Summary: G1 now uses two reference processors - one is used by concurrent marking and the other is used by STW GCs (both full and incremental evacuation pauses). In an evacuation pause, the reference processor is embedded into the closures used to scan objects. Doing so causes causes reference objects to be 'discovered' by the reference processor. At the end of the evacuation pause, these discovered reference objects are processed - preserving (and copying) referent objects (and their reachable graphs) as appropriate.
Reviewed-by: ysr, jwilhelm, brutisso, stefank, tonyp

Summary: If and when the reference handler thread is able to use the discovered field to link reference objects in its pending list, so will GC. In that case, GC will scan through this field once a reference object has been placed on the pending list, but not scan that field before that stage, as the field is used by the concurrent GC thread to link discovered objects. When ReferenceHandleR thread does not use the discovered field for the purpose of linking the elements in the pending list, as would be the case in older JDKs, the JVM will fall back to the old behaviour of using the next field for that purpose.
Reviewed-by: jcoomes, mchung, stefank

Summary: Remove the sentinelRef and let the last Reference in a discovered chain point back to itself.
Reviewed-by: ysr, jmasa

Summary: Use _max_num_q = max(discovery_degree, processing_degree), and let balance_queues() redistribute from discovery_degree to processing_degree of queues. This should also allow a more dynamic and flexible parallelism policy in the future.
Reviewed-by: jmasa, johnc

Summary: Relaxed the assert by allowing NULL referents when discovery may be concurrent.
Reviewed-by: johnc, jcoomes

Summary: Enable reference discovery during concurrent marking by setting the reference processor field of the concurrent marking closure. Keep reference objects on the discovered reference lists alive during incremental evacuation pauses until they are processed at the end of concurrent marking.
Reviewed-by: ysr, tonyp

Summary: Replaced MakeDeps and the includeDB files with more standardized solutions.
Reviewed-by: coleenp, kvn, kamg

Summary: Associate number of GC workers with the workgang as opposed to the task.
Reviewed-by: johnc, ysr

Summary: Change all the Sun copyrights to Oracle copyright
Reviewed-by: ohair

Summary: Adjust assertion checking for ExplicitGCInvokesConcurrentAndUnloadsClasses as a reason for class unloading
Reviewed-by: ysr

Reviewed-by: kvn, twisti

Summary: Source changes for older compilers plus makefile changes.
Reviewed-by: xlu

Summary: Override should_remember_klasses() and remember_klass() as needed.
Reviewed-by: ysr, jcoomes

Summary: Modifications to G1 so as to allow the use of compressed oops.
Reviewed-by: apetrusenko, coleenp, jmasa, kvn, never, phh, tonyp

Summary: Update copyright for files that have been modified in 2009, up to 03/09
Reviewed-by: katleman, tbell, ohair

Summary: Avoid overflow list walk in CMS & ParNew when it is unnecessary. Fix a couple of correctness issues, including a C-heap leak, in ParNew at the intersection of promotion failure, work queue overflow and object array chunking. Add stress testing option and related assertion checking.
Reviewed-by: jmasa

Summary: Renamed Reference{Policy,Pocessor} methods from snap{,_policy}() to setup{,_policy}()
Reviewed-by: apetrusenko

Summary: For current soft-ref clearing policies, we can decide at marking time if a soft-reference will definitely not be cleared, postponing the decision of whether it will definitely be cleared to the final reference processing phase. This can be especially beneficial in the case of concurrent collectors where the marking is usually concurrent but reference processing is usually not.
Reviewed-by: jmasa

Summary: When we encounter marking stack overflow during precleaning of Reference lists, we were using the overflow list mechanism, which can cause problems on account of mutating the mark word of the header because of conflicts with mutator accesses and updates of that field. Instead we should use the usual mechanism for overflow handling in concurrent phases, namely dirtying of the card on which the overflowed object lies. Since precleaning effectively does a form of discovered list processing, albeit with discovery enabled, we needed to adjust some code to be correct in the face of interleaved processing and discovery.
Reviewed-by: apetrusenko, jcoomes

Summary: Update copyright year for files that have been modified in 2008
Reviewed-by: ohair, tbell

Summary: First mercurial integration of the code for the Garbage-First garbage collector.
Reviewed-by: apetrusenko, iveresov, jmasa, sgoldman, tonyp, ysr

Summary: Compressed oops in instances, arrays, and headers. Code contributors are coleenp, phh, never, swamyv
Reviewed-by: jmasa, kamg, acorn, tbell, kvn, rasbold

Summary: Disable parallel reference processing when there are no worker threads
Reviewed-by: apetrusenko, pbk, jmasa, tonyp