Author Archives: Shanoj

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About Shanoj

Author : Shanoj is a Data engineer and solutions architect passionate about delivering business value and actionable insights through well-architected data products. He holds several certifications on AWS, Oracle, Apache, Google Cloud, Docker, Linux and focuses on data engineering and analysis using SQL, Python, BigData, RDBMS, Apache Spark, among other technologies. He has 17+ years of history working with various technologies in the Retail and BFS domains.

Distributed Systems Design Pattern: Two-Phase Commit (2PC) for Transaction Consistency [Banking…

The Two-Phase Commit (2PC) protocol is a fundamental distributed systems design pattern that ensures atomicity in transactions across multiple nodes. It enables consistent updates in distributed databases, even in the presence of node failures, by coordinating between participants using a coordinator node.

In this article, we’ll explore how 2PC works, its application in banking systems, and its practical trade-offs, focusing on the use case of multi-account money transfers.

The Problem:

In distributed databases, transactions involving multiple nodes can face challenges in ensuring consistency. For example:

  • Partial Updates: One node completes the transaction, while another fails, leaving the system in an inconsistent state.
  • Network Failures: Delays or lost messages can disrupt the transaction’s atomicity.
  • Concurrency Issues: Simultaneous transactions might violate business constraints, like overdrawing an account.

Example Problem Scenario

In a banking system, transferring $1,000 from Account A (Node 1) to Account B (Node 2) requires both accounts to remain consistent. If Node 1 successfully debits Account A but Node 2 fails to credit Account B, the system ends up with inconsistent account balances, violating atomicity.

Two-Phase Commit Protocol: How It Works

The Two-Phase Commit Protocol addresses these issues by ensuring that all participating nodes either commit or abort a transaction together. It achieves this in two distinct phases:

Phase 1: Prepare

  1. The Transaction Coordinator sends a “Prepare” request to all participating nodes.
  2. Each node validates the transaction (e.g., checking constraints like sufficient balance).
  3. Nodes respond with either a “Yes” (ready to commit) or “No” (abort).

Phase 2: Commit or Abort

  1. If all nodes vote “Yes,” the coordinator sends a “Commit” message, and all nodes apply the transaction.
  2. If any node votes “No,” the coordinator sends an “Abort” message, rolling back any changes.
The diagram illustrates the Two-Phase Commit (2PC) protocol, ensuring transaction consistency across distributed systems. In the Prepare Phase, the Transaction Coordinator gathers validation responses from participant nodes. If all nodes validate successfully (“Yes” votes), the transaction moves to the Commit Phase, where changes are committed across all nodes. If any node fails validation (“No” vote), the transaction is aborted, and changes are rolled back to maintain consistency and atomicity. This process guarantees a coordinated outcome, either committing or aborting the transaction uniformly across all nodes.

Problem Context

Let’s revisit the banking use case:

Prepare Phase:

  • Node 1 prepares to debit $1,000 from Account A and logs the operation.
  • Node 2 prepares to credit $1,000 to Account B and logs the operation.
  • Both nodes validate constraints (e.g., ensuring sufficient balance in Account A).

Commit Phase:

  • If both nodes respond positively, the coordinator instructs them to commit.
  • If either node fails validation, the transaction is aborted, and any changes are rolled back.

Fault Recovery in Two-Phase Commit

What happens when failures occur?

  • If a participant node crashes during the Prepare Phase, the coordinator aborts the transaction.
  • If the coordinator crashes after sending a “Prepare” message but before deciding to commit or abort, the nodes enter an uncertain state until the coordinator recovers.
  • A Replication Log ensures that the coordinator’s decision can be recovered and replayed after a crash.

Practical Considerations and Trade-Offs

Advantages:

  1. Strong Consistency: Ensures all-or-nothing outcomes for transactions.
  2. Coordination: Maintains atomicity across distributed nodes.
  3. Error Handling: Logs allow recovery after failures.

Challenges:

  1. Blocking: Nodes remain in uncertain states if the coordinator crashes.
  2. Network Overhead: Requires multiple message exchanges.
  3. Latency: Transaction delays due to prepare and commit phases.

The Two-Phase Commit Protocol is a robust solution for achieving transactional consistency in distributed systems. It ensures atomicity and consistency, making it ideal for critical applications like banking, where even minor inconsistencies can have significant consequences.

By coordinating between participant nodes and enforcing consensus, 2PC eliminates the risk of partial updates, providing a foundation for reliable distributed transactions.

