<div dir="ltr">Thanks, Paul. We're definitely going to re-evaluate G1 with a more modern JDK, but to do it for real, we need to re-evaluate it alongside something that can run CMS in a production setting. Getting a JDK and our codebase to the point where that is possible at Google is quite a bit of work, so it would be a lot of work for us to rush to do it for 9 or 10 and then start again for 10/11. <div><br></div><div>(The work for 9/10 would help us for 11, but there would be quite a bit of extra work, as well.)<div><br></div><div>In short: "unlikely" is definitely good news for us. :) We'll watch this space for updates, in case that changes.<br><div><br></div><div>Jeremy</div></div></div></div><div class="gmail_extra"><br><div class="gmail_quote">On Tue, Jan 30, 2018 at 4:07 PM, Paul Su <span dir="ltr"><<a href="mailto:paul.su@oracle.com" target="_blank">paul.su@oracle.com</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div style="word-wrap:break-word"><div>Hi Jeremy, Wessam,</div><div><br></div><div> At this time, removal of CMS is still under consideration for JDK 11 but unlikely to happen within that timeframe. However, there were significant performance improvements to G1 in JDK 9 and 10, so it may be worthwhile to evaluate those with your use cases. As always, any feedback is welcome and appreciated. </div><div><br></div><div>Thanks,</div><div>Paul</div><div><br><blockquote type="cite"><div bgcolor="#FFFFFF" text="#000000"><div class="m_-6697932000766208919moz-forward-container"><br><table class="m_-6697932000766208919moz-email-headers-table" border="0" cellspacing="0" cellpadding="0">
<tbody>
<tr>
<th nowrap valign="BASELINE" align="RIGHT">Subject:
</th>
<td>Re: Expected JDK version of when CMS code is suppose to
be dropped, is it JDK11?</td>
</tr>
<tr>
<th nowrap valign="BASELINE" align="RIGHT">Date: </th>
<td>Tue, 30 Jan 2018 10:25:27 -0800</td>
</tr>
<tr>
<th nowrap valign="BASELINE" align="RIGHT">From: </th>
<td>Jeremy Manson <a class="m_-6697932000766208919moz-txt-link-rfc2396E" href="mailto:jeremymanson@google.com" target="_blank"><jeremymanson@google.com></a></td>
</tr>
<tr>
<th nowrap valign="BASELINE" align="RIGHT">To: </th>
<td>Wessam Hassanein <a class="m_-6697932000766208919moz-txt-link-rfc2396E" href="mailto:wessam@google.com" target="_blank"><wessam@google.com></a></td>
</tr>
<tr>
<th nowrap valign="BASELINE" align="RIGHT">CC: </th>
<td><a class="m_-6697932000766208919moz-txt-link-abbreviated" href="mailto:hotspot-gc-dev@openjdk.java.net" target="_blank">hotspot-gc-dev@openjdk.java.<wbr>net</a> <a href="http://openjdk.java.net" target="_blank">openjdk.java.net</a>
<a class="m_-6697932000766208919moz-txt-link-rfc2396E" href="mailto:hotspot-gc-dev@openjdk.java.net" target="_blank"><hotspot-gc-dev@openjdk.java.<wbr>net></a></td>
</tr>
</tbody>
</table><div><div class="h5">
<br>
<br>
<div dir="ltr">Hi folks,
<div><br>
</div>
<div>Wessam's question is pretty important to our planning.</div>
<div><br>
</div>
<div>As many of you know, we were unable to get the G1 collector
as it shipped with JDK 8 to work well with our services. We
want to try a newer branch.</div>
<div><br>
</div>
<div>However, it also takes us a lot of work to make a JDK
workable for internal use. We have to patch it to work with
our systems, and we have to make a whole lot of tests and
infrastructure functional.</div>
<div><br>
</div>
<div>We'd rather not rush to get out a Java version that will
stop being supported in a few months. Java 9 has already seen
its last release, and we aren't really all that close to
making it work for the kinds of systems that actually care
about the GC they are using. We are debating whether to try
to continue to make Java 9 work, move to Java 10, or to skip
both and go with Java 11, which will see long term support.</div>
<div><br>
</div>
<div>(If we went to 11, we'd continue to experiment with 9 and
10, but we wouldn't push it hard.)</div>
<div><br>
</div>
<div>In order to switch to G1, we need a release where our
services can compare a recent G1 with CMS. If the last
release with both of them is Java 10, then we need to work on
Java 10, in spite of its September expiration date. If the
last release with both of them is Java 11, then we will have a
lot more breathing room for the G1 migration, and we can
target that instead.</div>
<div><br>
</div>
<div>So, it would be really helpful if someone could chime in
with more information about the timeline for CMS removal. Is
it likely to be before the door closes for the Java 11
release?</div>
<div><br>
</div>
<div>Thanks!</div>
<div><br>
</div>
<div>Jeremy</div>
</div>
<div class="gmail_extra"><br>
<div class="gmail_quote">On Fri, Jan 26, 2018 at 12:36 PM,
Wessam Hassanein <span dir="ltr"><<a href="mailto:wessam@google.com" target="_blank">wessam@google.com</a>></span>
wrote:<br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
<div dir="ltr">Hi All,
<div><br>
</div>
<div>Per JEP 291( <a href="http://openjdk.java.net/jeps/291" rel="noreferrer" style="color:rgb(17,85,204);font-family:arial,sans-serif;font-size:12.8px;font-style:normal;font-variant-ligatures:normal;font-variant-caps:normal;font-weight:400;letter-spacing:normal;text-align:start;text-indent:0px;text-transform:none;white-space:normal;word-spacing:0px;background-color:rgb(255,255,255)" target="_blank">http://openjdk.java.net/j<wbr>eps/291</a>)
the CMS collector was deprecated but there was no clear
date of when it is expected for the CMS code to be
dropped. I see code refactoring in JDK10 JEP 304 (<a href="http://openjdk.java.net/jeps/304" target="_blank">http://openjdk.java.net/jeps/<wbr>304</a>) and
I am wondering whether CMS is planned to be dropped in
JDK11 or when it is expected to be dropped?</div>
<div><br>
</div>
<div>Thanks,</div>
<div><br>
</div>
<div>Wessam Hassanein</div>
<div>Google GC TL</div>
<div><br>
</div>
</div>
</blockquote>
</div>
<br>
</div>
</div></div></div>
</div>
</blockquote></div><br></div></blockquote></div><br></div>