Importance

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Abstract

A checkpoint and restoration system is disclosed to provide checkpoint and restoration techniques for user application processes which save the process state, including the volatile state and desired portions of the persistent state, during normal execution, and thereafter restore the saved state. A lazy checkpoint technique is disclosed which delays the taking of the persistent state checkpoint until an inconsistency between the checkpointed volatile state and a portion of the persistent state is about to occur. The disclosed checkpoint and restoration system allows a user or a user application process to specify selected portions of the persistent state to be excluded from a checkpoint. A selected portion of the pre-restoring process state, such as a return value argument, may be protected before restoring the user application process to a checkpointed state, so that the pre-restoration values of the protected state are retained following restoration of the checkpoint. The retained return value allows one or more segments of restoration code to be executed following a restoration and a normal execution mode to be distinguished from a restoration mode.

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First Claim