Thank you for being a part of the community

Before you go:

Day -3: Book Summary Notes [Designing Data-Intensive Applications]

Chapter 3: “Storage and Retrieval”

As part of revisiting one of the tech classics, ‘Designing Data-Intensive Applications’, I prepared these detailed notes to reinforce my understanding and share them with close friends. Recently, I thought — why not share them here? Maybe they’ll benefit more people who are diving into the depths of distributed systems and data-intensive designs! 🌟

A Quick Note: These are not summaries of the book but rather personal notes from specific chapters I recently revisited. They focus on topics I found particularly meaningful, written in my way of absorbing and organizing information.

Day -2: Book Summary Notes [Designing Data-Intensive Applications]

Chapter 2: “Data Models and Query Languages”

As part of revisiting one of the tech classics, ‘Designing Data-Intensive Applications’, I prepared these detailed notes to reinforce my understanding and share them with close friends. Recently, I thought — why not share them here? Maybe they’ll benefit more people who are diving into the depths of distributed systems and data-intensive designs! 🌟

A Quick Note: These are not summaries of the book but rather personal notes from specific chapters I recently revisited. They focus on topics I found particularly meaningful, written in my way of absorbing and organizing information.

Day -1: Book Summary Notes [Designing Data-Intensive Applications]

Chapter 1: Reliable, Scalable, & Maintainable Applications

As part of revisiting one of the tech classics, ‘Designing Data-Intensive Applications’, I prepared these detailed notes to reinforce my understanding and share them with close friends. Recently, I thought — why not share them here? Maybe they’ll benefit more people who are diving into the depths of distributed systems and data-intensive designs! 🌟

A Quick Note: These are not summaries of the book but rather personal notes from specific chapters I recently revisited. They focus on topics I found particularly meaningful, written in my way of absorbing and organizing information.

Machine Learning Basics: Pattern Recognition Systems

This diagram illustrates the flow of a pattern recognition system, starting from collecting data in the real world, captured via sensors. The data undergoes preprocessing to remove noise and enhance quality before being converted into a structured, numerical format for further analysis. The system then applies machine learning algorithms for tasks such as classification, clustering, or regression, depending on the problem at hand. The final output or results are generated after the system processes the data through these stages.

Pattern recognition is an essential technology that plays a crucial role in automating processes and solving real-time problems across various domains. From facial recognition on social media platforms to predictive analytics in e-commerce, healthcare, and autonomous vehicles, pattern recognition algorithms have revolutionized the way we interact with technology. This article will guide you through the core stages of pattern recognition systems, highlight machine learning concepts, and demonstrate how these algorithms are applied to real-world problems.

Introduction to Pattern Recognition Systems

Pattern recognition refers to the identification and classification of patterns in data. These patterns can range from simple shapes or images to complex signals in speech or health diagnostics. Just like humans identify patterns intuitively — such as recognizing a friend’s face in a crowd or understanding speech from context — machines can also learn to identify patterns in data through pattern recognition systems. These systems use algorithms, including machine learning models, to automate the process of pattern identification.

Real-World Applications of Pattern Recognition
Pattern recognition is integral to a range of real-time applications:

  • Social Media: Platforms like Facebook use pattern recognition to automatically identify and tag people in images.
  • Virtual Assistants: Google Assistant recognizes speech commands and responds appropriately.
  • E-commerce: Recommendation systems suggest products based on the user’s past behavior and preferences.
  • Healthcare: During the COVID-19 pandemic, predictive applications analyzed lung scans to assess the likelihood of infection.
  • Autonomous Vehicles: Driverless cars use sensors and machine learning models to navigate roads safely.

These applications are underpinned by powerful pattern recognition systems that extract insights from data, enabling automation, personalization, and improved decision-making.

Stages of a Pattern Recognition System

This diagram depicts the workflow for building a machine learning system. It begins with the selection of data from various providers. The data undergoes preprocessing to ensure quality and consistency. Then, machine learning algorithms are applied iteratively to create candidate models. The best-performing model (the Golden Model) is selected and deployed for real-world applications. The diagram highlights the iterative process of model improvement and deployment.

Pattern recognition systems generally follow a multi-step process, each essential for transforming raw data into meaningful insights. Let’s dive into the core stages involved:

1. Data Collection from the Real World

The first step involves gathering raw data from the environment. This data can come from various sources such as images, audio, video, or sensor readings. For instance, in the case of face recognition, cameras capture images that are then processed by the system.

