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Hi Jonathan, </div>
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There is an open bug related to missing threads in JFR [1]. It could be the issue, or it might something new for VT. <span style="color: rgb(0, 0, 0); font-family: Calibri, Arial, Helvetica, sans-serif; font-size: 12pt;">We will take a look. Thanks for reporting. </span><span style="color: rgb(0, 0, 0); font-family: Calibri, Arial, Helvetica, sans-serif; font-size: 12pt;">Today
we record OS thread in the thread struct[2], maybe we could add the carrier/platform thread as well. </span><span style="color: rgb(0, 0, 0); font-family: Calibri, Arial, Helvetica, sans-serif; font-size: 12pt;">It would allow JMC to render VTs in the thread
view.</span></div>
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Erik</div>
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[1] <a href="https://bugs.openjdk.org/browse/JDK-8304033" style="margin:0px;background-color:rgb(255, 255, 255)" class="ContentPasted2">https://bugs.openjdk.org/browse/JDK-8304033</a></div>
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[2] <a href="https://github.com/openjdk/jdk/blob/master/src/hotspot/share/jfr/metadata/metadata.xml#L1207" id="LPlnkOWALinkPreview_2">https://github.com/openjdk/jdk/blob/master/src/hotspot/share/jfr/metadata/metadata.xml#L1207</a><br>
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Erik</div>
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<div id="divRplyFwdMsg" dir="ltr"><font face="Calibri, sans-serif" style="font-size:11pt" color="#000000"><b>From:</b> hotspot-jfr-dev <hotspot-jfr-dev-retn@openjdk.org> on behalf of Alan Bateman <Alan.Bateman@oracle.com><br>
<b>Sent:</b> Wednesday, March 22, 2023 9:21 PM<br>
<b>To:</b> Jonathan Ross <jonathan.ross@cjug.org><br>
<b>Cc:</b> hotspot-jfr-dev <hotspot-jfr-dev@openjdk.java.net>; loom-dev@openjdk.org <loom-dev@openjdk.org><br>
<b>Subject:</b> Re: JFR integration</font>
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<div class="BodyFragment"><font size="2"><span style="font-size:11pt;">
<div class="PlainText">On 22/03/2023 19:16, Jonathan Ross wrote:<br>
> Okay, it must be something else causing the jfr problem, I'll contact <br>
> jfr-dev as you suggest, thanks for that suggestion.<br>
><br>
> Can you comment on jfr events not including information about the <br>
> carrier thread? Is there any particular reason not to (want to) <br>
> include platform thread information? I, for one, would like to be <br>
> able to see the underlying fork-join scheduler at work in flight <br>
> recordings.<br>
The scheduler threads are distinct and you may see some events committed <br>
on those threads. What would you do with the linkage if it was in the <br>
recording?<br>
<br>
<br>
><br>
> A second, somewhat related question: is it possible to use multiple <br>
> distinct carrier thread pools, with different parallelism? (Perhaps <br>
> there is some magic around creating virtual threads from within a <br>
> forkjoin task?)<br>
><br>
Not at this time. It will take time for the eco system to get used to <br>
virtual threads and in the future we can evaluate if are compelling <br>
reasons to allow for custom schedulers.<br>
<br>
-Alan<br>
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