LOGICAL CLOCK IN DISTRIBUTED SYSTEM HAPPENED BEFORE CLOCK CLOCK SYNC CLOCK VECTOR.<\/p>\n
Distributed Systems Physical Clocks Logical Clocks Vector Clocks Synchronize Physical Clocks Logical Time Happened Before Clocks Linear Time Distributed Systems Physical Clocks Logical Clocks Vector Clocks.<\/span><\/p>\n [fvplayer id=”81″]<\/p>\n Synchronize Physical Clocks Logical Time Happened Before Linear Time Time Ordering Module Vector Clock Vs Lamport Clock Logical Clock In Distributed System What Is Global Clock In Distributed System. Vector Clock In Distributed System Types Of Clocks In Distributed System Physical Clocks Logical Clocks Vector Clocks Synchronize Physical Clocks Logical Time Happened Before Linear Time Time Ordering Module Vector Clock Vs Lamport Clock. Logical Clock in Distributed System. What Is Global Clock In Distributed System Vector Clock In Distributed System Types Of Clocks In Distributed System Time Ordering Module. Vector Clock Vs Lamport Clock Logical Clock In Distributed System What Is Global Clock In Distributed System Vector Clock In Distributed System Types Of Clocks In Distributed System.<\/span><\/p>\n Here’s a clear and concise explanation of Logical Clocks<\/strong> in Distributed Systems, including concepts like Happened-Before Relation<\/strong>, Lamport Clock<\/strong>, Vector Clock<\/strong>, and Clock Synchronization<\/strong>.<\/p>\n In distributed systems, there\u2019s no global clock<\/strong>. So, we use logical clocks<\/strong> to order events correctly across multiple processes (nodes).<\/p>\n This defines a partial order<\/strong> of events.<\/p>\n \ud83d\udccc Definition:<\/strong><\/p>\n If A and B are events<\/strong> in the same process and A occurs before B \u2192 If A is sending a message<\/strong> and B is receiving the same<\/strong> \u2192 If Purpose:<\/strong> Establish a cause-effect relationship between events in different processes.<\/p>\n Goal:<\/strong> Assign numbers (timestamps) to events to maintain \ud83d\udccc Rules:<\/strong><\/p>\n Each process maintains a local clock (initially 0).<\/p>\n<\/li>\n Before executing any event, increment the clock: When sending a message, send timestamp with it.<\/p>\n<\/li>\n On receiving a message with timestamp Limitation:<\/strong><\/p>\n It can say one event happened before another but not if two events are concurrent<\/strong>.<\/p>\n<\/li>\n<\/ul>\n Goal:<\/strong> Detect causal relationships<\/strong> and concurrent events<\/strong> accurately.<\/p>\n \ud83d\udccc How it works:<\/strong><\/p>\n Each process keeps a vector Before event: On sending message, send vector.<\/p>\n<\/li>\n On receiving message with vector For all \ud83d\udd0d Comparison:<\/strong><\/p>\n Event A happened before<\/strong> B \u21e8 Events concurrent<\/strong> \u21e8 Since there’s no common clock:<\/p>\n NTP (Network Time Protocol):<\/strong> Sync real clocks (physical)<\/p>\n<\/li>\n Cristian\u2019s Algorithm:<\/strong> Get time from time server (1 request)<\/p>\n<\/li>\n Berkeley Algorithm:<\/strong> Average times across nodes<\/p>\n<\/li>\n<\/ul>\n These aim to reduce clock drift<\/strong> and keep system-wide time in sync<\/strong>, though not perfect.<\/p>\n
\n\ud83d\udd52 LOGICAL CLOCK IN DISTRIBUTED SYSTEMS<\/h2>\n
\n\ud83d\udd04 1. Happened-Before Relation (\u2192)<\/strong> \u2013 by Leslie Lamport<\/em><\/h3>\n
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A \u2192 B<\/code><\/p>\n<\/li>\nA \u2192 B<\/code><\/p>\n<\/li>\nA \u2192 B<\/code> and B \u2192 C<\/code> \u2192 then A \u2192 C<\/code> (transitivity)<\/p>\n<\/li>\n<\/ul>\n
\n\u23f1\ufe0f 2. Lamport\u2019s Logical Clock (Scalar Clock)<\/strong><\/h3>\n
A \u2192 B \u21d2 timestamp(A) < timestamp(B)<\/code><\/p>\n\n
C := C + 1<\/code><\/p>\n<\/li>\nT<\/code>, set:C := max(C, T) + 1<\/code><\/p>\n<\/li>\n<\/ol>\n\n
\n\ud83e\udded 3. Vector Clocks<\/strong><\/h3>\n
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V[i]<\/code> of size n<\/code> (number of processes).<\/p>\n<\/li>\nV[i] := V[i] + 1<\/code><\/p>\n<\/li>\nV'<\/code>:<\/p>\n\n
V[i] := V[i] + 1<\/code><\/p>\n<\/li>\nj \u2260 i<\/code>, V[j] := max(V[j], V'[j])<\/code><\/p>\n<\/li>\n<\/ul>\n<\/li>\n<\/ul>\n\n
V(A) < V(B)<\/code> (element-wise)<\/p>\n<\/li>\nV(A)<\/code> and V(B)<\/code> are not comparable<\/strong><\/p>\n<\/li>\n<\/ul>\n
\n\ud83d\udd70\ufe0f 4. Clock Synchronization<\/strong><\/h3>\n
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\n\ud83d\udcca Summary Table<\/h3>\n