RFR (xs) 8145940: TempNewSymbol should have correct copy and assignment functions
coleen.phillimore at oracle.com
Thu Jan 7 20:02:41 UTC 2016
Summary: Add clear() to the assignment operator and add copy constructor.
Ran all jtreg, colocated and non-colocated tests. RunThese -jck with
Percent removed 1.35
Reference counts 194583
Percent removed 1.53
Reference counts 194245
Without a reference counting copy constructor, we could remove a
TempNewSymbol's Symbol if a GC happens. Consider:
TempNewSymbol ts = SymbolTable::new_symbol("abc");
// Hit GC
The ref count for "abc" is 1 when created by new_symbol, and the
destructor could run after the copy into ts, decrementing the reference
count to 0 again. GC could unlink that symbol from the symbol table.
Fortunately, we haven't seen this bug.
open webrev at http://cr.openjdk.java.net/~coleenp/8145940/
bug link https://bugs.openjdk.java.net/browse/JDK-8145940
More information about the hotspot-runtime-dev