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8180048: Interned string and symbol table leak memory during parallel unlinking

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Make appending found dead BasicHashtableEntrys to the free list atomic.

Reviewed-by: ehelin, shade, coleenp
This commit is contained in:
Thomas Schatzl 2017-05-15 12:20:15 +02:00
parent 8e28d5772d
commit c775f6f58b
7 changed files with 97 additions and 29 deletions
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35
hotspot/src/share/vm/classfile/symbolTable.cpp
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@ -1,5 +1,5 @@
/*
* Copyright (c) 1997, 2016, Oracle and/or its affiliates. All rights reserved.
* Copyright (c) 1997, 2017, Oracle and/or its affiliates. All rights reserved.
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
* This code is free software; you can redistribute it and/or modify it
@ -98,7 +98,7 @@ int SymbolTable::_symbols_removed = 0;
int SymbolTable::_symbols_counted = 0;
volatile int SymbolTable::_parallel_claimed_idx = 0;
void SymbolTable::buckets_unlink(int start_idx, int end_idx, int* processed, int* removed) {
void SymbolTable::buckets_unlink(int start_idx, int end_idx, BucketUnlinkContext* context) {
for (int i = start_idx; i < end_idx; ++i) {
HashtableEntry<Symbol*, mtSymbol>** p = the_table()->bucket_addr(i);
HashtableEntry<Symbol*, mtSymbol>* entry = the_table()->bucket(i);
@ -111,15 +111,14 @@ void SymbolTable::buckets_unlink(int start_idx, int end_idx, int* processed, int
break;
}
Symbol* s = entry->literal();
(*processed)++;
context->_num_processed++;
assert(s != NULL, "just checking");
// If reference count is zero, remove.
if (s->refcount() == 0) {
assert(!entry->is_shared(), "shared entries should be kept live");
delete s;
(*removed)++;
*p = entry->next();
the_table()->free_entry(entry);
context->free_entry(entry);
} else {
p = entry->next_addr();
}
@ -132,17 +131,20 @@ void SymbolTable::buckets_unlink(int start_idx, int end_idx, int* processed, int
// Remove unreferenced symbols from the symbol table
// This is done late during GC.
void SymbolTable::unlink(int* processed, int* removed) {
size_t memory_total = 0;
buckets_unlink(0, the_table()->table_size(), processed, removed);
_symbols_removed += *removed;
_symbols_counted += *processed;
BucketUnlinkContext context;
buckets_unlink(0, the_table()->table_size(), &context);
_the_table->bulk_free_entries(&context);
*processed = context._num_processed;
*removed = context._num_removed;
_symbols_removed = context._num_removed;
_symbols_counted = context._num_processed;
}
void SymbolTable::possibly_parallel_unlink(int* processed, int* removed) {
const int limit = the_table()->table_size();
size_t memory_total = 0;
BucketUnlinkContext context;
for (;;) {
// Grab next set of buckets to scan
int start_idx = Atomic::add(ClaimChunkSize, &_parallel_claimed_idx) - ClaimChunkSize;
@ -152,10 +154,15 @@ void SymbolTable::possibly_parallel_unlink(int* processed, int* removed) {
}
int end_idx = MIN2(limit, start_idx + ClaimChunkSize);
buckets_unlink(start_idx, end_idx, processed, removed);
buckets_unlink(start_idx, end_idx, &context);
}
Atomic::add(*processed, &_symbols_counted);
Atomic::add(*removed, &_symbols_removed);
_the_table->bulk_free_entries(&context);
*processed = context._num_processed;
*removed = context._num_removed;
Atomic::add(context._num_processed, &_symbols_counted);
Atomic::add(context._num_removed, &_symbols_removed);
}
// Create a new table and using alternate hash code, populate the new table