output: #fixed code
                                  public boolean execute(String sql) throws SQLException {
          internalClose();
  
          SQLExtension ext = ExtendedCommand.parse(sql);
          if (ext != null) { 
              ext.execute(db);
  
              return false;
          }
  
          this.sql = sql;
  
          db.prepare(this);
          return exec();
      }
input: #vulnerable code 
                                  public boolean execute(String sql) throws SQLException {
          internalClose();
  
          SQLExtension ext = ExtendedCommand.parse(sql);
          if (ext != null) { 
              ext.execute(db);
  
              return false;
          }
  
          this.sql = sql;
  
          boolean success = false;
          try {
              db.prepare(this);
              final boolean result = exec();
              success = true;
              return result;
          } finally {
              if (!success) {
                  internalClose();
              }
          }
      } 
                              #location 2 
                              #vulnerability type THREAD_SAFETY_VIOLATION