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Hi Poonam,<br>
<br>
Thanks for looking at this!<br>
<br>
<br>
<div class="moz-cite-prefix">On 2015-10-26 21:22, Poonam Bajaj
Parhar wrote:<br>
</div>
<blockquote cite="mid:562E8B8C.10305@oracle.com" type="cite">
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Hello Bengt,<br>
<br>
I am going to try out the new logging myself but some quick
feedback from the examples output you had provided:<br>
<br>
<b>-Xlog:gc:</b><br>
<br>
1. It is great to have the start and end timestamps included on
the same GC log line.<br>
</blockquote>
<br>
Great! :)<br>
<br>
<blockquote cite="mid:562E8B8C.10305@oracle.com" type="cite"> <br>
2.<br>
<pre><i>[0.643s][info ][gc] GC#5 GC young (G1 Evacuation Pause) end 91M->61M(128M) (0.632s, 0.643s) 11.399ms</i><i>
</i><i>[1.499s][info ][gc] GC#16 GC remark end 73M->73M(128M) (1.486s, 1.499s) 12.545ms
[1.500s][info ][gc] GC#16 GC cleanup end 73M->73M(128M) (1.499s, 1.500s) 0.729ms</i>
</pre>
<br>
It does not make much of a sense here to include 'end' in the log
lines. If there is no line with a 'start' then I think it does not
serve any purpose to have 'end' for these GC lines.<br>
</blockquote>
<br>
I see your point. However, when the start logging is included I
think it makes sense to have some marker on this line saying that it
is the end logging. I would prefer that the line looks exactly the
same in both cases. But I am very open to suggestions for another
way to format the line. I agree that it looks odd with "end" when
there is no start. On the other hand the logging is done at the end
of the GC, which could be relevant to include in the information.
I've been thinking about "done" instead. Or "completed". Any other
suggestions?<br>
<br>
<blockquote cite="mid:562E8B8C.10305@oracle.com" type="cite"> <br>
3. There are some white-spaces after the 'level' ([info ]), it'd
be good if those can be removed.<br>
</blockquote>
<br>
This is from the logging framework and not part of the GC log
implementation. I think you need to bring this up on the
serviceability list.<br>
<br>
<br>
<blockquote cite="mid:562E8B8C.10305@oracle.com" type="cite"> <br>
<b>-Xlog:gc*</b><b>:</b><br>
<br>
1. Is there a specific reason to print the tag (gc) and other
sub-tags in different order? For example, we have 'start, gc', and
the order is different in 'gc, heap'.<br>
<i><a moz-do-not-send="true">
<pre>[1.300s][info ][start,gc ] GC#3 GC (Allocation Failure) DefNew start
[1.300s][info ][start,gc ] GC#4 Full GC (Allocation Failure) start
[2.154s][info ][gc ] GC#4 Full GC (Allocation Failure) end 93M->59M(123M) (1.300s, 2.154s) 854.130ms
[2.154s][info ][gc,heap ] GC#3 def new generation: 36767K->0K(39296K)
[2.154s][info ][gc,heap ] GC#3 tenured generation: 58893K->61204K(87424K)
[2.154s][info ][gc,metaspace] GC#3 Metaspace: 2953K->2953K(1056768K)</pre>
</a></i>if possible, I think we should have the order 'main-tag,
sub-tag' at all the places.<br>
</blockquote>
<br>
Very well spotted! There is a technical reason for this. I have been
trying to work around it but for now the simplest solution was to
have the start tag first.<br>
<br>
The technical reason is that the "start" tag is added to any other
tags for the timing class that is used to track the time for a GC
(or a GC sub event). Currently the only way to add an extra tag is
to do it at the beginning of the tag set.<br>
<br>
I can try to work around this, or try to get the unified logging
framework to let me append a tag instead. But if it is ok I'd like
to leave it like this for now and file an RFE to fix this later.<br>
<br>
Thanks,<br>
Bengt<br>
<br>
<blockquote cite="mid:562E8B8C.10305@oracle.com" type="cite"> <br>
Thanks,<br>
Poonam<br>
<br>
<div class="moz-cite-prefix">On 10/26/2015 5:26 AM, Bengt Rutisson
wrote:<br>
</div>
<blockquote cite="mid:562E1BE5.7090604@oracle.com" type="cite"> <br>
Hi again everyone, <br>
<br>
An update on the work for JEP 271 Unified GC Logging. <br>
<br>
I now have a working prototype that covers all GCs. Here are
some examples comparing the old format (using -XX:+PrintGC and
-XX:+PrintGCDetails) with the new format (using -Xlog): <br>
<br>
<a moz-do-not-send="true" class="moz-txt-link-freetext"
href="http://cr.openjdk.java.net/%7Ebrutisso/JEP-271/pre-review.00/compare.html">http://cr.openjdk.java.net/~brutisso/JEP-271/pre-review.00/compare.html</a>
<br>
<br>
The new logging format, using -Xlog, is much more flexible than
the old format. So, the comparison table on the above page is by
no means complete. I hope it will give a good overview, but to
get a real feel for how the new logging works I think it is
necessary to run locally and play around with the logging
options. <br>
<br>
Here is a webrev of the changes so far: <br>
<a moz-do-not-send="true" class="moz-txt-link-freetext"
href="http://cr.openjdk.java.net/%7Ebrutisso/JEP-271/pre-review.00/webrev.00/">http://cr.openjdk.java.net/~brutisso/JEP-271/pre-review.00/webrev.00/</a>
<br>
<br>
There is still work to do and I have some known issues with the
code changes. So, I am currently not asking for too much
feedback on the actual code changes. I am more looking for
feedback on the logging behavior. The webrev can be useful to
get a feel for what the code changes will look like but mostly I
think it can be used to apply the patch and build your own
HotSpot to try out the new logging. <br>
<br>
Some changes based on the initial feedback: <br>
- Start and end timestamps for the GC included on the GC log
line. <br>
- Printing the unit of a value without a space. I.e. "10.345ms"
instead of "10.345 ms". (Still working on fixing this in all
places as well as trying to use milliseconds instead of seconds
in as many places as possible.) <br>
- Printing heap change information with a fixed unit. I am now
using M for overall heap transition and K for detailed
information on the debug level. <br>
- Removed the "summary" tag. Instead the end logging for a GC
includes all relevant information. <br>
<br>
All feedback is very welcome! <br>
<br>
Thanks, <br>
Bengt <br>
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