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8270489: Support archived heap objects in EpsilonGC

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Reviewed-by: shade, ccheung
This commit is contained in:
Ioi Lam 2021-09-01 16:50:11 +00:00
parent dacd197897
commit 655ea6d42a
31 changed files with 771 additions and 120 deletions
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49
src/hotspot/share/classfile/stringTable.cpp
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@ -72,11 +72,12 @@ inline oop read_string_from_compact_hashtable(address base_address, u4 offset) {
return HeapShared::decode_from_archive(v);
}
static CompactHashtable<
typedef CompactHashtable<
const jchar*, oop,
read_string_from_compact_hashtable,
java_lang_String::equals
> _shared_table;
java_lang_String::equals> SharedStringTable;
static SharedStringTable _shared_table;
#endif
// --------------------------------------------------------------------------
@ -761,7 +762,7 @@ public:
};
void StringTable::write_to_archive(const DumpedInternedStrings* dumped_interned_strings) {
assert(HeapShared::is_heap_object_archiving_allowed(), "must be");
assert(HeapShared::can_write(), "must be");
_shared_table.reset();
CompactHashtableWriter writer(_items_count, ArchiveBuilder::string_stats());
@ -779,9 +780,47 @@ void StringTable::serialize_shared_table_header(SerializeClosure* soc) {
if (soc->writing()) {
// Sanity. Make sure we don't use the shared table at dump time
_shared_table.reset();
} else if (!HeapShared::closed_regions_mapped()) {
} else if (!HeapShared::are_archived_strings_available()) {
_shared_table.reset();
}
}
class SharedStringTransfer {
JavaThread* _current;
public:
SharedStringTransfer(JavaThread* current) : _current(current) {}
void do_value(oop string) {
JavaThread* THREAD = _current;
ExceptionMark rm(THREAD);
HandleMark hm(THREAD);
StringTable::intern(string, THREAD);
if (HAS_PENDING_EXCEPTION) {
// The archived constant pools contains strings that must be in the interned string table.
// If we fail here, it means the VM runs out of memory during bootstrap, so there's no point
// of trying to recover from here.
vm_exit_during_initialization("Failed to transfer shared strings to interned string table");
}
}
};
// If the CDS archive heap is loaded (not mapped) into the old generation,
// it's possible for the shared strings to move due to full GC, making the
// _shared_table invalid. Therefore, we proactively copy all the shared
// strings into the _local_table, which can deal with oop relocation.
void StringTable::transfer_shared_strings_to_local_table() {
assert(HeapShared::is_loaded(), "must be");
EXCEPTION_MARK;
// Reset _shared_table so that during the transfer, StringTable::intern()
// will not look up from there. Instead, it will create a new entry in
// _local_table for each element in shared_table_copy.
SharedStringTable shared_table_copy = _shared_table;
_shared_table.reset();
SharedStringTransfer transfer(THREAD);
shared_table_copy.iterate(&transfer);
}
#endif //INCLUDE_CDS_JAVA_HEAP