7039089: G1: changeset for 7037276 broke heap verification, and related cleanups

In G1 heap verification, we no longer scan perm to G1-collected heap refs as part of process_strong_roots() but rather in a separate explicit oop iteration over the perm gen. This preserves the original perm card-marks. Added a new assertion in younger_refs_iterate() to catch a simple subcase where the user may have forgotten a prior save_marks() call, as happened in the case of G1's attempt to iterate perm to G1 refs when verifying the heap before exit. The assert was deliberately weakened for ParNew+CMS and will be fixed for that combination in a future CR. Also made some (non-G1) cleanups related to code and comments obsoleted by the migration of Symbols to the native heap.

Reviewed-by: iveresov, jmasa, tonyp
This commit is contained in:
Y. Srinivas Ramakrishna 2011-04-26 21:17:24 -07:00
parent e3121a5a43
commit d86311b13c
8 changed files with 69 additions and 28 deletions

View file

@ -192,9 +192,8 @@ public:
SO_None = 0x0,
SO_AllClasses = 0x1,
SO_SystemClasses = 0x2,
SO_Symbols = 0x4,
SO_Strings = 0x8,
SO_CodeCache = 0x10
SO_Strings = 0x4,
SO_CodeCache = 0x8
};
FlexibleWorkGang* workers() const { return _workers; }
@ -208,14 +207,13 @@ public:
// Invoke the "do_oop" method the closure "roots" on all root locations.
// If "collecting_perm_gen" is false, then roots that may only contain
// references to permGen objects are not scanned. If true, the
// "perm_gen" closure is applied to all older-to-younger refs in the
// references to permGen objects are not scanned; instead, in that case,
// the "perm_blk" closure is applied to all outgoing refs in the
// permanent generation. The "so" argument determines which of roots
// the closure is applied to:
// "SO_None" does none;
// "SO_AllClasses" applies the closure to all entries in the SystemDictionary;
// "SO_SystemClasses" to all the "system" classes and loaders;
// "SO_Symbols" applies the closure to all entries in SymbolsTable;
// "SO_Strings" applies the closure to all entries in StringTable;
// "SO_CodeCache" applies the closure to all elements of the CodeCache.
void process_strong_roots(bool activate_scope,