2. Preprocessing and Enhancement

Raw data often contains noise or inconsistencies, which can hinder accurate pattern recognition. Therefore, preprocessing is crucial. This stage includes steps such as noise removal, normalization, and handling missing data. For example, in image recognition, preprocessing might involve adjusting lighting conditions or cropping out irrelevant parts of the image.

3. Feature Extraction

Once the data is cleaned, it is passed through feature extraction algorithms. These algorithms transform the raw data into numerical representations that machine learning models can work with. For example, in speech recognition, feature extraction might convert audio signals into frequency components or spectrograms.

4. Model Training Using Machine Learning Algorithms

At this stage, machine learning algorithms are employed to identify patterns in the data. The data is split into training and test sets. The training data is used to train the model, while the test data is kept aside to evaluate the model’s performance.

5. Feedback/Adaptation

Machine learning models are not perfect on their first try. Feedback and adaptation allow the system to improve iteratively. The model can be retrained using new data, adjusted parameters, or even different algorithms to enhance its accuracy and robustness.

6. Classification, Clustering, or Regression

After training, the model is ready to classify new data or predict outcomes. Depending on the problem at hand, different machine learning tasks are applied:

  • Classification: This task involves assigning data points to predefined classes. For example, categorizing emails as spam or not spam.
  • Clustering: Unsupervised learning algorithms group data points based on similarity without predefined labels. A typical use case is market segmentation.
  • Regression: This task predicts continuous values, such as forecasting stock prices or temperature.

Machine Learning Pipeline

The ML pipeline is an essential component of pattern recognition systems. The pipeline encompasses all stages of data processing, from collection to model deployment. It follows a structured approach to ensure the model is robust, accurate, and deployable in real-world scenarios.

This diagram showcases the end-to-end process in a machine learning pipeline. It begins with data collection, which is split into training and test datasets. The training data is used to train the machine learning model, while the test data is reserved for evaluating the model’s performance. After training, the model is assessed for accuracy, and if it performs well, it becomes the final deployed model.

Case Studies and Use Cases

To better understand the application of pattern recognition, let’s explore a few case studies:

Case Study 1: Automated Crop Disease Detection in Agriculture

Consider a system designed to identify diseases in crops using images taken by drones or satellite cameras. The system captures high-resolution images of crops in the field, processes these images to enhance quality (e.g., adjusting for lighting or shadows), and then extracts features such as leaf patterns or color changes. A machine learning model is trained to classify whether the crop is healthy or diseased. After training, the system can automatically detect disease outbreaks, alerting farmers to take necessary action.

Case Study 2: Fraud Detection in Financial Transactions

Pattern recognition systems are widely used in fraud detection, where algorithms monitor financial transactions to spot unusual patterns that may indicate fraudulent activity. For example, a credit card company uses a pattern recognition system to analyze purchasing behavior. If a customer’s recent transaction history differs significantly from their normal behavior, the system flags the transaction for review. Machine learning models help continuously improve the accuracy of fraud detection as they learn from new transaction data.

Case Study 3: Traffic Flow Optimization in Smart Cities

In modern cities, traffic signals are increasingly controlled by machine learning systems to optimize traffic flow. Cameras and sensors at intersections continuously capture traffic data. This data is processed and analyzed to adjust signal timings dynamically, ensuring that traffic moves smoothly during rush hours. By using pattern recognition algorithms, these systems can predict traffic patterns and reduce congestion, improving both efficiency and safety.


Pattern recognition and machine learning algorithms are transforming industries by enabling automation, enhancing decision-making, and creating innovative solutions to real-world challenges. Whether it’s classifying images, predicting future outcomes, or identifying clusters of data, these systems are essential for tasks that require human-like cognitive abilities.

The real power of pattern recognition systems lies in their ability to continuously improve, adapt, and provide accurate insights as more data becomes available.

Thank you for being a part of the community

Before you go:

Distributed Design Pattern: State Machine Replication [IoT System Monitoring Use Case]

The diagram illustrates a distributed state machine replication process for Industrial IoT systems. Sensor data from distributed nodes is ingested into a primary node and propagated to replicas via an event stream (e.g., Kafka). A consensus mechanism ensures consistent state transitions, while a robust error-handling mechanism detects node failures and replays replication logs to maintain system consistency.

