RFR (XS) 8209802: JFR failed to build when certain garbage collectors are disabled
thomas.schatzl at oracle.com
Tue Oct 23 11:43:17 UTC 2018
On Fri, 2018-10-19 at 15:04 -0700, Derek Thomson wrote:
> Hi all,
> I saw this bug and thought I could take a stab at it. I tweaked the
> #ifs to make it work for -g1gc, then decided to keep going and make
> sure all valid GC exclusions work.
> It's worth noting that you can't say '-serialgc' without also using
> '-cmsgc', as CMS relies on serial.
> Could someone review it please?
> Webrev: http://cr.openjdk.java.net/~jcbeyler/8209802/webrev.00/
> Bug: https://bugs.openjdk.java.net/browse/JDK-8209802
- wouldn't it be more useful to tweak the makefiles so that setting
-serialgc implies -cmsgc, and conversely, +cmsgc implies +serialgc?
Or, for me as fine, if conflicting options are set, return with an
Because it looks like with this change, with -serialgc +cmsgc you will
get a non-functioning CMS anyway. I.e. generate a nonsensical
This removes a lot of #ifdef SERIALGC I think.
I am actually not sure it is actually possible to compile (and
succesfully run any of the "old" gcs) without serial gc at the moment.
- the friend declaration in heapRegion.hpp can be removed instead of
ifdef'ed. G1 does not use these methods. HeapRegion is still a
CompactibleSpace/Space, but it actually should not any more.
(And applying the Serial gc full gc to G1 will crash the VM)
Anyway, for this change, just remove the friend declaration completely.
- in jfr.cpp, I would prefer the ifdef's completely removed the
TRACE_REQUEST_FUNC(G1HeapRegionInformation), if possible. Otherwise, I
think it is better to remove starting from the body of this method.
- in jfrType.cpp the question is if compiling without g1 could remove
the entire declaration of G1HeapRegionTypeConstant.
Cc'ing hotspot-jfr-dev at openjdk.java.net as the jfr devs might have an
idea how to accomplish that.
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