Summary: Add a list of nmethods to the RSet for a region that contain references into the region. Skip scanning the code cache during root scanning and scan the nmethod lists during RSet scanning instead.
Reviewed-by: tschatzl, brutisso, mgerdin, twisti, kvn

Reviewed-by: acorn, coleenp, sla
Contributed-by: NKaren Kinnear &lt;karen.kinnear@oracle.com&gt;, Bengt Rutisson &lt;bengt.rutisson@oracle.com&gt;, Calvin Cheung &lt;calvin.cheung@oracle.com&gt;, Erik Gahlin &lt;erik.gahlin@oracle.com&gt;, Erik Helin &lt;erik.helin@oracle.com&gt;, Jesper Wilhelmsson &lt;jesper.wilhelmsson@oracle.com&gt;, Keith McGuigan &lt;keith.mcguigan@oracle.com&gt;, Mattias Tobiasson &lt;mattias.tobiasson@oracle.com&gt;, Markus Gronlund &lt;markus.gronlund@oracle.com&gt;, Mikael Auno &lt;mikael.auno@oracle.com&gt;, Nils Eliasson &lt;nils.eliasson@oracle.com&gt;, Nils Loodin &lt;nils.loodin@oracle.com&gt;, Rickard Backman &lt;rickard.backman@oracle.com&gt;, Staffan Larsen &lt;staffan.larsen@oracle.com&gt;, Stefan Karlsson &lt;stefan.karlsson@oracle.com&gt;, Yekaterina Kantserova <yekaterina.kantserova@oracle.com>

Summary: Improve the output of G1PrintRegionLivenessInfo by adding a per-region remembered set size information column
Reviewed-by: jwilhelm, johnc

Reviewed-by: johnc, brutisso

Reviewed-by: brutisso, jmasa

Summary: If the marking stack overflows while the marking tasks are draining the SATB buffers, remark will exit with some SATB buffers left unprocessed. Relax the guarantee to allow for overflow.
Reviewed-by: jmasa, brutisso

Summary: Skip reference processing if the global marking stack overflows during remark. Refactor and rename set_phase(); move code that sets the concurrency level into its own routine. Do not call set_phase() from within parallel reference processing; use the concurrency level routine instead. The marking state should only set reset by CMTask[0] during the concurrent phase of the marking cycle; if an overflow occurs at any stage during the remark, the marking state will be reset after reference processing.
Reviewed-by: brutisso, jmasa

Summary: In CMTask::do_marking_step(), Skip offering termination and entering the first and second synchronization barriers if called from a serial context, i.e. the VM thread.
Reviewed-by: brutisso, tschatzl

Summary: ASSERT and other symbols used incorrectly with #if are supposed to be defined or not.
Reviewed-by: dholmes, mikael

Summary: Update the task local finger to the start of the next object when marking aborts, in order to avoid the redundant scanning of all 0's when the marking task restarts, if otherwise updating to the next word. In addition, reuse the routine nextObject() in routine iterate().
Reviewed-by: johnc, ysr
Contributed-by: Ntamao <tao.mao@oracle.com>

Summary: Reuse the parallel reference processing oop closures during serial reference processing.
Reviewed-by: brutisso

Summary: Set ConcGCThreads to the calculated number of marking threads.
Reviewed-by: jmasa, ysr

Summary: Check that the concurrent marking worker gang exists in ConcurrentMark::print_worker_threads_on(). Changes were also reviewed by Vitaly Davidovich <vitalyd@gmail.com>.
Reviewed-by: brutisso

8007772: G1: assert(!hr->isHumongous() || mr.start() == hr->bottom()) failed: the start of HeapRegion and MemRegion should be consistent for humongous regions
Summary: In do_marking_step(), we should always give up current region after scanning the object, if the region is humongous.
Reviewed-by: brutisso, jwilhelm, tamao

Summary: Skip unnecessary scanning of bitmap for unmarked humongous objects/regions.
Reviewed-by: jwilhelm, johnc
Contributed-by: NTao Mao <tao.mao@oracle.com>

Summary: Reset the marking state, including the mark stack overflow flag, in the event of a marking stack overflow during serial reference processing.
Reviewed-by: jmasa

Summary: Restore non-silent output of heap verification.
Reviewed-by: ysr, brutisso, jmasa

Summary: Change the type of various task num fields, parameters etc to unsigned and rename them to be more consistent with the other collectors. Code changes were also reviewed by Vitaly Davidovich.
Reviewed-by: johnc
Contributed-by: NKaushik Srenevasan <kaushik@twitter.com>