Industrial IoT (IIoT) systems depend on accurate, synchronized state management across distributed nodes to ensure seamless monitoring and fault tolerance. The Distributed State Machine Replication pattern ensures consistency in state transitions across all nodes, enabling fault recovery and high availability.

The Problem:

In IIoT environments, state management is critical for monitoring and controlling devices such as factory machinery, sensors, and robotic arms. However, maintaining consistency across distributed systems presents unique challenges:

  1. State Inconsistency: Nodes may fail to apply or propagate updates, leading to diverging states.
  2. Fault Tolerance: System failures must not result in incomplete or incorrect system states.
  3. Scalability: As devices scale across factories, ensuring synchronization becomes increasingly complex.
The diagram illustrates the problem of state inconsistency in IIoT systems due to the lack of synchronized state validation. Sensor Node 1 detects a high temperature alert and sends it to Node A, which initiates an overheating detection and triggers a shutdown. Meanwhile, Sensor Node 2 fails to detect the event, resulting in Node B taking no action. The lack of validation across nodes leads to conflicting actions, delayed system responses, and operational risks, highlighting the need for consistent state synchronization.

Example Problem Scenario:
In a manufacturing plant, a temperature sensor sends an alert indicating that a machine’s temperature has exceeded the safe threshold. If one node processes the alert and another misses it due to a network issue, corrective actions may not be triggered in time, resulting in system failure or downtime.

Distributed State Machine Replication

The Distributed State Machine Replication pattern ensures that all nodes maintain identical states by synchronizing state transitions across the network.

Key Features:

  1. State Machine Abstraction: Each node runs a replicated state machine, processing the same state transitions in the same order.
  2. Consensus Protocol: Protocols like Raft or Paxos ensure that all nodes agree on each state transition.
  3. Log-Based Updates: Updates are logged and replayed on all nodes to maintain a consistent state.
The diagram illustrates how Distributed State Machine Replication ensures consistent state management in IIoT systems. Sensor Nodes send updates to a Primary Node, which coordinates with Replica Nodes (e.g., Node A, Node B, Node C) using a Consensus Protocol to validate and apply state transitions. Upon reaching consensus, updates are logged to the Database and propagated via an Event Stream to downstream systems, ensuring all nodes and systems remain synchronized. In case of failures, the Log Errors & Retry mechanism prevents partial or inconsistent state transitions, while operators are notified, and system states are actively monitored for proactive resolution. This approach ensures reliability, consistency, and fault tolerance across the network.

Implementation Steps

Step 1: State Updates from Sensors

  • Sensors send state updates (e.g., temperature or energy readings) to a primary node.
  • The primary node appends updates to its replication log.

Step 2: Consensus on State Transitions

  • The primary node proposes state transitions to replicas using a consensus protocol.
  • All nodes agree on the transition order before applying the update.

Step 3: Fault Recovery

  • If a node fails, it replays the replication log to recover the current state.
The diagram illustrates the Fault Recovery Process in distributed state machine replication. When a replica node fails, the system detects the failure and replays replication logs to restore data consistency. If consistency is successfully restored, the node is re-synchronized with the cluster, returning the system to normal operation. If the restoration fails, the issue is logged to the event stream, and manual intervention is triggered. This process ensures the system maintains high availability and reliability even during node failures.

Problem Context:

A smart factory monitors machinery health using sensors for temperature, vibration, and energy consumption. When a machine overheats, alerts trigger actions such as slowing or shutting it down.

Solution:

  • State Update: A sensor sends a “High Temperature Alert” to the primary node.
  • Consensus: Nodes agree on the alert’s sequence and validity.
  • State Synchronization: All nodes apply the state transition, triggering machine shutdown.
  • Fault Recovery: A failed node replays the replication log to update its state.

Practical Considerations & Trade-Offs

  1. Latency: Consensus protocols may introduce delays for real-time state transitions.
  2. Complexity: Implementing protocols like Raft adds development overhead.
  3. Resource Usage: Logging and replaying updates require additional storage and compute resources.

The Distributed State Machine Replication pattern provides a reliable and scalable solution for maintaining consistent states in IIoT systems. In a manufacturing context, it ensures synchronized monitoring and fault tolerance, reducing downtime and optimizing operations. For industries where real-time data integrity is crucial, this pattern is indispensable.

