Snapshot algorithm
Under snapshot algorithm or distributed snapshot of a process is understood to be used to determine a global state of an active distributed system. It was developed by Leslie Lamport and K. Mani Chandy and is therefore also known as the Chandy - Lamport algorithm.
Assumptions
For the algorithm, the following assumptions are made:
- Errors are excluded, sent messages only once
- The communication channel has a direction and is arranged according to the FIFO principle,
- There is a communication path between any pair of processes in the system
- Any process can initiate the algorithm
- The algorithm has no impact on the normal execution of the process
- Each process in the system records its local state and the state herführender channels on
Expiration
The process that starts the Schnappschussalgortihmus, creates a snapshot of its local state and sends a marker at each continued leading channel. Upon receipt of a marker message there are two possibilities:
By this method, both the actual states of the processes and messages between processes are recorded.