RFR (XS): 8200362: G1Mux2Closure should disable implicit oop verification (original) (raw)

Stefan Johansson stefan.johansson at oracle.com
Thu Mar 29 09:25:01 UTC 2018

On 2018-03-29 11:20, Stefan Karlsson wrote:

On 2018-03-29 11:02, Thomas Schatzl wrote: Hi Stefan,

On Thu, 2018-03-29 at 09:52 +0200, Stefan Johansson wrote: Hi Thomas,

On 2018-03-28 17:27, Thomas Schatzl wrote: Hi all,

can I have reviews for this small change that fixes some annoyance when debugging with G1? In particular, G1Mux2Closure is used by verification to verify and in case of error print out g1 specific error messages. However, since G1Mux2Closure is an OopClosure, it is actually wrapped by NoHeaderExtendedOopClosure in oopiterate* calls. ExtendedOopClosure has its own verification that is very generic, and may trigger in the same situations as G1Mux2Closure. Disable this implicit verification for G1Mux2Closure so that we always get the g1 specific error messages. CR: https://bugs.openjdk.java.net/browse/JDK-8200362 Webrev: http://cr.openjdk.java.net/~tschatzl/8200362/webrev/ Nice change, always good to get detailed information. I think you need to change the code using the G1Mux2Closure as well. On line 666 in heapRegion.cpp: G1Mux2Closure mux(&vlcl, &vrcl); obj->oopiteratenoheader(&mux); This should now be a normal oopiterate(&mux) to make sure the right verification is done. Fixed. Also looked through other closures used for verification. http://cr.openjdk.java.net/~tschatzl/8200362/webrev.0to1 (diff) http://cr.openjdk.java.net/~tschatzl/8200362/webrev.1 (full) Looks good. I like that we get rid of usages of oopiteratenoheader. Maybe we should remove the other usages in G1, as a separate RFE. I like the sound of that, maybe something for Leo to look at. Any history or reason why we have these?

StefanJ

StefanK

Thomas

More information about the hotspot-gc-dev mailing list