| 摘要 |
<p>One embodiment of the present invention provides a system that uses a time stamp in order to more efficiently mark objects to keep track of accesses to fields with the objects. Upon receiving a first reference to a first field in an object, the system determines whether the first field has been accessed within a current time period. The system does so by retrieving a time stamp associated with the object. This time stamp indicates the last time any marking bit associated with any field in the object was updated. The system compares the time stamp with a current time value associated with the current time period. The system additionally retrieves a first marking bit associated with the first field and determines if the first marking bit is set. If the first marking bit is set and if the time stamp equals the current time value, the system determines that the first field has been accessed in the current time period. In one embodiment of the present invention, the system indicates that a second field in the object has been accessed in the current time period upon receiving a second reference to the second field. In response to the second reference, the system sets a second marking bit associated with the second field. The system also updates the time stamp associated with the object, if necessary, so that the time stamp contains the current time value.</p> |
