RFR: 8204210: Implementation: JEP 333: ZGC: A Scalable Low-Latency Garbage Collector (Experimental)

[Per Liden]

Thanks for reviewing those, Coleen!

/Per

On 2018-06-05 15:46, coleen.phillimore at oracle.com wrote:
> 
> Ok, I stand corrected.  The few runtime changes look fine to me.
> Coleen
> 
> On 6/5/18 9:44 AM, coleen.phillimore at oracle.com wrote:
>>
>> Hi, I was going to review the runtime pieces of this change but there 
>> are none!  Nicely factored and thank you for upstreaming the runtime 
>> changes to support this already.
>>
>> Coleen
>>
>> On 6/1/18 5:41 PM, Per Liden wrote:
>>> Hi,
>>>
>>> Please review the implementation of JEP 333: ZGC: A Scalable 
>>> Low-Latency Garbage Collector (Experimental)
>>>
>>> Please see the JEP for more information about the project. The JEP is 
>>> currently in state "Proposed to Target" for JDK 11.
>>>
>>> https://bugs.openjdk.java.net/browse/JDK-8197831
>>>
>>> Additional information in can also be found on the ZGC project wiki.
>>>
>>> https://wiki.openjdk.java.net/display/zgc/Main
>>>
>>>
>>> Webrevs
>>> -------
>>>
>>> To make this easier to review, we've divided the change into two 
>>> webrevs.
>>>
>>> * ZGC Master: http://cr.openjdk.java.net/~pliden/8204210/webrev.0-master
>>>
>>>   This patch contains the actual ZGC implementation, the new unit 
>>> tests and other changes needed in HotSpot.
>>>
>>> * ZGC Testing: 
>>> http://cr.openjdk.java.net/~pliden/8204210/webrev.0-testing
>>>
>>>   This patch contains changes to existing tests needed by ZGC.
>>>
>>>
>>> Overview of Changes
>>> -------------------
>>>
>>> Below follows a list of the files we add/modify in the master patch, 
>>> with a short summary describing each group.
>>>
>>> * Build support - Making ZGC an optional feature.
>>>
>>>   make/autoconf/hotspot.m4
>>>   make/hotspot/lib/JvmFeatures.gmk
>>>   src/hotspot/share/utilities/macros.hpp
>>>
>>> * C2 AD file - Additions needed to generate ZGC load barriers (adlc 
>>> does not currently offer a way to easily break this out).
>>>
>>>   src/hotspot/cpu/x86/x86.ad
>>>   src/hotspot/cpu/x86/x86_64.ad
>>>
>>> * C2 - Things that can't be easily abstracted out into ZGC specific 
>>> code, most of which is guarded behind a #if INCLUDE_ZGC and/or if 
>>> (UseZGC) condition. There should only be two logic changes (one in 
>>> idealKit.cpp and one in node.cpp) that are still active when ZGC is 
>>> disabled. We believe these are low risk changes and should not 
>>> introduce any real change i behavior when using other GCs.
>>>
>>>   src/hotspot/share/adlc/formssel.cpp
>>>   src/hotspot/share/opto/*
>>>   src/hotspot/share/compiler/compilerDirectives.hpp
>>>
>>> * General GC+Runtime - Registering ZGC as a collector.
>>>
>>>   src/hotspot/share/gc/shared/*
>>>   src/hotspot/share/runtime/vmStructs.cpp
>>>   src/hotspot/share/runtime/vm_operations.hpp
>>>   src/hotspot/share/prims/whitebox.cpp
>>>
>>> * GC thread local data - Increasing the size of data area by 32 bytes.
>>>
>>>   src/hotspot/share/gc/shared/gcThreadLocalData.hpp
>>>
>>> * ZGC - The collector itself.
>>>
>>>   src/hotspot/share/gc/z/*
>>>   src/hotspot/cpu/x86/gc/z/*
>>>   src/hotspot/os_cpu/linux_x86/gc/z/*
>>>   test/hotspot/gtest/gc/z/*
>>>
>>> * JFR - Adding new event types.
>>>
>>>   src/hotspot/share/jfr/*
>>>   src/jdk.jfr/share/conf/jfr/*
>>>
>>> * Logging - Adding new log tags.
>>>
>>>   src/hotspot/share/logging/*
>>>
>>> * Metaspace - Adding a friend declaration.
>>>
>>>   src/hotspot/share/memory/metaspace.hpp
>>>
>>> * InstanceRefKlass - Adjustments for concurrent reference processing.
>>>
>>>   src/hotspot/share/oops/instanceRefKlass.inline.hpp
>>>
>>> * vmSymbol - Disabled clone intrinsic for ZGC.
>>>
>>>   src/hotspot/share/classfile/vmSymbols.cpp
>>>
>>> * Oop Verification - In four cases we disabled oop verification 
>>> because it do not makes sense or is not applicable to a GC using load 
>>> barriers.
>>>
>>>   src/hotspot/cpu/x86/c1_LIRAssembler_x86.cpp
>>>   src/hotspot/cpu/x86/stubGenerator_x86_64.cpp
>>>   src/hotspot/share/compiler/oopMap.cpp
>>>   src/hotspot/share/runtime/jniHandles.cpp
>>>
>>> * StackValue - Apply a load barrier in case of OSR. This is a bit of 
>>> a hack. However, this will go away in the future, when we have the 
>>> next iteration of C2's load barriers in place (aka "C2 late barrier 
>>> insertion").
>>>
>>>   src/hotspot/share/runtime/stackValue.cpp
>>>
>>> * JVMTI - Adding an assert() to catch problems if the tagmap hashing 
>>> is changed in the future.
>>>
>>>   src/hotspot/share/prims/jvmtiTagMap.cpp
>>>
>>> * Legal - Adding copyright/license for 3rd party hash function used 
>>> in ZHash.
>>>
>>>   src/java.base/share/legal/c-libutl.md
>>>
>>> * SA - Adding basic ZGC support.
>>>
>>>   src/jdk.hotspot.agent/share/classes/sun/jvm/hotspot/*
>>>
>>>
>>> Testing
>>> -------
>>>
>>> * Unit testing
>>>
>>>   A number of new ZGC specific gtests have been added, in 
>>> test/hotspot/gtest/gc/z/
>>>
>>> * Regression testing
>>>
>>>   No new failures in Mach5, with ZGC enabled, tier{1,2,3,4,5,6}
>>>   No new failures in Mach5, with ZGC disabled, tier{1,2,3}
>>>
>>> * Stress testing
>>>
>>>   We have been continuously been running a number stress tests 
>>> throughout the development, these include:
>>>
>>>     specjbb2000
>>>     specjbb2005
>>>     specjbb2015
>>>     specjvm98
>>>     specjvm2008
>>>     dacapo2009
>>>     test/hotspot/jtreg/gc/stress/gcold
>>>     test/hotspot/jtreg/gc/stress/systemgc
>>>     test/hotspot/jtreg/gc/stress/gclocker
>>>     test/hotspot/jtreg/gc/stress/gcbasher
>>>     test/hotspot/jtreg/gc/stress/finalizer
>>>     Kitchensink
>>>
>>>
>>> Thanks!
>>>
>>> /Per, Stefan & the ZGC team
>>
>