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Marge Bot pushed to branch master at <a href="https://gitlab.haskell.org/ghc/ghc">Glasgow Haskell Compiler / GHC</a>
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Commits:
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<ul>
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<strong style="font-weight: bold;"><a href="https://gitlab.haskell.org/ghc/ghc/-/commit/960c8d47f064644617a605b1225a18e9350be995">960c8d47</a></strong>
<div>
<span> by Teo Camarasu </span> <i> at 2024-02-29T21:26:20-05:00 </i>
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<pre class="commit-message" style='white-space: pre-wrap; display: block; font-size: 14px; color: #333238; position: relative; font-family: var(--default-mono-font, "GitLab Mono"),"JetBrains Mono","Menlo","DejaVu Sans Mono","Liberation Mono","Consolas","Ubuntu Mono","Courier New","andale mono","lucida console",monospace; word-break: break-all; word-wrap: break-word; background-color: #fbfafd; border-radius: 2px; margin: 0; padding: 8px 12px; border: 1px solid #dcdcde;'>Reduce AtomicModifyIORef increment count

This test leads to a lot of contention when N>2 and becomes very slow. Let's reduce the amount of work we do to compensate. Resolves #24490
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2 changed files:
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<a href="#b6f3942d2a2641e9f28754163d437ea1dcd1dc37">
libraries/base/tests/AtomicModifyIORef.hs
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<a href="#99a905aa4e33986c9efdffdf47c701690d40c19f">
libraries/base/tests/AtomicModifyIORef.stdout
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Changes:
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<li id="b6f3942d2a2641e9f28754163d437ea1dcd1dc37">
<a href="https://gitlab.haskell.org/ghc/ghc/-/commit/960c8d47f064644617a605b1225a18e9350be995#b6f3942d2a2641e9f28754163d437ea1dcd1dc37"><strong style="font-weight: bold;">libraries/base/tests/AtomicModifyIORef.hs</strong></a>
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<td class="line_content match" style="color: rgba(31,30,36,0.24); padding: inherit;" bgcolor="#fbfafd">@@ -5,7 +5,7 @@ import Data.IORef</td>
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<td class="line_content" style="padding: inherit;"><pre style='display: block; font-size: 14px; color: #333238; position: relative; font-family: var(--default-mono-font, "GitLab Mono"),"JetBrains Mono","Menlo","DejaVu Sans Mono","Liberation Mono","Consolas","Ubuntu Mono","Courier New","andale mono","lucida console",monospace; word-break: break-all; word-wrap: break-word; background-color: inherit; border-radius: 2px; margin: 0; padding: 0; border: inherit solid #dcdcde;'> <span id="LC5" class="line" lang="haskell"><span class="n" style="color: #333;">main</span> <span class="o" style="font-weight: 600;">::</span> <span class="kt" style="color: #458; font-weight: 600;">IO</span> <span class="nb" style="color: #0086b3;">()</span></span>
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<td class="new_line diff-line-num" data-linenumber="6" style="width: 35px; color: rgba(31,30,36,0.24); border-right-width: 1px; border-right-color: #ececef; border-right-style: solid; padding: inherit;" align="right" bgcolor="#fbfafd">
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<td class="line_content" style="padding: inherit;"><pre style='display: block; font-size: 14px; color: #333238; position: relative; font-family: var(--default-mono-font, "GitLab Mono"),"JetBrains Mono","Menlo","DejaVu Sans Mono","Liberation Mono","Consolas","Ubuntu Mono","Courier New","andale mono","lucida console",monospace; word-break: break-all; word-wrap: break-word; background-color: inherit; border-radius: 2px; margin: 0; padding: 0; border: inherit solid #dcdcde;'> <span id="LC6" class="line" lang="haskell"><span class="n" style="color: #333;">main</span> <span class="o" style="font-weight: 600;">=</span> <span class="kr" style="font-weight: 600;">do</span></span>
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<td class="old_line diff-line-num" data-linenumber="7" style="width: 35px; color: rgba(31,30,36,0.24); border-right-width: 1px; border-right-color: #ececef; border-right-style: solid; padding: inherit;" align="right" bgcolor="#fbfafd">
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<td class="new_line diff-line-num" data-linenumber="7" style="width: 35px; color: rgba(31,30,36,0.24); border-right-width: 1px; border-right-color: #ececef; border-right-style: solid; padding: inherit;" align="right" bgcolor="#fbfafd">
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<td class="line_content" style="padding: inherit;"><pre style='display: block; font-size: 14px; color: #333238; position: relative; font-family: var(--default-mono-font, "GitLab Mono"),"JetBrains Mono","Menlo","DejaVu Sans Mono","Liberation Mono","Consolas","Ubuntu Mono","Courier New","andale mono","lucida console",monospace; word-break: break-all; word-wrap: break-word; background-color: inherit; border-radius: 2px; margin: 0; padding: 0; border: inherit solid #dcdcde;'> <span id="LC7" class="line" lang="haskell">    <span class="kr" style="font-weight: 600;">let</span> <span class="n" style="color: #333;">nThreads</span> <span class="o" style="font-weight: 600;">=</span> <span class="mi" style="color: #099;">10</span></span>
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<td class="old_line diff-line-num old" data-linenumber="8" style="width: 35px; color: rgba(31,30,36,0.24); border-right-width: 1px; border-right-color: #fac5cd; border-right-style: solid; padding: inherit;" align="right" bgcolor="#f9d7dc">
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<td class="new_line diff-line-num old" data-linenumber="8" style="width: 35px; color: rgba(31,30,36,0.24); border-right-width: 1px; border-right-color: #fac5cd; border-right-style: solid; padding: inherit;" align="right" bgcolor="#f9d7dc">
 
