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<channel>
    <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>
    </build-info>


<item>
            <title>[SERVER-22834] 1.7x performance regression in random queries</title>
                <link>https://jira.mongodb.org/browse/SERVER-22834</link>
                <project id="10000" key="SERVER">Core Server</project>
                    <description>&lt;ul&gt;
	&lt;li&gt;standalone, 3 GB cache&lt;/li&gt;
	&lt;li&gt;10 GB data set, 10 M x 1 kB documents&lt;/li&gt;
	&lt;li&gt;64 GB memory, SSD (but probably not relevant as data set should be in filesystem cache)&lt;/li&gt;
	&lt;li&gt;100 threads doing random queries over data set, creating high cache pressure&lt;/li&gt;
	&lt;li&gt;observe ~1.7x performance regression in 3.2.3 compared to 3.0.9&lt;/li&gt;
&lt;/ul&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/110455/110455_regression.png&quot; width=&quot;100%&quot; style=&quot;border: 0px solid black&quot; /&gt;&lt;/span&gt;&lt;/p&gt;

&lt;ul&gt;
	&lt;li&gt;A-B: 3.0.9&lt;/li&gt;
	&lt;li&gt;B-C: 3.2.3 (same data set)&lt;/li&gt;
&lt;/ul&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;   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;                   3.0.9         3.2.3&lt;/span&gt;&lt;/pre&gt;
			&lt;/td&gt;
		&lt;/tr&gt;
				&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;   width: auto; padding: 0;&quot;&gt;&amp;nbsp;&lt;/pre&gt;
			&lt;/td&gt;
		&lt;/tr&gt;
				&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;   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;queries             82 k/s        48 k/s&lt;/span&gt;&lt;/pre&gt;
			&lt;/td&gt;
		&lt;/tr&gt;
				&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;   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;evictions           78 k/s        36 k/s&lt;/span&gt;&lt;/pre&gt;
			&lt;/td&gt;
		&lt;/tr&gt;
				&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;   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;walked             836 k/s      5813 k/s&lt;/span&gt;&lt;/pre&gt;
			&lt;/td&gt;
		&lt;/tr&gt;
				&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;   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;walked/eviction     11           160&lt;/span&gt;&lt;/pre&gt;
			&lt;/td&gt;
		&lt;/tr&gt;
				&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-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;mutex calls        0.7 k/s        12 k/s&lt;/span&gt;&lt;/pre&gt;
			&lt;/td&gt;
		&lt;/tr&gt;
			&lt;/tbody&gt;
&lt;/table&gt;
&lt;/div&gt;
&lt;p/&gt;

&lt;p&gt;It appears that a higher rate of pages walked per page evicted could be a significant factor, so possibly this is related to &lt;a href=&quot;https://jira.mongodb.org/browse/SERVER-22831&quot; title=&quot;Low query rate with heavy cache pressure and an idle collection&quot; class=&quot;issue-link&quot; data-issue-key=&quot;SERVER-22831&quot;&gt;&lt;del&gt;SERVER-22831&lt;/del&gt;&lt;/a&gt;, where pages walked for eviction also appeared to be a factor? (Note however that ticket requires a replica set, whereas this ticket is for a standalone mongod.)&lt;/p&gt;

&lt;p&gt;There is also a much higher rate of mutex calls.&lt;/p&gt;</description>
                <environment></environment>
        <key id="267722">SERVER-22834</key>
            <summary>1.7x performance regression in random queries</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>Wed, 24 Feb 2016 16:39:31 +0000</created>
                <updated>Fri, 24 Jun 2016 12:20:03 +0000</updated>
                            <resolved>Fri, 24 Jun 2016 12:18:47 +0000</resolved>
                                                    <fixVersion>3.3.6</fixVersion>
                                    <component>WiredTiger</component>
                                        <votes>0</votes>
                                    <watches>18</watches>
                                                                                                                <comments>
                            <comment id="1300961" author="ramon.fernandez" created="Tue, 21 Jun 2016 11:26:30 +0000"  >&lt;p&gt;The work to address this performance regression was done as part of the linked WT tickets, merged into MongoDB as of 3.3.6.&lt;/p&gt;

