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Hi Kris,<br>
<br>
Thanks for looking at this!<br>
<br>
Good point regarding CMS. I guess I am a bit concerned about
changing that since it might start breaking more parsers. I'll send
a question out on the hotspot-gc-use mailing list to get some
feedback.<br>
<br>
If we do go for adding this information to CMS we can probably also
take the chance of adding it to all the young GCs.<br>
<br>
I looked at the log sample you referred to. It looks like you were
logging more details about exactly why a GC was triggered. That is
probably a good idea, but for now I think we should settle for just
the text message describing the cause.<br>
<br>
Thanks again for looking at this,<br>
Bengt<br>
<br>
On 2012-05-07 15:19, Krystal Mok wrote:
<blockquote
cite="mid:CA+cQ+tSFTG9P62aCSBQWucom3Cg6SYDgJQ1HJO=4yJsX6ZJwqA@mail.gmail.com"
type="cite">Hi Bengt,
<div><br>
</div>
<div>FYI, I did something similar to CMS as well, covered by a new
flag called "PrintGCReason" in my build.</div>
<div>It's primitive, compared with your change. I was striving to
keep the log within the brackets just as they were, and instead
print extra information before the opening bracket, on a
separate line. The parsing tool we use tend to ignore the lines
it couldn't recognize, so doing it this way interrupted the tool
the least.</div>
<div><br>
</div>
<div>An example of the output can be found here [1], page 42. The
motivation to add the extra logging was to track down a
mysterious behavior in CMS that it keep doing back-to-back
collections, without much gains, as explained in [1]. I needed
to know why it was triggered. Some of our applications actually
liked the extra logging, so it remained in the code base after
the bug was found.</div>
<div><br>
</div>
<div>Anyway, I like the idea of getting more info out of GC logs,
in a uniform way.</div>
<div>Would you mind adding the extra logging to CMS, too?</div>
<div><br>
</div>
<div>- Kris</div>
<div><br>
</div>
<div>[1]: <a moz-do-not-send="true"
href="http://www.slideshare.net/RednaxelaFX/jvm-taobao">http://www.slideshare.net/RednaxelaFX/jvm-taobao</a><br>
<br>
<div class="gmail_quote">On Mon, May 7, 2012 at 8:31 PM, Bengt
Rutisson <span dir="ltr"><<a moz-do-not-send="true"
href="mailto:bengt.rutisson@oracle.com" target="_blank">bengt.rutisson@oracle.com</a>></span>
wrote:<br>
<blockquote class="gmail_quote" style="margin:0 0 0
.8ex;border-left:1px #ccc solid;padding-left:1ex">
<br>
Hi all,<br>
<br>
Can I get a couple of reviews of this simple change:<br>
<a moz-do-not-send="true"
href="http://cr.openjdk.java.net/%7Ebrutisso/7166894/webrev/"
target="_blank">http://cr.openjdk.java.net/~brutisso/7166894/webrev/</a><br>
<br>
Background:<br>
I recently pushed a similar fix for G1 as "7163848: G1: Log
GC Cause for a GC". That fix adds the GC cause information
to all G1 GCs. It was discussed if we should do this for all
collectors and we came to the conclusion that it would be
fairly safe to do it for all Full GCs. These log messages
already contain the text "(System)" or "(System.gc())" when
a System.gc() happens and PrintGCDetails are enabled. Now
they will always contain the cause in parenthesis, even when
only PrintGC is enabled. Hopefully most parsing will work
with this.<br>
<br>
Thanks,<br>
Bengt<br>
</blockquote>
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