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    <title>Mojang Studios Jira</title>
    <link>https://bugs.mojang.com</link>
    <description>This file is an XML representation of an issue</description>
    <language>en</language>    <build-info>
        <version>9.12.2</version>
        <build-number>9120002</build-number>
        <build-date>10-01-2024</build-date>
    </build-info>


<item>
            <title>[MCPE-21038] Spreading speed of water is not always faster than that of lava</title>
                <link>https://bugs.mojang.com/browse/MCPE-21038</link>
                <project id="10200" key="MCPE">Minecraft (Bedrock codebase)</project>
                    <description>&lt;p&gt;Spreading speed of water should be guaranteed to be faster than that of lava in the Overworld. However in the current implementation, water is only &lt;em&gt;statistically&lt;/em&gt; faster and has a small chance of getting overtaken by lava.&lt;/p&gt;

&lt;p&gt;This is usually not a problem and could even be WAI but for smooth stone generators the difference of speed is crucial.&lt;/p&gt;

&lt;p&gt;&lt;b&gt;Steps to reproduce:&lt;/b&gt;&lt;/p&gt;
&lt;ol&gt;
	&lt;li&gt;Open the attached test world.&lt;/li&gt;
	&lt;li&gt;Push the &quot;reset&quot; button to initialize the state of the contraption.&lt;/li&gt;
	&lt;li&gt;Grab some coffee while looking at the machine absent-mindedly. It may take several tens of minutes to pose the problem.&lt;/li&gt;
&lt;/ol&gt;


&lt;p&gt;&lt;b&gt;What I expect to happen:&lt;/b&gt;&lt;br/&gt;
The machine keeps generating stone blocks indefinitely.&lt;/p&gt;

&lt;p&gt;&lt;b&gt;What actually happens:&lt;/b&gt;&lt;br/&gt;
Flowing lava occasionally lands on the air block in front of the piston, before the water stream pours into the said space. When this happens water ends up flowing into the lava stream horizontally, which does not generate any blocks as expected, and finally the lava stream tries to flow horizontally into water, generating a cobblestone block blocking the water stream and the machine is dead.&lt;/p&gt;</description>
            <key id="167456">MCPE-21038</key>
            <summary>Spreading speed of water is not always faster than that of lava</summary>
                <type id="1" iconUrl="https://bugs.mojang.com/secure/viewavatar?size=xsmall&amp;avatarId=18903&amp;avatarType=issuetype">Bug</type>
                                    <status id="4" iconUrl="https://bugs.mojang.com/images/icons/statuses/reopened.png" description="This issue was once resolved, but the resolution was deemed incorrect. From here issues are either marked assigned or resolved.">Reopened</status>
                    <statusCategory id="2" key="new" colorName="default"/>
                                    <resolution id="-1">Unresolved</resolution>
                                            <reporter username="depressed-pho">PHO</reporter>
                        <labels>
                            <label>lava</label>
                            <label>water</label>
                    </labels>
                <created>Fri, 7 Apr 2017 14:24:33 +0200</created>
                <updated>Tue, 7 Jan 2025 16:14:20 +0100</updated>
                                            <version>1.20.10.21 Preview</version>
                    <version>1.0.5.54</version>
                    <version>1.2.1.1</version>
                    <version>1.11.4</version>
                    <version>1.13.0.2 Beta</version>
                    <version>1.12.1</version>
                    <version>1.12.0</version>
                    <version>1.16.20</version>
                    <version>1.19.83 Hotfix</version>
                    <version>1.20.0</version>
                    <version>1.20.62 Hotfix</version>
                    <version>1.21.51 Hotfix</version>
                                                                        <votes>13</votes>
                                    <watches>7</watches>
                                                                            <comments>
                            <comment id="1260800" author="goldenhelmet" created="Tue, 6 Jun 2023 04:05:01 +0200"  >&lt;p&gt;I have been running the machine in the test world for a half hour or more in 1.20.10.21 Preview and have not reproduced the issue with the preset clock circuit timings. &lt;b&gt;However&lt;/b&gt;, the issue does sometimes reproduce if you adjust the repeater delays in the clock circuit while the machine is running. Therefore, I am not sure if the originally reported &quot;statistical&quot; random variance in spreading speed was fixed at some point, or, alternatively, if the description overlooked user input. &lt;em&gt;It is possible that the original random variance was due to random ticks of lava being treated the same way as the block updates described below, and at some point the lava random tick logic was refactored but that refactoring was not applied to block update lava ticks.&lt;/em&gt;&lt;/p&gt;

