<div dir="ltr"><br><div class="gmail_extra"><br><div class="gmail_quote">On 1 June 2018 at 16:21, Ruslan Synytsky <span dir="ltr"><<a href="mailto:rs@jelastic.com" target="_blank">rs@jelastic.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 Sunny.<br><div class="gmail_extra"><br><div class="gmail_quote"><span class="">On 1 June 2018 at 07:36, Sunny Chan, CLSA <span dir="ltr"><<a href="mailto:sunny.chan@clsa.com" target="_blank">sunny.chan@clsa.com</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex">
<div lang="EN-US">
<div class="m_7913154257255023401gmail-m_8745783528212801861m_2288746132458318163WordSection1">
<p class="MsoNormal"><span style="color:rgb(0,0,102)">Hello,<u></u><u></u></span></p>
<p class="MsoNormal"><span style="color:rgb(0,0,102)"><u></u> <u></u></span></p>
<p class="MsoNormal"><span style="color:rgb(0,0,102)">I have a number of question about the proposed changes for the JEP and I would like to make the following suggestions and comments<u></u><u></u></span></p>
<p class="MsoNormal"><span style="color:rgb(0,0,102)"><u></u> <u></u></span></p>
<p class="m_7913154257255023401gmail-m_8745783528212801861m_2288746132458318163MsoListParagraph"><u></u><span style="color:rgb(0,0,102)"><span>1)<span style="font-style:normal;font-variant:normal;font-weight:normal;font-stretch:normal;font-size:7pt;line-height:normal;font-family:"Times New Roman"">
</span></span></span><u></u><span style="color:rgb(0,0,102)">Are we planning to make this change the default behavior for G1? Or this is an optional switch for people who runs in a container environment?</span></p></div></div></blockquote></span><div>Optional. It will be enough for beginning.</div><span class=""><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex"><div lang="EN-US"><div class="m_7913154257255023401gmail-m_8745783528212801861m_2288746132458318163WordSection1"><p class="m_7913154257255023401gmail-m_8745783528212801861m_2288746132458318163MsoListParagraph"><span style="color:rgb(0,0,102)"><u></u><u></u></span></p>
<p class="m_7913154257255023401gmail-m_8745783528212801861m_2288746132458318163MsoListParagraph"><u></u><span style="color:rgb(0,0,102)"><span>2)<span style="font-style:normal;font-variant:normal;font-weight:normal;font-stretch:normal;font-size:7pt;line-height:normal;font-family:"Times New Roman"">
</span></span></span><u></u><span style="color:rgb(0,0,102)">In a trading systems, sometimes there are period of quiescence and then suddenly a burst of activity towards market close or market event. The loadavg you suggest to “monitor” the activity in the system
only reports up to 14mins and it might not necessary a good measure for this type of applications, especially you would trigger a Full GC</span></p></div></div></blockquote></span><div>I'm sure certain number of workloads can't afford it. Such kind of projects or other mission critical environments simply should not use this option. </div><span class=""><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex"><div lang="EN-US"><div class="m_7913154257255023401gmail-m_8745783528212801861m_2288746132458318163WordSection1"><p class="m_7913154257255023401gmail-m_8745783528212801861m_2288746132458318163MsoListParagraph"><span style="color:rgb(0,0,102)"><u></u><u></u></span></p>
<p class="m_7913154257255023401gmail-m_8745783528212801861m_2288746132458318163MsoListParagraph"><u></u><span style="color:rgb(0,0,102)"><span>3)<span style="font-style:normal;font-variant:normal;font-weight:normal;font-stretch:normal;font-size:7pt;line-height:normal;font-family:"Times New Roman"">
