Request for review (S): 7166894 Add gc cause to Full GC logging for all collectors
bengt.rutisson at oracle.com
Fri May 11 11:30:16 UTC 2012
Thanks again for looking at this.
I had to make some minor changes make it compile on all platforms.
Mostly some explicit casts to const char*. Here is an updated webrev:
More comments inline.
On 2012-05-08 16:43, Krystal Mok wrote:
> Hi Bengt,
> The current factoring looks nice and uniform. Thanks :-)
> But for most minor GCs and both CMS pause phases, the extra logging
> doesn't really give additional information.
> Most minor GCs are going to say "Allocation Failure", and the two CMS
> phases would change from, e.g.
> [GC [1 CMS-initial-mark
> to something like
> [GC (CMS Initial Mark) [1 CMS-initial-mark
> which is probably reasonable given the scope of the change, but not
> really helpful.
> The "real cause", such as which generation (or perhaps System.gc()
> with ExplicitGCInvokesConcurrent, or even GC locker) is triggering
> this collection cycle, may be more useful, but it's hard to fit into
> the current form.
Yes, I think you are correct in both cases. The gc cause that we have
available does not always add a lot of information. This is relevant to
fix but it is a slightly different issue than what this patch sets out
to fix. Let's try to get this in first and then evaluate how the GC
causes should be set.
> - Kris
> On Tue, May 8, 2012 at 10:18 PM, Bengt Rutisson
> <bengt.rutisson at oracle.com <mailto:bengt.rutisson at oracle.com>> wrote:
> Hi again everyone,
> It seems like the feedback on hotspot-gc-use is that we should add
> the GC cause to all collectors but also provide a switch to turn
> this logging off.
> Here is an updated webrev:
> * GC cause logged for all collectors
> * Added the flag -XX:-PrintGCCause to turn the new information off
> * Refactored the string concatenation code into a helper class
> I guess I will also have to update the CR to now reflect the fact
> that this does not just concern full GCs anymore.
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