&lt;p&gt;In the current release (1.19.83) and Preview (1.20.10.21) there is no randomness in lava and water spread &lt;em&gt;speed&lt;/em&gt;: lava always attempts to spread 30 game ticks after receiving a block update from an adjacent block, and water attempts spread 5 game ticks after receiving a block update from an adjacent block. &lt;/p&gt;

&lt;p&gt;What causes unexpected results for players is that &lt;em&gt;the delay does not get reset by subsequent block updates&lt;/em&gt;. This means that lava can &lt;em&gt;appear&lt;/em&gt; to spread faster than water if you time block updates carefully. Thus, the unexpected behavior described in the &lt;a href=&quot;https://bugs.mojang.com/browse/MCPE-21038?focusedId=644320&amp;amp;page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel#comment-644320&quot; class=&quot;external-link&quot; rel=&quot;nofollow&quot;&gt;comment by Twilac&lt;/a&gt; can be reproduced by breaking the stone 26-29 ticks after it forms (or just under 1.5 seconds): &lt;span class=&quot;nobr&quot;&gt;&lt;a href=&quot;https://bugs.mojang.com/secure/attachment/536724/536724_Lava+overtakes+water.mp4&quot; title=&quot;Lava overtakes water.mp4 attached to MCPE-21038&quot;&gt;Lava overtakes water.mp4&lt;sup&gt;&lt;img class=&quot;rendericon&quot; src=&quot;https://bugs.mojang.com/images/icons/link_attachment_7.gif&quot; height=&quot;7&quot; width=&quot;7&quot; align=&quot;absmiddle&quot; alt=&quot;&quot; border=&quot;0&quot;/&gt;&lt;/sup&gt;&lt;/a&gt;&lt;/span&gt;&lt;/p&gt;

&lt;p&gt;It is even possible to create the appearance of instant spread with precise delay:  &lt;span class=&quot;nobr&quot;&gt;&lt;a href=&quot;https://bugs.mojang.com/secure/attachment/536725/536725_Instead+spread.mp4&quot; title=&quot;Instead spread.mp4 attached to MCPE-21038&quot;&gt;Instead spread.mp4&lt;sup&gt;&lt;img class=&quot;rendericon&quot; src=&quot;https://bugs.mojang.com/images/icons/link_attachment_7.gif&quot; height=&quot;7&quot; width=&quot;7&quot; align=&quot;absmiddle&quot; alt=&quot;&quot; border=&quot;0&quot;/&gt;&lt;/sup&gt;&lt;/a&gt;&lt;/span&gt;&lt;/p&gt;

&lt;p&gt;This behavior is part of the underlying cause of &lt;a href=&quot;https://bugs.mojang.com/browse/MCPE-48128&quot; title=&quot;Cobblestone generating too fast&quot; class=&quot;issue-link&quot; data-issue-key=&quot;MCPE-48128&quot;&gt;MCPE-48128&lt;/a&gt; / &lt;a href=&quot;https://bugs.mojang.com/browse/MCPE-73342&quot; title=&quot;Adjacent block updates causes liquids and fire to spread faster&quot; class=&quot;issue-link&quot; data-issue-key=&quot;MCPE-73342&quot;&gt;MCPE-73342&lt;/a&gt;. The issues described in those reports also rely on an additional factor: &lt;em&gt;in some cases it seems that the delayed block updates stack&lt;/em&gt;. By &quot;stack&quot; I mean that the liquid &quot;remembers&quot; each update it receives and makes an attempt to spread at the expected delay from each block update. As a result, the liquid can &lt;em&gt;appear&lt;/em&gt; to spread faster if it has been repeatedly updated for a period time before it is actually able to spread. This &quot;warm up&quot; can be done by a fast clock circuit updating blocks as described in &lt;a href=&quot;https://bugs.mojang.com/browse/MCPE-73342&quot; title=&quot;Adjacent block updates causes liquids and fire to spread faster&quot; class=&quot;issue-link&quot; data-issue-key=&quot;MCPE-73342&quot;&gt;MCPE-73342&lt;/a&gt;, or just by mining and generating blocks as in shown in the video attached to &lt;a href=&quot;https://bugs.mojang.com/browse/MCPE-48128&quot; title=&quot;Cobblestone generating too fast&quot; class=&quot;issue-link&quot; data-issue-key=&quot;MCPE-48128&quot;&gt;MCPE-48128&lt;/a&gt;.&lt;/p&gt;