Thank you for being a part of the community

Before you go:

Distributed Systems Design Pattern: Write-Through Cache with Coherence — [Real-Time Sports Data…

The diagram illustrates the Write-Through Cache with Coherence pattern for real-time sports data. When a user request is received for live scores, the update is written synchronously to Cache Node A and the Database (ensuring consistent updates). Cache Node A triggers an update propagation to other cache nodes (Cache Node B and Cache Node C) to maintain cache coherence. Acknowledgments confirm the updates, allowing all nodes to serve the latest data to users with minimal latency. This approach ensures fresh and consistent live sports data across all cache nodes.

In real-time sports data broadcasting systems, ensuring that users receive the latest updates with minimal delay is critical. Whether it’s live scores, player statistics, or game events, millions of users rely on accurate and up-to-date information. The Write-Through Cache with Coherence pattern ensures that the cache remains consistent with the underlying data store, reducing latency while delivering the latest data to users.

The Problem: Data Staleness and Latency in Sports Broadcasting

In a sports data broadcasting system, live updates (such as goals scored, fouls, or match times) are ingested, processed, and sent to millions of end-users. To improve response times, this data is cached across multiple distributed nodes. However, two key challenges arise:

  1. Stale Data: If updates are written only to the database and asynchronously propagated to the cache, there is a risk of stale data being served to end users.
  2. Cache Coherence: Maintaining consistent data across all caches is difficult when multiple nodes are involved in serving live requests.
The diagram illustrates the issue of data staleness and delayed updates in a sports broadcasting system. When a sports fan sends the 1st request, Cache Node A responds with a stale score (1–0) due to pending updates. On the 2nd request, Cache Node B responds with the latest score (2–0) after receiving the latest update propagated from the database. The delay in updating Cache Node A highlights the inconsistency caused by asynchronous update propagation.

Example Problem Scenario:
Consider a live soccer match where Node A receives a “Goal Scored” update and writes it to the database but delays propagating the update to its cache. Node B, which serves a user request, still shows the old score because its cache is stale. This inconsistency degrades the user experience and erodes trust in the system.

Write-Through Cache with Coherence

The Write-Through Cache pattern solves the problem of stale data by writing updates simultaneously to both the cache and the underlying data store. Coupled with a coherence mechanism, the system ensures that all cache nodes remain synchronized.

Here’s how it works:

  1. Write-Through Mechanism:
  • When an update (e.g., “Goal Scored”) is received, it is written to the cache and the database in a single operation.
  • The cache always holds the latest version of the data, eliminating the risk of stale reads.

2. Cache Coherence:

  • A coherence protocol propagates updates to all other cache nodes. This ensures that every node serves consistent data.
  • For example, when Node A updates its cache, it notifies Nodes B and C to invalidate or update their caches.

Implementation Steps [High Level]

Step 1: Data Ingestion

  • Real-time updates (e.g., goals, statistics) are received via an event stream (e.g., Kafka).

Step 2: Write-Through Updates

The diagram illustrates the Write-Through Cache Mechanism for live sports updates. When the Live Sports Feed sends a New Goal Update (2–0), the update is synchronously written to the Database and reflected in Cache Node A. The database confirms the update, and an acknowledgment is sent back to the Live Sports Feed to confirm success. This ensures that the cache and database remain consistent, enabling reliable and up-to-date data for users.
  • Updates are written synchronously to both the cache and the database to ensure immediate consistency.

Step 3: Cache Coherence

The diagram illustrates Cache Coherence Propagation across distributed cache nodes. Cache Node A propagates a Goal Update (2–0) to Cache Node B and Cache Node C. Both nodes acknowledge the update, ensuring all cache nodes remain synchronized. This process guarantees cache coherence, enabling consistent and up-to-date data across the distributed system.
  • The cache nodes propagate the update or invalidation signal to all other nodes, ensuring coherence.

Step 4: Serving Requests

The diagram demonstrates serving fresh live scores to users using synchronized cache nodes. A Sports Fan requests the live score from Cache Node A and Cache Node B. Both nodes respond with the fresh score (2–0), ensuring data consistency and synchronization. Notes highlight that the data is up-to-date in Cache Node A and propagated successfully to Cache Node B, showcasing efficient cache coherence.
  • User requests are served from the cache, which now holds the latest data.

Advantages of Write-Through Cache with Coherence

  1. Data Consistency:
    Updates are written to the cache and database simultaneously, ensuring consistent data availability.
  2. Low Latency:
    Users receive live updates directly from the cache without waiting for the database query.
  3. Cache Coherence:
    Updates are propagated to all cache nodes, ensuring that every node serves the latest data.
  4. Scalability:
    The pattern scales well with distributed caches, making it ideal for systems handling high-frequency updates.

