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<div class="moz-cite-prefix">On 5/6/2015 4:34 AM, Tangwei (Euler
Architecture & Design Dept) wrote:<br>
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<p class="MsoNormal"><span lang="EN-US">Hi All, <o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"> As a newbie in GC, I
found some discussion on object copying order in following
slides: breadth vs. depth.
<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">It mentioned that <i>“Any
static policy will hurt some applications and help
others”.
</i>After searching, there is a BZ shows <o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">the object copying order
has been switched from breadth to depth for ParallelGC in
OpenJDK, please correct if I am wrong.
<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">Anyone can help to
confirm if all GC in OpenJDK use depth first copying now?
</span></p>
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<br>
No, not all the GC's use depth first copying.<br>
<br>
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cite="mid:C8D1E566CC4CA845813731FB6FD5C5300108B512@SZXEMI503-MBX.china.huawei.com"
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<p class="MsoNormal"><span lang="EN-US"><o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">Is there any performance
consideration to choose depth first instead of controlling
by option?</span></p>
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<br>
Yes, there is a performance cost to optionally using depth-first or
breadth-first.<br>
ParallelGC used to have such an option. It made the code harder to
maintain and,<br>
as far as I can recall, there was very little use of the option. We
removed the<br>
it. I recall maybe 1 complaint about it.<br>
<br>
Jon<br>
<br>
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<p class="MsoNormal"><span lang="EN-US"><o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"><a
moz-do-not-send="true"
href="http://www.oracle.com/technetwork/server-storage/ts-6434-159339.pdf">http://www.oracle.com/technetwork/server-storage/ts-6434-159339.pdf</a><o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span
style="font-family:"Arial","sans-serif";color:black"
lang="EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span
style="font-family:"Arial","sans-serif";color:black"
lang="EN-US"><a moz-do-not-send="true"
href="https://bugs.openjdk.java.net/browse/JDK-6450584">https://bugs.openjdk.java.net/browse/JDK-6450584</a></span><span
style="font-family:"Arial","sans-serif""
lang="EN-US">:
<span style="color:black">Improve object copying order in
parallel scavenge</span></span><span lang="EN-US"><o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">Regards!<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">wei <o:p></o:p></span></p>
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