&lt;p&gt;When considering whether or how to patch this issue, please keep in mind&lt;/p&gt;
&lt;ul&gt;
	&lt;li&gt;The ability to stack liquid spread updates is used to increase rates in stone, cobblestone, and moss farms. A basic stone generator is 2.5x faster using stacked updates.&lt;/li&gt;
	&lt;li&gt;The ability to stack fire spread updates is used to run portal ticking gold farms. Ticking a portal with stacked updates is about 2x faster than using lava spam and random ticks.&lt;/li&gt;
	&lt;li&gt;&lt;em&gt;Full&lt;/em&gt; Java parity. Stacking liquid updates/pending ticks does not seem to occur in Java Edition, but it would be bad for the community to nerf the above-mentioned farms in Bedrock without considering whether Bedrock players will be able to switch to Java designs or have comparable alternatives after the patch.&lt;/li&gt;
&lt;/ul&gt;
</comment>
                            <comment id="1218780" author="arisabot" created="Fri, 30 Dec 2022 08:35:12 +0100"  >&lt;p&gt;This report is currently missing crucial information. Please take a look at the other comments to find out what we are looking for.&lt;br/&gt;
If you added the required information and a moderator sees your comment, they will reopen and update the report. However, if you think your update to this report has been overlooked or you want to make sure that this report is reopened, you can contact the Mojira staff on &lt;a href=&quot;https://discordapp.com/invite/rpCyfKV&quot; class=&quot;external-link&quot; target=&quot;_blank&quot; rel=&quot;nofollow noopener&quot;&gt;Discord&lt;/a&gt; or &lt;a href=&quot;https://www.reddit.com/r/Mojira/&quot; class=&quot;external-link&quot; target=&quot;_blank&quot; rel=&quot;nofollow noopener&quot;&gt;Reddit&lt;/a&gt;.&lt;br/&gt;
&lt;sub&gt;&lt;font color=&quot;#888&quot;&gt;&amp;#8211; I am a bot. This action was performed automatically! If you think it was incorrect, please notify us on &lt;a href=&quot;https://discordapp.com/invite/rpCyfKV&quot; class=&quot;external-link&quot; target=&quot;_blank&quot; rel=&quot;nofollow noopener&quot;&gt;Discord&lt;/a&gt; or &lt;a href=&quot;https://www.reddit.com/r/Mojira/&quot; class=&quot;external-link&quot; target=&quot;_blank&quot; rel=&quot;nofollow noopener&quot;&gt;Reddit&lt;/a&gt;&lt;/font&gt;&lt;/sub&gt;&lt;/p&gt;</comment>
                            <comment id="1218779" author="red_paladin" created="Fri, 30 Dec 2022 08:35:06 +0100"  >&lt;p&gt;just tried to make a stone generator in Window bedrock edition and I&apos;m having this exact same problem, lava randomly flows faster than water when you break multiple blocks in rapid succession...&lt;/p&gt;

&lt;p&gt;&#160;&lt;/p&gt;</comment>
                            <comment id="1038826" author="mega_spud" created="Sat, 17 Jul 2021 12:01:16 +0200"  >&lt;p&gt;&lt;b&gt;Thank you for your report!&lt;/b&gt;&lt;br/&gt;
However, this issue has been temporarily closed as &lt;b&gt;&lt;font color=&quot;#FF5722&quot;&gt;Awaiting Response&lt;/font&gt;&lt;/b&gt;&lt;/p&gt;

&lt;p&gt;Is this still an issue in the latest version? If so, please make sure the ticket description contains the following information:&lt;/p&gt;

