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    <title>MongoDB Jira</title>
    <link>https://jira.mongodb.org</link>
    <description>This file is an XML representation of an issue</description>
    <language>en-us</language>    <build-info>
        <version>9.7.1</version>
        <build-number>970001</build-number>
        <build-date>13-04-2023</build-date>
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<item>
            <title>[SERVER-16914] 15-second stall associated with &quot;sched: RT throttling activated&quot; under WiredTiger</title>
                <link>https://jira.mongodb.org/browse/SERVER-16914</link>
                <project id="10000" key="SERVER">Core Server</project>
                    <description>&lt;ul&gt;
	&lt;li&gt;heavy mixed workload&lt;/li&gt;
	&lt;li&gt;Ubuntu 14.04.1 LTS, 3.13.0-32-generic&lt;/li&gt;
	&lt;li&gt;VMware, 6 cores&lt;/li&gt;
&lt;/ul&gt;


&lt;p&gt;5-second pause in db ops was seen following this message in syslog:&lt;/p&gt;

&lt;p/&gt;
&lt;div id=&quot;syntaxplugin&quot; class=&quot;syntaxplugin&quot; style=&quot;border: 1px dashed #bbb; border-radius: 5px !important; overflow: auto; max-height: 30em;&quot;&gt;
&lt;table cellspacing=&quot;0&quot; cellpadding=&quot;0&quot; border=&quot;0&quot; width=&quot;100%&quot; style=&quot;font-size: 1em; line-height: 1.4em !important; font-weight: normal; font-style: normal; color: black;&quot;&gt;
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				&lt;tr id=&quot;syntaxplugin_code_and_gutter&quot;&gt;
						&lt;td  style=&quot; line-height: 1.4em !important; padding: 0em; vertical-align: top;&quot;&gt;
					&lt;pre style=&quot;font-size: 1em; margin: 0 10px;  margin-top: 10px;   margin-bottom: 10px;  width: auto; padding: 0;&quot;&gt;&lt;span style=&quot;color: black; font-family: &apos;Consolas&apos;, &apos;Bitstream Vera Sans Mono&apos;, &apos;Courier New&apos;, Courier, monospace !important;&quot;&gt;Jan 16 14:39:15 ubuntu kernel: [20023.738805] [sched_delayed] sched: RT throttling activated&lt;/span&gt;&lt;/pre&gt;
			&lt;/td&gt;
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&lt;p/&gt;

&lt;p&gt;&lt;span class=&quot;image-wrap&quot; style=&quot;&quot;&gt;&lt;img src=&quot;https://jira.mongodb.org/secure/attachment/62026/62026_throttled.png&quot; width=&quot;900&quot; style=&quot;border: 0px solid black&quot; /&gt;&lt;/span&gt;&lt;/p&gt;

&lt;ul&gt;
	&lt;li&gt;For a second or so from A to B no samples were reported by the external monitoring processes (a mongo shell process calling serverStatus and a python process monitoring system stats.)&lt;/li&gt;
	&lt;li&gt;An extremely high context switch rate was reported at A.&lt;/li&gt;
	&lt;li&gt;At B the monitoring processes resumed.&lt;/li&gt;
	&lt;li&gt;At around B (to within syslog resolution of 1 second) the above message appeared in syslog.&lt;/li&gt;
	&lt;li&gt;Starting at B for about 5 seconds db op rate dropped to 0&lt;/li&gt;
	&lt;li&gt;However not all activity was blocked: evictions appeared to be continuing, serverStatus was being processed.&lt;/li&gt;
	&lt;li&gt;&quot;slots selected for switching that were unavailable&quot; was high from B to C.&lt;/li&gt;
&lt;/ul&gt;


&lt;p&gt;It appears that some behavior involving extreme CPU utilization at high priority from A to B, possibly involving context switches, caused the kernel to suspend those threads for 5 seconds. The threads involved with eviction apparently weren&apos;t suspended.&lt;/p&gt;</description>
                <environment></environment>
        <key id="179258">SERVER-16914</key>
            <summary>15-second stall associated with &quot;sched: RT throttling activated&quot; under WiredTiger</summary>
                <type id="1" iconUrl="https://jira.mongodb.org/secure/viewavatar?size=xsmall&amp;avatarId=14703&amp;avatarType=issuetype">Bug</type>
                                            <priority id="3" iconUrl="https://jira.mongodb.org/images/icons/priorities/major.svg">Major - P3</priority>
                        <status id="6" iconUrl="https://jira.mongodb.org/images/icons/statuses/closed.png" description="The issue is considered finished, the resolution is correct. Issues which are closed can be reopened.">Closed</status>
                    <statusCategory id="3" key="done" colorName="success"/>
                                    <resolution id="9">Done</resolution>
                                        <assignee username="sue.loverso@mongodb.com">Susan LoVerso</assignee>
                                    <reporter username="bruce.lucas@mongodb.com">Bruce Lucas</reporter>
                        <labels>
                    </labels>
                <created>Fri, 16 Jan 2015 23:42:11 +0000</created>
                <updated>Tue, 21 Apr 2015 18:40:06 +0000</updated>
                            <resolved>Wed, 1 Apr 2015 18:55:02 +0000</resolved>
                                    <version>2.8.0-rc5</version>
                                    <fixVersion>3.0.1</fixVersion>
                                    <component>WiredTiger</component>
                                        <votes>0</votes>
                                    <watches>12</watches>
                                                                                                                <comments>
                            <comment id="870542" author="bruce.lucas@10gen.com" created="Wed, 1 Apr 2015 18:54:48 +0000"  >&lt;p&gt;20-minute run of this workload (100 threads mixed ops on a 6-cpu virtual machine) showed no stalls under 3.0.1, so I&apos;ll declare victory and close this ticket.&lt;/p&gt;

&lt;p&gt;&lt;span class=&quot;image-wrap&quot; style=&quot;&quot;&gt;&lt;img src=&quot;https://jira.mongodb.org/secure/attachment/69412/69412_fixed.png&quot; width=&quot;900&quot; style=&quot;border: 0px solid black&quot; /&gt;&lt;/span&gt;&lt;/p&gt;

&lt;p&gt;Cache and heap were well-behaved. VM was maybe a bit bigger than might be expected. There was a checkpoint running for much of the 20-minute run.&lt;/p&gt;</comment>
                    </comments>
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