</span></span></span><u></u><span style="color:rgb(0,0,102)">You haven’t fill in the details for “The GCFrequency value is ignored and therefore, i.e., no full collection is triggered, if:”</span></p></div></div></blockquote></span><div>Thanks. It's a missed part. Here are the "if" rules: </div><div><ul style="margin-top:0pt;margin-bottom:0pt"><li dir="ltr" style="list-style-type:disc;font-variant-numeric:normal;font-variant-east-asian:normal;vertical-align:baseline">GCFrequency is zero or below</li><li dir="ltr" style="list-style-type:disc;font-variant-numeric:normal;font-variant-east-asian:normal;vertical-align:baseline">the average load on the host system is above MaxLoadGC. The MaxLoadGC is a dynamically user-defined variable. This check is ignored if MaxLoadGC is zero or below</li><li dir="ltr" style="list-style-type:disc;font-variant-numeric:normal;font-variant-east-asian:normal;vertical-align:baseline">the committed memory is above MinCommitted bytes. MinCommitted is a dynamically user-defined variable. This check is ignored if MinCommitted is zero or below</li><li dir="ltr" style="list-style-type:disc;font-variant-numeric:normal;font-variant-east-asian:normal;vertical-align:baseline">the difference between the current heap capacity and the current heap usage is below MaxOverCommitted bytes. The MaxOverCommitted is a dynamically user-defined variable. This check is ignored if MaxOverCommitted is zero or below </li></ul><div><br></div></div><div>The doc will be updated.</div><span class=""><div> </div><div><span style="color:rgb(0,0,102)">4)<span style="font-variant-numeric:normal;font-variant-east-asian:normal;font-stretch:normal;font-size:7pt;line-height:normal;font-family:"Times New Roman"">
</span></span><u></u><span style="color:rgb(0,0,102)">If we are trigging full GC with this we should make sure the GC reason is populated and log properly in the GC log so we can track it down.</span></div></span><div>Good point. </div><span class=""><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex"><div lang="EN-US"><div class="m_7913154257255023401gmail-m_8745783528212801861m_2288746132458318163WordSection1"><p class="m_7913154257255023401gmail-m_8745783528212801861m_2288746132458318163MsoListParagraph"><span style="color:rgb(0,0,102)"><u></u><u></u></span></p>
<p class="m_7913154257255023401gmail-m_8745783528212801861m_2288746132458318163MsoListParagraph"><u></u><span style="color:rgb(0,0,102)"><span>5)<span style="font-style:normal;font-variant:normal;font-weight:normal;font-stretch:normal;font-size:7pt;line-height:normal;font-family:"Times New Roman"">
</span></span></span><u></u><span style="color:rgb(0,0,102)">I have not heard of J9 Gencon/Shenandoah providing similar functionality. Can you point me to further documentation on which feature you model upon?</span></p></div></div></blockquote></span><div><span class="m_7913154257255023401gmail-il" style="color:rgb(34,34,34);font-family:arial,sans-serif;font-size:small;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;text-decoration-style:initial;text-decoration-color:initial">What we know so far that OpenJ9</span><span style="color:rgb(34,34,34);font-family:arial,sans-serif;font-size:small;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);text-decoration-style:initial;text-decoration-color:initial;float:none;display:inline"><span> </span>provides </span></div><div><ul><li><a href="https://www.ibm.com/support/knowledgecenter/en/SSYKE2_8.0.0/com.ibm.java.vm.80.doc/docs/xxidletuningcompactonidle.html" target="_blank">-XX:+IdleTuningCompactOnIdle</a> -<wbr> this option controls garbage collection processing with compaction when the status of the JVM is set to idle<br></li><li>and <a href="https://www.ibm.com/support/knowledgecenter/en/SSYKE2_8.0.0/com.ibm.java.vm.80.doc/docs/xsoftmx.html" target="_blank">-Xsoftmx</a> - this option sets a "soft" maximum limit for the initial size of the Java™ heap. </li></ul>We have not tested it yet, but the idea looks similar. Do we have anyone in the group involved in OpenJ9 to confirm or refute this statement? </div></div></div></div></blockquote><div><div style="color:rgb(34,34,34);font-family:arial,sans-serif;font-size:small;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);text-decoration-style:initial;text-decoration-color:initial">It's getting more attention. A new mentioning of the implementation in OpenJ9 - <a href="https://dzone.com/storage/assets/9318874-dzone2018-researchguide-java.pdf">DZone Java 2018: FEATURES, IMPROVEMENTS, & UPDATES</a> (Page 31).</div></div><div><br></div><div><i> You can also