&lt;blockquote&gt;
&lt;p&gt;&lt;b&gt;Steps to Reproduce:&lt;/b&gt;&lt;br/&gt;
1.&lt;br/&gt;
2.&lt;br/&gt;
3.&lt;/p&gt;

&lt;p&gt;&lt;b&gt;Observed Results:&lt;/b&gt;&lt;br/&gt;
&lt;em&gt;(Briefly describe what happens)&lt;/em&gt;&lt;/p&gt;

&lt;p&gt;&lt;b&gt;Expected Results:&lt;/b&gt;&lt;br/&gt;
&lt;em&gt;(Briefly describe what should happen)&lt;/em&gt;&lt;/p&gt;
&lt;/blockquote&gt;

&lt;p&gt;If your ticket does not look like the example given &lt;a href=&quot;https://help.minecraft.net/hc/en-us/articles/360049840492-Mojang-Bug-Tracker-Guidelines#h_01EKCG7QWCA1Z3MJN75C9JBMFC&quot; class=&quot;external-link&quot; target=&quot;_blank&quot; rel=&quot;nofollow noopener&quot;&gt;here&lt;/a&gt;, then it&apos;s likely to be closed as incomplete.&lt;/p&gt;

&lt;p&gt;This ticket will automatically reopen when you reply.&lt;/p&gt;

&lt;p&gt;&lt;b&gt;Quick Links&lt;/b&gt;:&lt;br/&gt;
&#128211; &lt;a href=&quot;https://aka.ms/MCBugTrackerHelp&quot; title=&quot;How To Write Awesome Tickets! &#128175;&quot; class=&quot;external-link&quot; target=&quot;_blank&quot; rel=&quot;nofollow noopener&quot;&gt;Issue Guidelines&lt;/a&gt; &amp;#8211; &#128172; &lt;a href=&quot;https://help.minecraft.net/hc/en-us/requests/new&quot; title=&quot;Account Support &#128377;&quot; class=&quot;external-link&quot; target=&quot;_blank&quot; rel=&quot;nofollow noopener&quot;&gt;Mojang Support&lt;/a&gt; &amp;#8211; &#128231; &lt;a href=&quot;https://feedback.minecraft.net/&quot; title=&quot;Feedback and Suggestions &#9997;&#65039;&quot; class=&quot;external-link&quot; target=&quot;_blank&quot; rel=&quot;nofollow noopener&quot;&gt;Suggestions&lt;/a&gt; &amp;#8211; &#128214; &lt;a href=&quot;http://minecraft.gamepedia.com/Minecraft_Wiki&quot; title=&quot;Minecraft Wiki &#127891;&quot; class=&quot;external-link&quot; target=&quot;_blank&quot; rel=&quot;nofollow noopener&quot;&gt;Minecraft Wiki&lt;/a&gt;&lt;/p&gt;</comment>
                            <comment id="795773" author="goldenhelmet" created="Tue, 25 Aug 2020 16:44:38 +0200"  >&lt;p&gt;I have reproduced this in the test world in 1.16.20. It took over half an hour for the machine to break, and it may have only broken while I was switching windows to put Minecraft in the background so I could update other tickets.&lt;/p&gt;</comment>
                            <comment id="644320" author="twilac" created="Sat, 7 Mar 2020 16:21:26 +0100"  >&lt;p&gt;I&apos;ve been able to reliable reproduce this in 1.14.30, but only with lava dropping in to water.&lt;/p&gt;

&lt;p&gt;Just break the stone repeatedly and in just a few tries the lava will update before the water and run down without converting neither to stone nor cobblestone&lt;/p&gt;

