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Ramki,<br>
<br>
On 2011-11-14 20:32, Srinivas Ramakrishna wrote:
<blockquote
cite="mid:CABzyjym+XcbDArUOPdpqev=a-vdTy5gzqJUtnfPHyPfK9AN+=A@mail.gmail.com"
type="cite"><br>
Thanks, Bengt, for the super-quick turnaround!! A comment below on
the choice of <= 0 for the option value....<br>
</blockquote>
<br>
Thanks for the review! See comments below.<br>
<br>
<blockquote
cite="mid:CABzyjym+XcbDArUOPdpqev=a-vdTy5gzqJUtnfPHyPfK9AN+=A@mail.gmail.com"
type="cite">
<div class="gmail_quote">On Mon, Nov 14, 2011 at 1:25 AM, Bengt
Rutisson <span dir="ltr"><<a moz-do-not-send="true"
href="mailto:bengt.rutisson@oracle.com">bengt.rutisson@oracle.com</a>></span>
wrote:<br>
<blockquote class="gmail_quote" style="margin: 0pt 0pt 0pt
0.8ex; border-left: 1px solid rgb(204, 204, 204);
padding-left: 1ex;"><br>
Hi all,<br>
<br>
Can I have a couple of reviews for this small change?<br>
<a moz-do-not-send="true"
href="http://cr.openjdk.java.net/%7Ebrutisso/7110718/webrev.01/"
target="_blank">http://cr.openjdk.java.net/~brutisso/7110718/webrev.01/</a><br>
<br>
It is a fix for the issue that Ramki reported recently.
MarkSweepAlwaysCompactCount is used for division and Hotspot
crashes if it is set to 0.<br>
<br>
I choose to log an error and exit the VM if someone tries to
start with -XX:MarkSweepAlwaysCompactCount=0. An alternative
is to just log a warning and set it to 1.<br>
<br>
I prefer the error way since it is not really clear what one
wants to achieve with MarkSweepAlwaysCompactCount=0. Always do
full compactions or never do full compactions? So I am not
convinced that 1 is an appropriate value.<br>
<br>
Also, since the VM, up until now, has crashed if someone tried
-XX:MarkSweepAlwaysCompactCount=0 I think we can be sure that
there are no customers that are running with that setting. It
should be safe to forbid it.<br>
</blockquote>
<div><br>
I agree with that statement. However, given that the value 0
was producing crashes, proving that no production code would
have been using that setting,<br>
and based on yr comment above that the 0 value could as well
have been used to denote "never force full compaction", it
seems as though an alternative to exiting with<br>
an error, is now to define all values <=0 to mean "never
_force_ full compaction" <br>
<br>
Especially since tolerating allowed input values and mapping
them to specific non-exiting behaviours allows us to modify
production JVM's on the fly<br>
without causing loss of availability. (Consider a future in
which this option becomes a "manageable"; you would then be
faced with the same<br>
question, and it seems as though making this choice now would
help maintain consistency and robustness going forward -- we
could of course<br>
always throw a "illegal value exception" or such at that
point, but allowing the specification of "never _force_ full
compaction" (unless the JVM<br>
otherwise chooses to) would appear to be a choice to allow
users; mapping negative and 0 values to that setting would
avoid having to<br>
throw an error.) However, I understand that this is somewhat
subjective, so I am willing to go with whatever the majority
consensus here<br>
mght be. It just seemed more pleasant to:<br>
(1) allow the specification of reasonable behaviour (i.e.
never _force_ ...)<br>
(2) map the full domain of the option to a reasonable
behaviour (i.e. allow <= 0 to map to never _force_ ..)<br>
<br>
Comments?<br>
</div>
</div>
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<br>
I see your point, and I think this should be fairly straight forward
to fix. However it will require some more testing etc. I can do
that, but I don't think I know enough to say whether or not the
extra work is worth it. How important is this option? Is it
something that customers use a lot?<br>
<br>
Thanks,<br>
Bengt<br>
<br>
<blockquote
cite="mid:CABzyjym+XcbDArUOPdpqev=a-vdTy5gzqJUtnfPHyPfK9AN+=A@mail.gmail.com"
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<div class="gmail_quote">
<div><br>
-- ramki<br>
<br>
<br>
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<blockquote class="gmail_quote" style="margin: 0pt 0pt 0pt
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<br>
CR:<br>
<br>
7110718 -XX:MarkSweepAlwaysCompactCount=0 crashes the JVM<br>
<a moz-do-not-send="true"
href="http://bugs.sun.com/bugdatabase/view_bug.do?bug_id=7110718"
target="_blank">http://bugs.sun.com/bugdatabase/view_bug.do?bug_id=7110718</a><br>
<br>
Thanks,<br>
<font color="#888888">
Bengt<br>
</font></blockquote>
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