&lt;p&gt;&lt;b&gt;EDIT&lt;/b&gt;: I&apos;ve re-classified the resolution on this ticket as &quot;Fixed&quot;, since many users will search the SERVER project when having issues, and I think is better to indicate that this problem was fixed even if the actual code changes happened on the linked WT tickets.&lt;/p&gt;</comment>
                            <comment id="1269368" author="sue.loverso" created="Thu, 19 May 2016 20:11:55 +0000"  >&lt;p&gt;I reran this script comparing the mongodb-3.0 WT branch with all the recent eviction changes on WT develop (changeset 88801726).  I compared the inserts (not talked earlier about but interesting) and the query rates.  For the query rates, I took the middle 90 seconds of throughput output from mongostat from the query-only workload.&lt;/p&gt;

&lt;p&gt;What I see is that current develop is slightly below 3.0 but much, much more stable.  For inserts:&lt;/p&gt;
&lt;div class=&apos;table-wrap&apos;&gt;
&lt;table class=&apos;confluenceTable&apos;&gt;&lt;tbody&gt;
&lt;tr&gt;
&lt;th class=&apos;confluenceTh&apos;&gt; Branch &lt;/th&gt;
&lt;th class=&apos;confluenceTh&apos;&gt; Total Load Time &lt;/th&gt;
&lt;th class=&apos;confluenceTh&apos;&gt; Avg Inserts/sec &lt;/th&gt;
&lt;th class=&apos;confluenceTh&apos;&gt; Range/sec &lt;/th&gt;
&lt;/tr&gt;
&lt;tr&gt;
&lt;td class=&apos;confluenceTd&apos;&gt; 3.0 &lt;/td&gt;
&lt;td class=&apos;confluenceTd&apos;&gt; 122 seconds &lt;/td&gt;
&lt;td class=&apos;confluenceTd&apos;&gt; 81967 &lt;/td&gt;
&lt;td class=&apos;confluenceTd&apos;&gt; 19585-103744 &lt;/td&gt;
&lt;/tr&gt;
&lt;tr&gt;
&lt;td class=&apos;confluenceTd&apos;&gt; develop &lt;/td&gt;
&lt;td class=&apos;confluenceTd&apos;&gt; 49 seconds &lt;/td&gt;
&lt;td class=&apos;confluenceTd&apos;&gt; 204081 &lt;/td&gt;
&lt;td class=&apos;confluenceTd&apos;&gt; 106360-236144 &lt;/td&gt;
&lt;/tr&gt;
&lt;/tbody&gt;&lt;/table&gt;
&lt;/div&gt;


