{"id":2598,"date":"2025-06-06T09:28:13","date_gmt":"2025-06-06T09:28:13","guid":{"rendered":"https:\/\/diznr.com\/?p=2598"},"modified":"2025-06-06T09:28:13","modified_gmt":"2025-06-06T09:28:13","slug":"logical-clock-lamport-clock-and-vector-clock-in-distributed-system-logical-time-lamports-and-algorithm-vector","status":"publish","type":"post","link":"https:\/\/www.reilsolar.com\/pdf\/logical-clock-lamport-clock-and-vector-clock-in-distributed-system-logical-time-lamports-and-algorithm-vector\/","title":{"rendered":"Logical Clock: Lamport Clock and Vector Clock in Distributed System – Logical Time-Lamport’s and Vector Algorithm"},"content":{"rendered":"

Logical Clock: Lamport Clock and Vector Clock in Distributed System – Logical Time-Lamport’s and Vector Algorithm. Lampor’t Clock and Vector Clock With Algorithm in Distributed System.<\/p>\n

[fvplayer id=”79″]<\/p>\n

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Logical Clocks: Lamport Clock and Vector Clock in Distributed Systems<\/strong><\/h3>\n

In distributed systems<\/strong>, there is no global clock to keep track of events, so we use logical clocks<\/strong> to maintain the ordering of events. Two widely used logical clocks are:<\/p>\n

    \n
  1. Lamport Timestamps (Lamport Clock)<\/strong><\/li>\n
  2. Vector Clocks<\/strong><\/li>\n<\/ol>\n

    Let\u2019s dive into how they work and their differences.<\/p>\n

    1. What is a Logical Clock?<\/strong><\/h3>\n

    A logical clock<\/strong> is a mechanism to assign timestamps to events in a distributed system without relying on physical clocks<\/strong>. It helps to maintain event order<\/strong> across different processes.<\/p>\n

    Two key conditions for logical clocks:<\/strong>
    Causal Order Condition<\/strong>: If an event A<\/strong> happens before event B<\/strong>, then timestamp(A) < timestamp(B)<\/strong>.
    Consistency<\/strong>: The logical clock must be consistent with the actual order of events in a system.<\/p>\n

    2. Lamport Clock (Lamport Timestamps)<\/strong><\/h3>\n

    Concept<\/strong><\/h3>\n

    \u00a0Proposed by Leslie Lamport (1978)<\/strong>, the Lamport Clock<\/strong> provides a way to order events<\/strong> in a distributed system.
    \u00a0It does not<\/strong> detect concurrent events<\/strong>.
    \u00a0Every process maintains a counter that is incremented for each event<\/strong> and synchronized using message passing.<\/p>\n

    Lamport’s Algorithm (Step-by-Step)<\/strong><\/h3>\n

    1. Initialization:<\/strong><\/h4>\n

    Each process P<\/strong> maintains a logical clock L(P)<\/strong>, initialized to 0<\/strong>.<\/p>\n

    2. Event Execution:<\/strong><\/h4>\n

    Whenever a process executes an event<\/strong>, it increments its clock<\/strong>:<\/p>\n

    L(P)=L(P)+1L(P) = L(P) + 1<\/span>L<\/span>(<\/span>P<\/span>)<\/span>=<\/span><\/span>L<\/span>(<\/span>P<\/span>)<\/span>+<\/span><\/span>1<\/span><\/span><\/span><\/span><\/span><\/p>\n

    3. Sending a Message:<\/strong><\/h4>\n

    When a process P sends a message<\/strong> to another process Q<\/strong>, it includes its current timestamp<\/strong> in the message:<\/p>\n

    M(T)=L(P)M(T) = L(P)<\/span>M<\/span>(<\/span>T<\/span>)<\/span>=<\/span><\/span>L<\/span>(<\/span>P<\/span>)<\/span><\/span><\/span><\/span><\/span><\/p>\n

    4. Receiving a Message:<\/strong><\/h4>\n

    When process Q<\/strong> receives a message M(T)<\/strong> from process P<\/strong>, it updates its clock<\/strong> as:<\/p>\n

    L(Q)=max\u2061(L(Q),M(T))+1L(Q) = \\max(L(Q), M(T)) + 1<\/span>L<\/span>(<\/span>Q<\/span>)<\/span>=<\/span><\/span>max<\/span>(<\/span>L<\/span>(<\/span>Q<\/span>)<\/span>,<\/span>M<\/span>(<\/span>T<\/span>))<\/span>+<\/span><\/span>1<\/span><\/span><\/span><\/span><\/span><\/p>\n

    Example of Lamport Timestamps<\/strong><\/h3>\n

    Consider three processes (P1, P2, P3)<\/strong> with events labeled as A, B, C, etc.<\/p>\n

    Initial State:<\/strong><\/h4>\n
    \n\n\n\n\n\n\n\n
    Event<\/th>\nP1<\/th>\nP2<\/th>\nP3<\/th>\n<\/tr>\n<\/thead>\n
    A<\/td>\n1<\/td>\n<\/td>\n<\/td>\n<\/tr>\n
    B<\/td>\n<\/td>\n1<\/td>\n<\/td>\n<\/tr>\n
    C<\/td>\n<\/td>\n<\/td>\n1<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n

    Message Passing & Timestamp Updates<\/strong><\/h4>\n

    P1 sends message M1 to P2:<\/strong><\/p>\n