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'SEMAPHORES' are value that are set to pass info to other threads or processes.<br />
<a href="https://en.wikipedia.org/wiki/Semaphore_%28programming%29" rel="ugc">https://en.wikipedia.org/wiki/Semaphore_%28programming%29</a>
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A little more explanation here: <a href="https://dev.mysql.com/doc/mysql-em-plugin/en/myoem-metric-innodb-semaphoreactivity-category.html" rel="ugc">https://dev.mysql.com/doc/mysql-em-plugin/en/myoem-metric-innodb-semaphoreactivity-category.html</a>
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thanks for the link.<br />
<br />
however, those explanations don't explain what high values means and what can we do to avoid them!!<br />
<br />
any thoughts on that would be appreciated.<br />
<br />
Thanks,
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I have no idea and I don't know if you even need to avoid them. &nbsp;Why are you looking at them?
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the documentation doesn't say much beside the definition!! I am looking this values because I want to know if high values mean that I need more <b>resources </b>or <b>tunnings</b>
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in another words, by looking into &quot;show engine innodb status \G&quot; how can determine if my server suffers ? and not performing well, either because of disk bound, memory or cpu??
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Please click on &quot;Request Attnetion&quot; to get others to look at your question.
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<div class="content wysiwyg-content">
Hello,<br />
can some help explaining what &quot;SEMAPHORES&quot; section from innodb status means. here is an output from one of our servers<br />

<pre><code class="code-1 nolinks" id="code-10-28915087-1"><span>----------</span>
<span>SEMAPHORES</span>
<span>----------</span>
<span>OS WAIT ARRAY INFO: reservation count 389879268</span>
<span>OS WAIT ARRAY INFO: signal count 374056846</span>
<span>Mutex spin waits 592980844, rounds 1405896234, OS waits 11153864</span>
<span>RW-shared spins 451754895, rounds 12596287654, OS waits 372330619</span>
<span>RW-excl spins 7088437, rounds 125464428, OS waits 1928991</span>
<span>Spin rounds per wait: 2.37 mutex, 27.88 RW-shared, 17.70 RW-excl</span>
</code></pre>
<br />
thanks
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Hello,
can some help explaining what "SEMAPHORES" section from innodb status means. here is an output from one of our servers
(CODE)

thanks

mysql: show engine innodb status

MySQL is an open source, relational database management system that runs as a server providing multi-user access to a number of databases. Acquired by Oracle in 2009, it is frequently used in combination with PHP installations, powering most of the WordPress installations.

MySQL Server

Databases are organized collections of data, most commonly accessed through management systems including schemas, tables, queries and processes that allow users to enter and manipulate the information or utilize it in other fashions, such as with web applications or for reporting purposes.

Databases

An application server is a software framework that provides both facilities to create applications and a server environment to run them. Most application server frameworks contain a comprehensive service layer model, acting as a set of components accessible to the software developer through an API defined by the platform itself. For Web applications, these components are usually performed in the same running environment as their web server(s), and their main job is to support the construction of dynamic pages. However, many application servers target much more than just Web page generation: they implement services like clustering, fail-over, and load-balancing.

Application Servers

A server is a computer program or a machine that waits for requests from other machines or software (clients) and responds to them. This architecture is called the client–server model. The clients may run on the same computer or may connect to the server over a network. The purpose of a server is to share data or hardware and software resources among clients. Typical computing servers are database servers, file servers, mail servers, print servers, web servers, game servers, and application servers.