&lt;p&gt;For queries (90 seconds) you can see the tight stable range for develop:&lt;/p&gt;
&lt;div class=&apos;table-wrap&apos;&gt;
&lt;table class=&apos;confluenceTable&apos;&gt;&lt;tbody&gt;
&lt;tr&gt;
&lt;th class=&apos;confluenceTh&apos;&gt; Branch &lt;/th&gt;
&lt;th class=&apos;confluenceTh&apos;&gt; Avg Queries/sec &lt;/th&gt;
&lt;th class=&apos;confluenceTh&apos;&gt; Range/sec &lt;/th&gt;
&lt;/tr&gt;
&lt;tr&gt;
&lt;td class=&apos;confluenceTd&apos;&gt; 3.0 &lt;/td&gt;
&lt;td class=&apos;confluenceTd&apos;&gt; 21124 &lt;/td&gt;
&lt;td class=&apos;confluenceTd&apos;&gt; 14980-25659 (71%) &lt;/td&gt;
&lt;/tr&gt;
&lt;tr&gt;
&lt;td class=&apos;confluenceTd&apos;&gt; develop &lt;/td&gt;
&lt;td class=&apos;confluenceTd&apos;&gt; 19779 (-6%) &lt;/td&gt;
&lt;td class=&apos;confluenceTd&apos;&gt; 18914-20394 (8%) &lt;/td&gt;
&lt;/tr&gt;
&lt;/tbody&gt;&lt;/table&gt;
&lt;/div&gt;
</comment>
                            <comment id="1251913" author="dan@10gen.com" created="Mon, 2 May 2016 14:50:26 +0000"  >&lt;p&gt;Pretty sure the repro script can be found in &lt;a href=&quot;https://jira.mongodb.org/browse/SERVER-22831?focusedCommentId=1183307&amp;amp;page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel#comment-1183307&quot; class=&quot;external-link&quot; rel=&quot;nofollow&quot;&gt;this comment&lt;/a&gt; which is from &lt;a href=&quot;https://jira.mongodb.org/browse/SERVER-22831&quot; title=&quot;Low query rate with heavy cache pressure and an idle collection&quot; class=&quot;issue-link&quot; data-issue-key=&quot;SERVER-22831&quot;&gt;&lt;del&gt;SERVER-22831&lt;/del&gt;&lt;/a&gt;.&lt;/p&gt;</comment>
                            <comment id="1251884" author="sue.loverso" created="Mon, 2 May 2016 14:31:29 +0000"  >&lt;p&gt;&lt;a href=&quot;https://jira.mongodb.org/secure/ViewProfile.jspa?name=bruce.lucas&quot; class=&quot;user-hover&quot; rel=&quot;bruce.lucas&quot;&gt;bruce.lucas&lt;/a&gt; or &lt;a href=&quot;https://jira.mongodb.org/secure/ViewProfile.jspa?name=david.hows&quot; class=&quot;user-hover&quot; rel=&quot;david.hows&quot;&gt;david.hows&lt;/a&gt; can one of you post the test script to the ticket?  I&apos;d like to test with the recent eviction fix.  I think it will help this workload and I&apos;d like to run comparisons.&lt;/p&gt;</comment>
                            <comment id="1239603" author="michael.cahill" created="Tue, 19 Apr 2016 03:08:44 +0000"  >&lt;p&gt;&lt;a href=&quot;https://jira.mongodb.org/secure/ViewProfile.jspa?name=sue.loverso&quot; class=&quot;user-hover&quot; rel=&quot;sue.loverso&quot;&gt;sue.loverso&lt;/a&gt;, once the dust has settled on the eviction work you are currently doing, can you please go back to this MongoDB workload and compare the performance of MongoDB 3.0 with MongoDB master + WT develop?&lt;/p&gt;</comment>
                            <comment id="1207615" author="david.hows" created="Fri, 18 Mar 2016 06:51:55 +0000"  >&lt;p&gt;Following up on the work from the other day I have begun looking to see if there are any common factors amongst the pages being evicted by WT.&lt;/p&gt;

&lt;p&gt;From what I have gathered sofar the most common pages evicted are index pages, this is not unexpected as there are far fewer index pages, meaning that we can expect to see more repetition. The interesting part is that the most popular of these pages are also the smallest. In the last several runs the most evicted 3 pages are all at a minimum 5x smaller than the average index page size. (5K pages vs 20K average). &lt;/p&gt;

&lt;p&gt;A follow up test that moved the index page size to 32K from the default of 16K showed the same behaviour, with an average page size of 40K~ and the most commonly evicted pages being 5K followed by 6K for the second most commonly evicted page.&lt;/p&gt;