specify -XX:+IdleTuningGcOnIdle on the command line. When
set, OpenJ9 determines whether an application is idle based on CPU
utilization and other internal heuristics. When an idle state is recognized,
a GC cycle runs if there is significant garbage in the heap and
releases unused memory back to the operating system. </i><br></div><div><br></div><div><br></div><div> </div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div dir="ltr"><div class="gmail_extra"><div class="gmail_quote"><div><br></div><div>Thank you</div><span class=""><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex"><div lang="EN-US"><div class="m_7913154257255023401gmail-m_8745783528212801861m_2288746132458318163WordSection1"><p class="m_7913154257255023401gmail-m_8745783528212801861m_2288746132458318163MsoListParagraph"><span style="color:rgb(0,0,102)"><u></u><u></u></span></p>
<p class="MsoNormal"><span style="color:rgb(0,0,102)"><u></u> <u></u></span></p>
<p class="MsoNormal"><span style="color:rgb(0,0,102)">Thanks.<u></u><u></u></span></p>
<p class="MsoNormal"><span style="color:rgb(0,0,102)"><u></u> <u></u></span></p>
<p class="MsoNormal" style="line-height:110%"><b><span style="font-size:9pt;line-height:110%;color:rgb(0,0,102)">Sunny Chan<u></u><u></u></span></b></p>
<p class="MsoNormal" style="line-height:110%"><b><span style="font-size:9pt;line-height:110%;color:rgb(0,0,102)">Senior Lead Engineer, Executive Services<u></u><u></u></span></b></p>
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</blockquote></span></div><span class="HOEnZb"><font color="#888888"><br><br clear="all"><div><br></div>-- <br><div class="m_7913154257255023401gmail-m_8745783528212801861gmail_signature"><div dir="ltr"><div><div dir="ltr"><div style="font-size:12.8px"><div dir="ltr"><div dir="ltr"><div dir="ltr"><div dir="ltr"><div dir="ltr"><div dir="ltr"><div dir="ltr"><div dir="ltr"><div style="font-family:"Times New Roman""><span style="font-family:Calibri,sans-serif;font-size:15px">Ruslan</span><br style="font-family:Calibri,sans-serif;font-size:15px"><span style="font-family:Calibri,sans-serif;font-size:15px">CEO @ </span><span style="font-family:Calibri,sans-serif;font-size:15px"><a href="https://jelastic.com/" style="color:rgb(17,85,204)" target="_blank">Jelastic</a></span></div></div></div></div></div></div></div></div></div></div></div></div></div></div>
</font></span></div></div>
</blockquote></div><br><br clear="all"><div><br></div>-- <br><div class="gmail_signature" data-smartmail="gmail_signature"><div dir="ltr"><div><div dir="ltr"><div style="font-size:12.8px"><div dir="ltr"><div dir="ltr"><div dir="ltr"><div dir="ltr"><div dir="ltr"><div dir="ltr"><div dir="ltr"><div dir="ltr"><div style="font-family:"Times New Roman""><span style="font-family:Calibri,sans-serif;font-size:15px">Ruslan</span><br style="font-family:Calibri,sans-serif;font-size:15px"><span style="font-family:Calibri,sans-serif;font-size:15px">CEO @ </span><span style="font-family:Calibri,sans-serif;font-size:15px"><a href="https://jelastic.com/" style="color:rgb(17,85,204)" target="_blank">Jelastic</a></span></div></div></div></div></div></div></div></div></div></div></div></div></div></div>
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