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The Lamport timestamp algorithm is a simple logical clock algorithm used to determine the order of events in a distributed computer system.As different nodes or processes will typically not be perfectly synchronized, this algorithm is used to provide a partial ordering of events with minimal overhead, and conceptually provide a starting point for the more advanced vector clock method.
Just as in Lamport timestamps, inter-process messages contain the state of the sending process's logical clock. A vector clock of a system of N processes is an array /vector of N logical clocks, one clock per process; a local "largest possible values" copy of the global clock-array is kept in each process.
Common examples of this type of timestamp are a postmark on a letter or the "in" and "out" times on a time card. With the advent of digital data systems, the term has expanded to refer to digital date and time information attached to digital data.
Requesting process. Pushing its request in its own queue (ordered by time stamps) Sending a request to every node. Waiting for replies from all other nodes.
[a] Thus, a signed 32-bit integer can only represent integer values from −(2 31) to 2 31 − 1 inclusive. Consequently, if a signed 32-bit integer is used to store Unix time, the latest time that can be stored is 2 31 − 1 (2,147,483,647) seconds after epoch, which is 03:14:07 on Tuesday, 19 January 2038. [ 7 ]
If the resolution of the timestamp is too large (coarse), the possibility of two or more timestamps being equal is increased and thus enabling some transactions to commit out of correct order. For example, for a system that creates one hundred unique timestamps per second, two events that occur 2 milliseconds apart may be given the same ...
[1] [2] For instance, a heartbeat network uses timestamping to monitor the nodes on a high availability computer cluster. [ 3 ] Timestamping computer files (updating the timestamp in the per-file metadata every time a file is modified) makes it possible to use efficient build automation tools.
Software timekeeping systems vary widely in the resolution of time measurement; some systems may use time units as large as a day, while others may use nanoseconds.For example, for an epoch date of midnight UTC (00:00) on 1 January 1900, and a time unit of a second, the time of the midnight (24:00) between 1 January 1900 and 2 January 1900 is represented by the number 86400, the number of ...