Practical Considerations and Trade-Offs

While the Write-Through Cache with Coherence pattern ensures consistency, there are trade-offs:

  • Latency in Writes: Writing updates to both the cache and database synchronously may slightly increase latency for write operations.
  • Network Overhead: Propagating coherence updates to all nodes incurs additional network costs.
  • Write Amplification: Each write operation results in two updates (cache + database).

In real-time sports broadcasting systems, this pattern ensures that live updates, such as goals or player stats, are consistently visible to all users. For example:

  • When a “Goal Scored” update is received, it is written to the cache and database simultaneously.
  • The update propagates to all cache nodes, ensuring that every user sees the latest score within milliseconds.
  • Fans tracking the match receive accurate and timely updates, enhancing their viewing experience.

In sports broadcasting, where every second counts, this pattern ensures that millions of users receive accurate, up-to-date information without delay. By synchronizing updates across cache nodes and the database, this design guarantees an exceptional user experience for live sports enthusiasts.

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Before you go:

Distributed Systems Design Pattern: Lease-Based Coordination — [Stock Trading Data Consistency Use…

An overview of the Lease-Based Coordination process: The Lease Coordinator manages the lease lifecycle, allowing one node to perform exclusive updates to the stock price data at a time.

The Lease-Based Coordination pattern offers an efficient mechanism to assign temporary control of a resource, such as stock price updates, to a single node. This approach prevents stale data and ensures that traders and algorithms always operate on consistent, real-time information.

The Problem: Ensuring Consistency and Freshness in Real-Time Trading

The diagram illustrates how uncoordinated updates across nodes lead to inconsistent stock prices ($100 at T1 and $95 at T2). The lack of synchronization results in conflicting values being served to the trader.

In a distributed stock trading environment, stock price data is replicated across multiple nodes to achieve high availability and low latency. However, this replication introduces challenges:

  • Stale Data Reads: Nodes might serve outdated price data to clients if updates are delayed or inconsistent across replicas.
  • Write Conflicts: Multiple nodes may attempt to update the same stock price simultaneously, leading to race conditions and inconsistent data.
  • High Availability Requirements: In trading systems, even a millisecond of downtime can lead to significant financial losses, making traditional locking mechanisms unsuitable due to latency overheads.

Example Problem Scenario:
Consider a stock trading platform where Node A and Node B replicate stock price data for high availability. If Node A updates the price of a stock but Node B serves an outdated value to a trader, it may lead to incorrect trades and financial loss. Additionally, simultaneous updates from multiple nodes can create inconsistencies in the price history, causing a loss of trust in the system.

Lease-Based Coordination

The diagram illustrates the lease-based coordination mechanism, where the Lease Coordinator grants a lease to Node A for exclusive updates. Node A notifies Node B of its ownership, ensuring consistent data updates.

The Lease-Based Coordination pattern addresses these challenges by granting temporary ownership (a lease) to a single node, allowing it to perform updates and serve data exclusively for the lease duration. Here’s how it works:

  1. Lease Assignment: A central coordinator assigns a lease to a node, granting it exclusive rights to update and serve a specific resource (e.g., stock prices) for a predefined time period.
  2. Lease Expiry: The lease has a strict expiration time, ensuring that if the node fails or becomes unresponsive, other nodes can take over after the lease expires.
  3. Renewal Mechanism: The node holding the lease must periodically renew it with the coordinator to maintain ownership. If it fails to renew, the lease is reassigned to another node.

This approach ensures that only the node with the active lease can update and serve data, maintaining consistency across the system.

Implementation: Lease-Based Coordination in Stock Trading

The diagram shows the lifecycle of a lease, starting with its assignment to Node A, renewal requests, and potential reassignment to Node B if Node A fails, ensuring consistent stock price updates.

Step 1: Centralized Lease Coordinator

A centralized service acts as the lease coordinator, managing the assignment and renewal of leases. For example, Node A requests a lease to update stock prices, and the coordinator grants it ownership for 5 seconds.

Step 2: Exclusive Updates

While the lease is active, Node A updates the stock price and serves consistent data to traders. Other nodes are restricted from making updates but can still read the data.

