优化变成了忧患：String类的split方法引起的内存泄漏

class StringTable : public Hashtable {
  // ...
private:
  // The string table
  static StringTable* _the_table;

  // ...

  // Table size
  enum {
    string_table_size = 1009
  };
  
  // ...

public:
  // The string table
  static StringTable* the_table() { return _the_table; }

  // ...
  
  // GC support
  //   Delete pointers to otherwise-unreachable objects.
  static void unlink(BoolObjectClosure* cl) {
    the_table()->Hashtable::unlink(cl);
  }
  
  // ...
};

// GC support

void Hashtable::unlink(BoolObjectClosure* is_alive) {
  // Readers of the table are unlocked, so we should only be removing
  // entries at a safepoint.
  assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint");
  for (int i = 0; i < table_size(); ++i) {
    for (HashtableEntry** p = bucket_addr(i); *p != NULL; ) {
      HashtableEntry* entry = *p;
      if (entry->is_shared()) {
        break;
      }
      assert(entry->literal() != NULL, "just checking");
      if (is_alive->do_object_b(entry->literal())) {
        p = entry->next_addr();
      } else {
        *p = entry->next();
        free_entry(entry);
      }
    }
  }
}