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Hi Roman,<br>
<br>
<div class="moz-cite-prefix">On 2017-10-17 23:34, Roman Kennke
wrote:<br>
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<div class="moz-cite-prefix">Am 17.10.2017 um 23:10 schrieb Roman
Kennke:<br>
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<p>The SuspendibleThreadSet API for synchronizing any non-Java
thread with safepoints currently resides under gc/g1. It is
very useful for other GCs too (in particular, Shenandoah
does use it too), so I wanted to move it to a common
location like gc/common. Then Kim Barrett commented that it
might actually be useful for other threads outside GC land
and to put it under runtime/. So I did:</p>
<p><a moz-do-not-send="true"
href="http://cr.openjdk.java.net/%7Erkennke/8189276/webrev.00/">http://cr.openjdk.java.net/~rkennke/8189276/webrev.00/</a></p>
<p>I also added a generic hook to call the STS from safepoint
sync/desync, which is consequently used by G1 now. In other
words, the CollectedHeap API that Erik Ö introduced is no
longer used by G1. Only CMS still uses that API because it
has its own way to sync with safepoints. I filed <a
moz-do-not-send="true"
href="https://bugs.openjdk.java.net/browse/JDK-8189364">another
bug</a> for this. Although I have my doubt it will ever be
fixed. This seems to have been very carefully evolved (to
put it positive), and the risk of breaking it is relatively
high, and thus doesn't seem worth the struggle to make it
fit the STS.<br>
</p>
<p>Issue:<br>
<a moz-do-not-send="true"
href="https://bugs.openjdk.java.net/browse/JDK-8189276">https://bugs.openjdk.java.net/browse/JDK-8189276</a></p>
<p>What do you think? Ok to go in?</p>
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Replying to myself here.<br>
I must admit that I am a bit reluctant to expose it to runtime/
unless there's a specific need for it. So maybe go back to the
original plan to move it into gc/common and leave all the rest
alone for now? What do others think?<br>
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<br>
Sorry, forgot to add something. One reason why we originally
wanted to move it to gc/common (a new directory) instead of the
existing gc/shared was that Erik H objected that gc/shared would
be built into the minimal VM, and we probably wouldn't want that
unless needed. However, moving it to runtime/ (without actual
need), would achieve just that. So unless we can name an actual
thread that would benefit from synchronizing using the STS, I
suggest to leave the STS code in gc/common for now?<br>
<br>
That would be:<br>
<a moz-do-not-send="true"
href="http://cr.openjdk.java.net/%7Erkennke/8189276/webrev.01/">http://cr.openjdk.java.net/~rkennke/8189276/webrev.01/</a><br>
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<br>
We had some internal discussions, and the conclusion seems to be
that we would like to not have a new gc/common directory for
build-only purposes, but rather put it in gc/shared and explicitly
mark files we do not want to have compiled in minimal VM in the
make/hotspot/lib/JvmFeatures.gmk build file. You can remove files
from the minimal VM build by explicitly adding files to an exclude
list in that file.<br>
<br>
133: JVM_EXCLUDE_FILES += \<br>
134: concurrentGCThread.cpp \<br>
+++ add your files here<br>
135: plab.cpp<br>
<br>
I tend to agree that avoiding the new gc/common directory is
probably a win right now. Hope you agree with this.<br>
<br>
Thanks,<br>
/Erik<br>
<br>
<blockquote
cite="mid:3a72da30-b74f-a65e-1f06-adefb0e610c8@redhat.com"
type="cite"> Roman<br>
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