Step 3: Lease Renewal

Before the lease expires, Node A sends a renewal request to the coordinator. If Node A is healthy and responsive, the lease is extended. If not, the coordinator reassigns the lease to another node (e.g., Node B).

Step 4: Reassignment on Failure

If Node A fails or becomes unresponsive, the lease expires. The coordinator assigns a new lease to Node B, ensuring uninterrupted updates and data availability.

Practical Considerations and Trade-Offs

While Lease-Based Coordination provides significant benefits, there are trade-offs:

  • Clock Synchronization: Requires accurate clock synchronization between nodes to avoid premature or delayed lease expiry.
  • Latency Overhead: Frequent lease renewals can add slight latency to the system.
  • Single Point of Failure: A centralized lease coordinator introduces a potential bottleneck, though it can be mitigated with replication.

Stackademic 🎓

Thank you for reading until the end. Before you go:

Why Focus Beats Discipline Every Time?

“Success is not about doing everything, but about doing the right things.”

In a world overwhelmed by distractions and opportunities, focus is the superpower that separates the truly successful from the merely busy. Discipline often gets the credit for achievement, but without focus, even the most disciplined effort can lead to burnout and mediocrity.

As Stephen Covey aptly writes in The 7 Habits of Highly Effective People: “The key is in not spending time, but in investing it.”

The true measure of progress isn’t how much we do but how intentionally we direct our energy. Let’s explore why focus is the foundation of excellence and how you can cultivate it to achieve your long-term goals.

Why Focus Matters More Than Ever

Focus is the ability to prioritize what matters most while filtering out distractions. It’s a skill that requires both clarity and courage. In Essentialism, Greg McKeown emphasizes: “If you don’t prioritize your life, someone else will.”

Today, we live in an era of endless opportunities. Every notification, email, or shiny new project pulls us in different directions. This is why focus isn’t just about knowing what to do — it’s about knowing what not to do. Focus requires the bravery to say “no” to good opportunities so you can pursue great ones.

Excellence Takes Time

Greatness isn’t built overnight. Whether it’s mastering a craft, building a business, or nurturing meaningful relationships, achieving excellence takes time. As Malcolm Gladwell popularized in Outliers, it takes roughly 10,000 hours of deliberate practice — or about a decade — to master any skill.

This timeline isn’t a limitation; it’s a guide. The question isn’t if you’ll invest time but how. Trying to excel in too many areas simultaneously dilutes your effort. Instead, focus deeply on one priority at a time. Progress isn’t about doing everything — it’s about doing the right things with sustained effort.

Principles for Achieving Laser-Sharp Focus

To cultivate focus in a way that aligns with your long-term goals, consider these four principles:

1. Say No More Often

As Steve Jobs famously said: “Focus is about saying no.” Every “yes” takes time and energy away from something more important. Before committing to a new task or opportunity, ask yourself: Does this align with my long-term vision? If the answer is no, let it go.

Saying no isn’t easy, but it’s necessary. In The Subtle Art of Not Giving a F***, Mark Manson reminds us: “The more something matters, the more we must say no to everything else.”

2. Adopt the 10-Year Perspective

When considering new ventures, relationships, or commitments, think long-term. Ask yourself: Will this matter in 10 years? This mindset helps you avoid distractions and focus on what truly matters.

As James Clear writes in Atomic Habits: “You do not rise to the level of your goals. You fall to the level of your systems.” Long-term success requires aligning daily actions with your big-picture vision.

3. Consider Opportunity Costs

Time is your most valuable asset. Tasks that don’t require your unique skills — like household chores or administrative work — can often be delegated or outsourced.

Naval Ravikant, in his wisdom, advises: “Play long-term games with long-term people.” By focusing your time on high-impact activities, you create compounding value over time.

4. Simplify to Amplify

Complexity breeds confusion, while simplicity enables clarity. Block your time into distinct slots for learning, creating, and managing. As Leonardo da Vinci said: “Simplicity is the ultimate sophistication.”

In Deep Work, Cal Newport highlights the importance of creating an environment that supports focused work: “Clarity about what matters provides clarity about what does not.”

Focus isn’t just a productivity hack — it’s a way of life. It’s the tool that allows you to align your actions with your values and build a life of meaning and achievement.

So, ask yourself:

  • What are the areas in your life where you need to focus more?
  • Are you pursuing what’s truly important, or simply reacting to what feels urgent?
  • What steps can you take today to simplify and refocus?