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<td class="line_content old" style="padding: inherit;" bgcolor="#fbe9eb"><pre style='display: block; font-size: 14px; color: #333238; position: relative; font-family: var(--default-mono-font, "GitLab Mono"),"JetBrains Mono","Menlo","DejaVu Sans Mono","Liberation Mono","Consolas","Ubuntu Mono","Courier New","andale mono","lucida console",monospace; word-break: break-all; word-wrap: break-word; background-color: inherit; border-radius: 2px; margin: 0; padding: 0; border: inherit solid #dcdcde;'>-<span id="LC8" class="line" lang="haskell">        <span class="n" style="color: #333;">nIncrs</span> <span class="o" style="font-weight: 600;">=</span> <span class="mi" style="color: #099;">10000<span class="idiff left right deletion" style="background-color: #fac5cd;">000</span></span></span>
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<td class="old_line diff-line-num new" data-linenumber="9" style="width: 35px; color: rgba(31,30,36,0.24); border-right-width: 1px; border-right-color: #c7f0d2; border-right-style: solid; padding: inherit;" align="right" bgcolor="#ddfbe6">
 
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<td class="new_line diff-line-num new" data-linenumber="8" style="width: 35px; color: rgba(31,30,36,0.24); border-right-width: 1px; border-right-color: #c7f0d2; border-right-style: solid; padding: inherit;" align="right" bgcolor="#ddfbe6">
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<td class="line_content new" style="padding: inherit;" bgcolor="#ecfdf0"><pre style='display: block; font-size: 14px; color: #333238; position: relative; font-family: var(--default-mono-font, "GitLab Mono"),"JetBrains Mono","Menlo","DejaVu Sans Mono","Liberation Mono","Consolas","Ubuntu Mono","Courier New","andale mono","lucida console",monospace; word-break: break-all; word-wrap: break-word; background-color: inherit; border-radius: 2px; margin: 0; padding: 0; border: inherit solid #dcdcde;'>+<span id="LC8" class="line" lang="haskell">        <span class="n" style="color: #333;">nIncrs</span> <span class="o" style="font-weight: 600;">=</span> <span class="mi" style="color: #099;">10000</span></span>
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<td class="new_line diff-line-num" data-linenumber="9" style="width: 35px; color: rgba(31,30,36,0.24); border-right-width: 1px; border-right-color: #ececef; border-right-style: solid; padding: inherit;" align="right" bgcolor="#fbfafd">
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<td class="line_content" style="padding: inherit;"><pre style='display: block; font-size: 14px; color: #333238; position: relative; font-family: var(--default-mono-font, "GitLab Mono"),"JetBrains Mono","Menlo","DejaVu Sans Mono","Liberation Mono","Consolas","Ubuntu Mono","Courier New","andale mono","lucida console",monospace; word-break: break-all; word-wrap: break-word; background-color: inherit; border-radius: 2px; margin: 0; padding: 0; border: inherit solid #dcdcde;'> <span id="LC9" class="line" lang="haskell"></span>
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<td class="new_line diff-line-num" data-linenumber="10" style="width: 35px; color: rgba(31,30,36,0.24); border-right-width: 1px; border-right-color: #ececef; border-right-style: solid; padding: inherit;" align="right" bgcolor="#fbfafd">
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<td class="line_content" style="padding: inherit;"><pre style='display: block; font-size: 14px; color: #333238; position: relative; font-family: var(--default-mono-font, "GitLab Mono"),"JetBrains Mono","Menlo","DejaVu Sans Mono","Liberation Mono","Consolas","Ubuntu Mono","Courier New","andale mono","lucida console",monospace; word-break: break-all; word-wrap: break-word; background-color: inherit; border-radius: 2px; margin: 0; padding: 0; border: inherit solid #dcdcde;'> <span id="LC10" class="line" lang="haskell">    <span class="n" style="color: #333;">ref</span> <span class="o" style="font-weight: 600;"><-</span> <span class="n" style="color: #333;">newIORef</span> <span class="p">(</span><span class="mi" style="color: #099;">42</span> <span class="o" style="font-weight: 600;">::</span> <span class="kt" style="color: #458; font-weight: 600;">Int</span><span class="p">)</span></span>
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<td class="old_line diff-line-num" data-linenumber="11" style="width: 35px; color: rgba(31,30,36,0.24); border-right-width: 1px; border-right-color: #ececef; border-right-style: solid; padding: inherit;" align="right" bgcolor="#fbfafd">
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<td class="line_content" style="padding: inherit;"><pre style='display: block; font-size: 14px; color: #333238; position: relative; font-family: var(--default-mono-font, "GitLab Mono"),"JetBrains Mono","Menlo","DejaVu Sans Mono","Liberation Mono","Consolas","Ubuntu Mono","Courier New","andale mono","lucida console",monospace; word-break: break-all; word-wrap: break-word; background-color: inherit; border-radius: 2px; margin: 0; padding: 0; border: inherit solid #dcdcde;'> <span id="LC11" class="line" lang="haskell">    <span class="n" style="color: #333;">dones</span> <span class="o" style="font-weight: 600;"><-</span> <span class="n" style="color: #333;">replicateM</span> <span class="n" style="color: #333;">nThreads</span> <span class="o" style="font-weight: 600;">$</span> <span class="kr" style="font-weight: 600;">do</span></span>
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<a href="https://gitlab.haskell.org/ghc/ghc/-/commit/960c8d47f064644617a605b1225a18e9350be995#99a905aa4e33986c9efdffdf47c701690d40c19f"><strong style="font-weight: bold;">libraries/base/tests/AtomicModifyIORef.stdout</strong></a>
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<td class="old_line diff-line-num" data-linenumber="10" style="width: 35px; color: rgba(31,30,36,0.24); border-right-width: 1px; border-right-color: #ececef; border-right-style: solid; padding: inherit;" align="right" bgcolor="#fbfafd">
10
</td>
<td class="new_line diff-line-num" data-linenumber="10" style="width: 35px; color: rgba(31,30,36,0.24); border-right-width: 1px; border-right-color: #ececef; border-right-style: solid; padding: inherit;" align="right" bgcolor="#fbfafd">
10
</td>
<td class="line_content" style="padding: inherit;"><pre style='display: block; font-size: 14px; color: #333238; position: relative; font-family: var(--default-mono-font, "GitLab Mono"),"JetBrains Mono","Menlo","DejaVu Sans Mono","Liberation Mono","Consolas","Ubuntu Mono","Courier New","andale mono","lucida console",monospace; word-break: break-all; word-wrap: break-word; background-color: inherit; border-radius: 2px; margin: 0; padding: 0; border: inherit solid #dcdcde;'> <span id="LC10" class="line" lang="plaintext">.</span>
</pre></td>
</tr>
<tr class="line_holder old" style="line-height: 1.6;">
<td class="old_line diff-line-num old" data-linenumber="11" style="width: 35px; color: rgba(31,30,36,0.24); border-right-width: 1px; border-right-color: #fac5cd; border-right-style: solid; padding: inherit;" align="right" bgcolor="#f9d7dc">
11
</td>
<td class="new_line diff-line-num old" data-linenumber="11" style="width: 35px; color: rgba(31,30,36,0.24); border-right-width: 1px; border-right-color: #fac5cd; border-right-style: solid; padding: inherit;" align="right" bgcolor="#f9d7dc">
 