&lt;p&gt;&lt;span class=&quot;image-wrap&quot; style=&quot;&quot;&gt;&lt;a id=&quot;272546_thumb&quot; href=&quot;https://bugs.mojang.com/secure/attachment/272546/272546_image-2020-03-07-15-49-34-398.png&quot; title=&quot;image-2020-03-07-15-49-34-398.png&quot; file-preview-type=&quot;image&quot; file-preview-id=&quot;272546&quot; file-preview-title=&quot;image-2020-03-07-15-49-34-398.png&quot;&gt;&lt;img src=&quot;https://bugs.mojang.com/secure/thumbnail/272546/_thumb_272546.png&quot; style=&quot;border: 0px solid black&quot; role=&quot;presentation&quot;/&gt;&lt;/a&gt;&lt;/span&gt;&lt;/p&gt;</comment>
                            <comment id="585721" author="mrjam003" created="Mon, 23 Sep 2019 03:54:10 +0200"  >&lt;p&gt;&lt;b&gt;Affects Minecraft Bedrock 1.12.1&lt;/b&gt;&lt;/p&gt;</comment>
                            <comment id="569489" author="mega_spud" created="Thu, 25 Jul 2019 15:02:40 +0200"  >&lt;p&gt;Reopening as this does still seem to be an issue some of the time.&lt;/p&gt;</comment>
                            <comment id="491881" author="mega_spud" created="Tue, 2 Oct 2018 15:48:37 +0200"  >&lt;p&gt;Cleaning up old tickets:  This ticket has not been updated recently (1 year+) so is being closed as &lt;em&gt;Cannot Reproduce&lt;/em&gt;.  If you feel this is still a valid issue then please comment, or create a new ticket following the &lt;a href=&quot;http://help.mojang.com/customer/portal/articles/801354-writing-helpful-bug-reports-for-minecraft&quot; title=&quot;How To Write helpful bug reports&quot; class=&quot;external-link&quot; target=&quot;_blank&quot; rel=&quot;nofollow noopener&quot;&gt;Issue Guidelines&lt;/a&gt;.&lt;/p&gt;

&lt;p&gt;&lt;b&gt;Quick Links&lt;/b&gt;:&lt;br/&gt;
&#128211; &lt;a href=&quot;http://help.mojang.com/customer/portal/articles/801354-writing-helpful-bug-reports-for-minecraft&quot; title=&quot;How To Write Awesome Tickets! &#128175;&quot; class=&quot;external-link&quot; target=&quot;_blank&quot; rel=&quot;nofollow noopener&quot;&gt;Issue Guidelines&lt;/a&gt; &amp;#8211; &#128172; &lt;a href=&quot;https://www.reddit.com/r/MCPE/&quot; title=&quot;Help From the Minecraft Community &#128377;&quot; class=&quot;external-link&quot; target=&quot;_blank&quot; rel=&quot;nofollow noopener&quot;&gt;Community Support&lt;/a&gt; &amp;#8211; &#128231; &lt;a href=&quot;https://feedback.minecraft.net/&quot; title=&quot;Feedback and Suggestions &#9997;&#65039;&quot; class=&quot;external-link&quot; target=&quot;_blank&quot; rel=&quot;nofollow noopener&quot;&gt;Feedback&lt;/a&gt; &amp;#8211; &#128214; &lt;a href=&quot;http://minecraft.gamepedia.com/Minecraft_Wiki&quot; title=&quot;Official Minecraft Wiki &#127891;&quot; class=&quot;external-link&quot; target=&quot;_blank&quot; rel=&quot;nofollow noopener&quot;&gt;Game Wiki&lt;/a&gt;&lt;/p&gt;</comment>
                    </comments>
                <issuelinks>
                            <issuelinktype id="10102">
                    <name>Duplicate</name>
                                                                <inwardlinks description="is duplicated by">
                                        <issuelink>
            <issuekey id="248673">MCPE-48089</issuekey>
        </issuelink>
            <issuelink>
            <issuekey id="551829">MCPE-179288</issuekey>
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            <issuekey id="313852">MCPE-73342</issuekey>
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            <issuelink>
            <issuekey id="225696">MCPE-41103</issuekey>
        </issuelink>
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                <attachments>
                            <attachment id="536725" name="Instead spread.mp4" size="10309634" author="GoldenHelmet" created="Tue, 6 Jun 2023 03:15:57 +0200"/>
                            <attachment id="536724" name="Lava overtakes water.mp4" size="2847783" author="GoldenHelmet" created="Tue, 6 Jun 2023 03:05:55 +0200"/>
                            <attachment id="136743" name="Water-and-Lava.mcworld" size="150101" author="depressed-pho" created="Fri, 7 Apr 2017 14:07:24 +0200"/>
                            <attachment id="272546" name="image-2020-03-07-15-49-34-398.png" size="588646" author="twilac" created="Sat, 7 Mar 2020 15:49:34 +0100"/>
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