Summary: Set the value of MarkStackSize to a value based on the number of parallel marking threads with a reasonable minimum. Expand the marking stack if we have to restart marking due to an overflow up to a reasonable maximum. Allocate the underlying space for the marking stack from virtual memory.
Reviewed-by: jmasa, brutisso

Summary: The clipping code in the routine that sets the bits for a range of cards, in the liveness accounting verification code was incorrect. It set all the bits in the card bitmap from the given starting index which would lead to spurious marking verification failures.
Reviewed-by: brutisso, jwilhelm, jmasa

Reviewed-by: brutisso, johnc, ysr
Contributed-by: NHal Mo <kungu.mjh@taobao.com>

Summary: Remove PermGen, allocate meta-data in metaspace linked to class loaders, rewrite GC walking, rewrite and rename metadata to be C++ classes
Reviewed-by: jmasa, stefank, never, coleenp, kvn, brutisso, mgerdin, dholmes, jrose, twisti, roland
Contributed-by: Njmasa &lt;jon.masamitsu@oracle.com&gt;, stefank &lt;stefan.karlsson@oracle.com&gt;, mgerdin &lt;mikael.gerdin@oracle.com&gt;, never <tom.rodriguez@oracle.com>

Summary: Various cleanups as a prelude to introducing iterators for HeapRegions.
Reviewed-by: johnc, brutisso

Summary: Also reviewed by: vitalyd@gmail.com. Move the timing out of G1CollectorPolicy into the G1GCPhaseTimes class
Reviewed-by: johnc

7151532: DCmd for hotspot native memory tracking
Summary: Implementation of native memory tracking phase 1, which tracks VM native memory usage, and related DCmd
Reviewed-by: acorn, coleenp, fparain

Summary: Removed the HeapRegion::_top_at_conc_mark_count field. It is no longer needed as a result of the changes for 6888336 and 7127706. Refactored the closures that finalize and verify the liveness counting data so that common functionality was placed into a base class.
Reviewed-by: brutisso, tonyp

Summary: Cleanup of the CSet chooser class: standardize on uints for region num and indexes (instead of int, jint, etc.), make the method / field naming style more consistent, remove a lot of dead code.
Reviewed-by: johnc, brutisso

Summary: Change the type of fields / variables / etc. that represent region counts and indeces from size_t to uint.
Reviewed-by: iveresov, brutisso, jmasa, jwilhelm

Summary: removed oop_verify_old_oop and allow_dirty. Also reviewed by: alexlamsl@gmail.com
Reviewed-by: jmasa, jwilhelm

Summary: Added log levels "fine", "finer" and "finest". Let PrintGC map to "fine" and PrintGCDetails map to "finer". Separated out the per worker information in the G1 logging to the "finest" level.
Reviewed-by: stefank, jwilhelm, tonyp, johnc

Summary: Removed lots of dead code after some recent conc mark changes.
Reviewed-by: brutisso, johnc

Summary: Re-enable survivors during the initial-mark pause. Afterwards, the concurrent marking threads have to scan them and mark everything reachable from them. The next GC will have to wait for the survivors to be scanned.
Reviewed-by: brutisso, johnc

Summary: Remove the separate counting phase of concurrent marking by tracking the amount of marked bytes and the cards spanned by marked objects in marking task/worker thread local data structures, which are updated as individual objects are marked.
Reviewed-by: brutisso, tonyp

Summary: Extend the jmap -heap output for G1 to include some more G1-specific information.
Reviewed-by: brutisso, johnc, poonam

Summary: Removed references to CMS in the concurrentMark.cpp/hpp files.
Reviewed-by: tonyp, jmasa, johnc

Summary: There is a high number of mispredicted branches associated with calling BitMap::iteratate() from within CMBitMapRO::iterate(). Implement a version of CMBitMapRO::iterate() directly using inline-able routines.
Reviewed-by: tonyp, iveresov

Summary: This change simplifies the interaction between GC and concurrent marking. By disabling survivor spaces during the initial-mark pause we don't need to propagate marks of objects we copy during each GC (since we never need to copy an explicitly marked object).
Reviewed-by: johnc, brutisso

Summary: Replaced the code with a ShouldNotReachHere
Reviewed-by: tonyp, jmasa

Summary: Parallelize the removal of self forwarding pointers etc. by wrapping in a HeapRegion closure, which is then wrapped inside an AbstractGangTask.
Reviewed-by: tonyp, iveresov

Summary: Running G1 with ParallelGCThreads==0 results in various crashes and asserts. Most of these are caused by unguarded references to the worker threads array or an incorrect number of active workers.
Reviewed-by: jmasa, tonyp