$ curl -o /dev/null -s -w %{time_total}\\n https://cgspace.cgiar.org/rest/handle/10568/32802?expand=all
8.415
</code></pre>
<ul>
<li>Monitoring e-mailed in the evening to say CGSpace was down</li>
<li>Idle connections in PostgreSQL again:</li>
</ul>
<pre><code>$ psql -c 'SELECT * from pg_stat_activity;' | grep cgspace | grep -c idle
66
</code></pre>
<ul>
<li>At the time, the current DSpace pool size was 50…</li>
<li>I reduced the pool back to the default of 30, and reduced the <code>db.maxidle</code> settings from 10 to 8</li>
</ul>
<h2 id="2015-11-29">2015-11-29</h2>
<ul>
<li>Still more alerts that CGSpace has been up and down all day</li>
<li>Current database settings for DSpace:</li>
</ul>
<pre><code>db.maxconnections = 30
db.maxwait = 5000
db.maxidle = 8
db.statementpool = true
</code></pre>
<ul>
<li>And idle connections:</li>
</ul>
<pre><code>$ psql -c 'SELECT * from pg_stat_activity;' | grep cgspace | grep -c idle
49
</code></pre>
<ul>
<li>Perhaps I need to start drastically increasing the connection limits—like to 300—to see if DSpace’s thirst can ever be quenched</li>
<li>On another note, SUNScholar’s notes suggest adjusting some other postgres variables: <a href="http://wiki.lib.sun.ac.za/index.php/SUNScholar/Optimisations/Database">http://wiki.lib.sun.ac.za/index.php/SUNScholar/Optimisations/Database</a></li>
<li>This might help with REST API speed (which I mentioned above and still need to do real tests)</li>
</ul>
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