Focus is a practice, not a destination. By committing to clarity, saying no to distractions, and embracing the power of simplicity, you can achieve the extraordinary.

Distributed Systems Design Pattern: Shard Rebalancing — [Telecom Customer Data Distribution Use…

In distributed telecom systems, customer data is often stored across multiple nodes, with each node responsible for handling a subset, or shard, of the total data. When customer traffic spikes or new customers are added, certain nodes may become overloaded, leading to performance degradation. The Shard Rebalancing pattern addresses this challenge by dynamically redistributing data across nodes, ensuring balanced load and optimal access speeds.

The Problem: Uneven Load Distribution in Telecom Data Systems

Illustration of uneven shard distribution across nodes in a telecom system. Node 1 is overloaded with high-traffic shards, while Node 2 remains underutilized. Redistribution of shards can help balance the load.

Telecom providers handle vast amounts of customer data, including call records, billing information, and service plans. This data is typically partitioned across multiple nodes to support scalability and high availability. However, several challenges can arise:

  • Skewed Data Distribution: Certain shards may contain data for high-traffic regions or customers, causing uneven load distribution across nodes.
  • Dynamic Traffic Patterns: Events such as promotional campaigns or network outages can lead to sudden traffic spikes in specific shards, overwhelming the nodes handling them.
  • Scalability Challenges: As the number of customers grows, adding new nodes or redistributing shards becomes necessary to prevent performance bottlenecks.

Example Problem Scenario:
A telecom provider stores customer data by region, with each shard representing a geographical area. During a popular live-streaming event, customers in one region (e.g., a metropolitan city) generate significantly higher traffic, overwhelming the node responsible for that shard. Customers experience delayed responses for call setup, billing inquiries, and plan updates, degrading the overall user experience.

Shard Rebalancing: Dynamically Redistributing Data

Shard Rebalancing process during load redistribution in a telecom system. Node 1 redistributes Shards 1 and 2 to balance load across Node 2 and a newly joined node, Host 3. This ensures consistent performance across the system.

The Shard Rebalancing pattern solves this problem by dynamically redistributing data across nodes to balance load and ensure consistent performance. Here’s how it works:

  1. Monitoring Load: The system continuously monitors load on each node, identifying hotspots where specific shards are under heavy traffic or processing.
  2. Redistribution Logic: When a node exceeds its load threshold, the system redistributes part of its data to less-utilized nodes. This may involve splitting a shard into smaller pieces or migrating entire shards.
  3. Minimal Downtime: Shard rebalancing is performed with minimal disruption to ensure ongoing data access for customers.

Telecom Customer Data During Peak Events

Problem Context:

A large telecom provider offers video-on-demand services alongside traditional voice and data plans. During peak events, such as the live-streaming of a global sports final, traffic spikes in urban regions with dense populations. The node handling the shard for that region becomes overloaded, causing delays in streaming access and service requests.

Shard Rebalancing in Action:

  1. Load Monitoring: The system detects that the shard representing the urban region has reached 90% of its resource capacity.

2. Dynamic Redistribution:

  • The system splits the shard into smaller sub-shards (e.g., splitting based on city districts or user groups).
  • One sub-shard remains on the original node, while the others are migrated to underutilized nodes in the cluster.

3. Seamless Transition: DNS routing updates ensure customer requests are directed to the new nodes without downtime or manual intervention.

4. Balanced Load: The system achieves an even distribution of traffic, reducing response times for all users.

Shard rebalancing in action during a peak traffic event in an urban region. The Load Monitor detects high utilization of Shard 1 at Node 1, prompting shard splitting and migration to Node 2 and a newly added Node 3, ensuring balanced system performance.

Results:

  • Reduced latency for live-streaming customers in the overloaded region.
  • Improved system resilience during future traffic spikes.
  • Efficient utilization of resources across the entire cluster.

Practical Considerations and Trade-Offs

While Shard Rebalancing provides significant benefits, there are challenges to consider:

  • Data Migration Overheads: Redistributing shards involves data movement, which can temporarily increase network usage.
  • Complex Metadata Management: Tracking shard locations and ensuring seamless access requires robust metadata systems.
  • Latency During Rebalancing: Although designed for minimal disruption, some delay may occur during shard redistribution.

The Shard Rebalancing pattern is crucial for maintaining balanced loads and high performance in distributed telecom systems. By dynamically redistributing data across nodes, it ensures efficient resource utilization and provides optimal user experiences, even during unexpected traffic surges.

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