&lt;p&gt;Still more work to do here, want to understand why these small index pages seem to be in such high demand.&lt;/p&gt;</comment>
                            <comment id="1206365" author="david.hows" created="Thu, 17 Mar 2016 06:10:54 +0000"  >&lt;blockquote&gt;&lt;p&gt;Are those hex values pointers to something (like a WT_REF)? &lt;/p&gt;&lt;/blockquote&gt;
&lt;p&gt;Its a pointer to a &lt;tt&gt;WT_PAGE&lt;/tt&gt; object&lt;/p&gt;
&lt;blockquote&gt;&lt;p&gt;What does it mean for there to be one or two pages being evicted this frequently &#8211; is this a count of successful evictions or just attempts?&lt;/p&gt;&lt;/blockquote&gt;
&lt;p&gt;These are pages picked as eviction candidates. I&apos;m keying on the verbose message at &lt;tt&gt;evict_lru.c:1404&lt;/tt&gt;&lt;/p&gt;
&lt;blockquote&gt;&lt;p&gt;Lastly, since we are just talking about 1-2 pages, can you see where they are in the tree somehow?&lt;/p&gt;&lt;/blockquote&gt;
&lt;p&gt;I&apos;m doing a tree review now, want to confirm that the trees are roughly the same.&lt;/p&gt;</comment>
                            <comment id="1206359" author="michael.cahill" created="Thu, 17 Mar 2016 06:03:04 +0000"  >&lt;p&gt;Are those hex values pointers to something (like a &lt;tt&gt;WT_REF&lt;/tt&gt;)?&lt;/p&gt;

&lt;p&gt;What does it mean for there to be one or two pages being evicted this frequently &amp;#8211; is this a count of successful evictions or just attempts?&lt;/p&gt;

&lt;p&gt;Lastly, since we are just talking about 1-2 pages, can you see where they are in the tree somehow?&lt;/p&gt;</comment>
                            <comment id="1204826" author="david.hows" created="Wed, 16 Mar 2016 03:30:47 +0000"  >&lt;p&gt;I have done a further dive after my last disastrous conclusion.&lt;/p&gt;

&lt;p&gt;Having run 3.0 and 3.2 with some extra debug flags I can see the following:&lt;/p&gt;

&lt;p&gt;Average size of page evicted vs number of pages evicted&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;
		&lt;tbody &gt;
				&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;   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;new&lt;/span&gt;&lt;/pre&gt;
			&lt;/td&gt;
		&lt;/tr&gt;
				&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;   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;   avg: 24000.5 over: 3424505&lt;/span&gt;&lt;/pre&gt;
			&lt;/td&gt;
		&lt;/tr&gt;
				&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;   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;old&lt;/span&gt;&lt;/pre&gt;
			&lt;/td&gt;
		&lt;/tr&gt;
				&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-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;   avg: 24176.2 over: 2882505&lt;/span&gt;&lt;/pre&gt;
			&lt;/td&gt;
		&lt;/tr&gt;
			&lt;/tbody&gt;
&lt;/table&gt;
&lt;/div&gt;
&lt;p/&gt;

&lt;p&gt;Top 10 pages evicted by count*&lt;br/&gt;
&lt;b&gt;Old&lt;/b&gt;&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;
		&lt;tbody &gt;
				&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;   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;    373 0x2b9be400,&lt;/span&gt;&lt;/pre&gt;
			&lt;/td&gt;
		&lt;/tr&gt;
				&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;   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;    373 0x2c9f2c00,&lt;/span&gt;&lt;/pre&gt;
			&lt;/td&gt;
		&lt;/tr&gt;
				&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;   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;    374 0x20b96c00,&lt;/span&gt;&lt;/pre&gt;
			&lt;/td&gt;
		&lt;/tr&gt;
				&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;   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;    375 0x19264c00,&lt;/span&gt;&lt;/pre&gt;
			&lt;/td&gt;
		&lt;/tr&gt;
				&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;   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;    375 0x3ae1e800,&lt;/span&gt;&lt;/pre&gt;
			&lt;/td&gt;
		&lt;/tr&gt;
				&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;   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;    376 0x1a948c00,&lt;/span&gt;&lt;/pre&gt;
			&lt;/td&gt;
		&lt;/tr&gt;
				&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;   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;    378 0x19af2800,&lt;/span&gt;&lt;/pre&gt;
			&lt;/td&gt;
		&lt;/tr&gt;
				&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;   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;    378 0xc338000,&lt;/span&gt;&lt;/pre&gt;
			&lt;/td&gt;
		&lt;/tr&gt;
				&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;   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;    381 0x367dc400,&lt;/span&gt;&lt;/pre&gt;
			&lt;/td&gt;
		&lt;/tr&gt;
				&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-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;   2171 0x1d63af60,&lt;/span&gt;&lt;/pre&gt;
			&lt;/td&gt;
		&lt;/tr&gt;
			&lt;/tbody&gt;
&lt;/table&gt;
&lt;/div&gt;
&lt;p/&gt;