</td>
<td class="line_content old" style="padding: inherit;" bgcolor="#fbe9eb"><pre style='display: block; font-size: 14px; color: #333238; position: relative; font-family: var(--default-mono-font, "GitLab Mono"),"JetBrains Mono","Menlo","DejaVu Sans Mono","Liberation Mono","Consolas","Ubuntu Mono","Courier New","andale mono","lucida console",monospace; word-break: break-all; word-wrap: break-word; background-color: inherit; border-radius: 2px; margin: 0; padding: 0; border: inherit solid #dcdcde;'>-<span id="LC11" class="line" lang="plaintext">1000<span class="idiff left right deletion" style="background-color: #fac5cd;">000</span>42</span></pre></td>
</tr>
<tr class="line_holder new" style="line-height: 1.6;">
<td class="old_line diff-line-num new" data-linenumber="12" style="width: 35px; color: rgba(31,30,36,0.24); border-right-width: 1px; border-right-color: #c7f0d2; border-right-style: solid; padding: inherit;" align="right" bgcolor="#ddfbe6">
 
</td>
<td class="new_line diff-line-num new" data-linenumber="11" style="width: 35px; color: rgba(31,30,36,0.24); border-right-width: 1px; border-right-color: #c7f0d2; border-right-style: solid; padding: inherit;" align="right" bgcolor="#ddfbe6">
11
</td>
<td class="line_content new" style="padding: inherit;" bgcolor="#ecfdf0"><pre style='display: block; font-size: 14px; color: #333238; position: relative; font-family: var(--default-mono-font, "GitLab Mono"),"JetBrains Mono","Menlo","DejaVu Sans Mono","Liberation Mono","Consolas","Ubuntu Mono","Courier New","andale mono","lucida console",monospace; word-break: break-all; word-wrap: break-word; background-color: inherit; border-radius: 2px; margin: 0; padding: 0; border: inherit solid #dcdcde;'>+<span id="LC11" class="line" lang="plaintext">100042</span></pre></td>
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