&lt;p&gt;&lt;b&gt;New&lt;/b&gt;&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;
		&lt;tbody &gt;
				&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;   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;    211 0x38de8000,&lt;/span&gt;&lt;/pre&gt;
			&lt;/td&gt;
		&lt;/tr&gt;
				&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;   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;    212 0x138da400,&lt;/span&gt;&lt;/pre&gt;
			&lt;/td&gt;
		&lt;/tr&gt;
				&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;   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;    212 0x145fe800,&lt;/span&gt;&lt;/pre&gt;
			&lt;/td&gt;
		&lt;/tr&gt;
				&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;   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;    212 0x184a4800,&lt;/span&gt;&lt;/pre&gt;
			&lt;/td&gt;
		&lt;/tr&gt;
				&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;   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;    212 0x3a7d6c00,&lt;/span&gt;&lt;/pre&gt;
			&lt;/td&gt;
		&lt;/tr&gt;
				&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;   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;    212 0x8fbc400,&lt;/span&gt;&lt;/pre&gt;
			&lt;/td&gt;
		&lt;/tr&gt;
				&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;   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;    213 0x1d20cc00,&lt;/span&gt;&lt;/pre&gt;
			&lt;/td&gt;
		&lt;/tr&gt;
				&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;   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;    216 0x406e0c00,&lt;/span&gt;&lt;/pre&gt;
			&lt;/td&gt;
		&lt;/tr&gt;
				&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;   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;   2123 0xdcd4f60,&lt;/span&gt;&lt;/pre&gt;
			&lt;/td&gt;
		&lt;/tr&gt;
				&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-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;   3578 0x459c5a0&lt;/span&gt;&lt;/pre&gt;
			&lt;/td&gt;
		&lt;/tr&gt;
			&lt;/tbody&gt;
&lt;/table&gt;
&lt;/div&gt;
&lt;p/&gt;</comment>
                            <comment id="1200164" author="david.hows" created="Fri, 11 Mar 2016 06:58:55 +0000"  >&lt;p&gt;Trying to get some diagnostic data out as to what differs in how the data is processed in WT between versions.&lt;/p&gt;

&lt;p&gt;I accidentally linked MongoDB 3.0 against a compile of WT taken from the head of develop.&lt;/p&gt;

&lt;p&gt;This STILL showed the same performance degradation. So i suspect that the issue here is outside WT itself.&lt;/p&gt;

&lt;p&gt;Will follow this up further soon.&lt;/p&gt;</comment>
                            <comment id="1189884" author="david.hows" created="Wed, 2 Mar 2016 01:31:02 +0000"  >&lt;p&gt;I&apos;ve gone and reviewed these changes and found that MongoDB master still suffers a major regression. MongoDB 3.0.9 throughput 27923.7 vs. MongoDB Master 19358.4. Will chase further tomorrow.&lt;/p&gt;

&lt;p&gt;Please ignore my earlier version of this comment as I found a bug in my version of this script.&lt;/p&gt;</comment>
                            <comment id="1188716" author="michael.cahill" created="Tue, 1 Mar 2016 06:08:24 +0000"  >&lt;p&gt;&lt;a href=&quot;https://jira.mongodb.org/secure/ViewProfile.jspa?name=david.hows&quot; class=&quot;user-hover&quot; rel=&quot;david.hows&quot;&gt;david.hows&lt;/a&gt;, can you please repro &lt;a href=&quot;https://jira.mongodb.org/secure/ViewProfile.jspa?name=bruce.lucas&quot; class=&quot;user-hover&quot; rel=&quot;bruce.lucas&quot;&gt;bruce.lucas&lt;/a&gt;&apos;s work, and also test against the tip of 3.2 and master to see whether recent eviction work has had any impact?&lt;/p&gt;</comment>
                    </comments>
                <issuelinks>
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