Knuth Geek Art Tribute

Geek Art tribute

Knuth Check 2025

 I got a lost 2024 check in 2025 :)

Usually my last name has a typo, so I may send a check to Don XD

Troubleshooting Java, Second Edition

Technical Reviewer:

Troubleshooting Java, Second Edition

Laurențiu Spilcă

MEAP began December 2024
Publication in Early 2026 (estimated)
ISBN 9781633435575
425 pages (estimated)  

 

 

A book where the art of troubleshooting is summarized into best practices and clearly explains what happens under the hood of the JVM is always welcome.

"Java Troubleshooting, 2nd Edition" delivers exactly that, offering a practical and straightforward guide for solving complex issues in Java applications.

Memory & Heap: Having a heap memory leak is sometimes a hard task to diagnose; however, Chapter 11 explains in detail how to detect, analyze, and fix it step by step.

Profiling & Performance: It shows how to find real bottlenecks using tools like JProfiler, VisualVM, and Java Flight Recorder, moving from guesswork to data-driven decisions.

Threads & Concurrency: It describes how to interpret thread dumps, identify deadlocks, and understand thread behavior in production systems.

Transactions & Consistency: Last but not least, data transactions and consistency are the cornerstone of a well-designed application. The book provides details, tips and tricks, and clear explanations that are always helpful for maintaining integrity and stable behavior.

AI-Assisted Troubleshooting: This new edition also introduces AI-based stacktrace analysis, making life easier for developers. It not only highlights how AI can speed up diagnosis but also recommends how to use these new trends responsibly—ensuring AI remains a helpful tool rather than becoming yet another problem to solve.

 

Happy $1^6 3^4 5^2 7^0$

A curious progression of factors that can also be premultiplied by $(-1)^8$ and written $\prod_{k=0}^4 (2k-1)^{8-2k}$. (Others write $\bigl(\sum_{k=0}^9 k\bigr)^2$, or $\sum_{k=0}^9 k^3$.)

 
From: https://www-cs-faculty.stanford.edu/~knuth/news25.html

Cacofonía

Del gr. κακοφωνία kakophōnía.

1. f. Disonancia que resulta de la inarmónica combinación de los elementos acústicos de la palabra.

   Sin.:

   • disonancia, discordancia.

   Ant.:

   • eufonía.
     

Se llama cacofonía a la disonancia que produce la combinación inarmónica de sonidos en una frase o palabra. La palabra, como tal, proviene del griego κακοφωνία (kakophonía), que se compone de las raíces κακός (kakós), que significa ‘malo’ o ‘desagradable’, y φωνή (phoné) que significa ‘sonido’. 

La cacofonía puede producirse como consecuencia de la repetición innecesaria, exagerada o cercana de un sonido en una misma frase. Así, ejemplos de cacofonías podrían ser:

• Él dijo que va a bajar abajo.

 

Potrzebie

Primera publicacion de Donald Knuth

Julia Quick Syntax Reference , 2nd edition

Technical Reviewer:

Julia Quick Syntax Reference - A Pocket Guide for Data Science Programming

2025

Author: Lobianco, Antonello 

https://link.springer.com/book/10.1007/979-8-8688-0965-1

https://github.com/Apress/Julia-Quick-Syntax-Reference-2nd-ed

Magical Haskell

Technical Review:

Upcoming book from Apress Called Magical-Haskell

https://github.com/Apress/Magical-Haskell

https://link.springer.com/book/9798868812811

former: https://leanpub.com/magicalhaskell/read

Kafka 101

 

What is Kafka?

Apache Kafka is an open-source distributed event streaming platform used by thousands of companies for high-performance data pipelines, streaming analytics, data integration, and mission-critical applications. (kafka.apache.org)

•High throughput

•Scalable

•Permanent storage

•High availability

lIn a Synchronous system, a service makes a request, and that thread/process must wait until it receives a response. While this flow is simpler to code (a straightforward structure) it may introduce delays and may create a bottleneck.

lIn contrast, Asynchronous processing, as explained in the EDA (Event-Driven Architecture) presentation by Fusse, allows events to be processed without waiting for an immediate response. Messaging is a common way to implement loose coupling, as messages are sent asynchronously, allowing services to continue working and receive responses later.

lBy using loosely coupled services, we can achieve a scalable architecture without blocking the system while waiting for responses.

CoConsumer Offsets:

o•Offsets: are used as indexes in the log that the consumer sends to the broker.

Kafka tracks the last processed message for each consumer group in a topic using an internal topic called __consumer_offsets.

lIn a monolithic architecture, all components are packaged together as a single code/entity and communicate by calling functions/methods inside of the runtime execution.

lIn a microservice architecture, services communicate (over the network) with each other through APIs or Messaging Systems (asynchronous).

lIn distributed systems the communications brings more challenges than in a monolith architecture. However, brings some benefits which are related to scalable, fault tolerant applications.

Apache Kafka is a scalable, fault-tolerant, publish-subscribe, streaming messaging system widely used for communication and integration in distributed architectures.

lKafka operates with the following core components:

lMessage: The unit of data within Kafka is called a message, event or record.

lBroker: manages data persistence and replication across nodes in a Kafka cluster.

lCluster: is composed of multiple brokers

lProducer: generates messages and sends them to specific Kafka topics.

lConsumer: reads messages from topics.

Consumer Groups: enable multiple consumers to process data collaboratively, enhancing scalability and fault tolerance. One consumer from a Group read several partitions, but a partition can have only one consumer from a consumer group.

Topics: abstract concept where messages are dispatched, which are divided into partitions to distribute load.

Partitions & Replication:

•each topic can have multiple partitions, spread across different brokers.

•partitions can be replicated for fault tolerance, and each has a designated leader responsible for writes, while replicas handle failover.

•partitions are atomic/indivisible.

•total number of replicas <= number of brokers, as exceeding this will cause an InvalidReplicationFactorException.

Serialization: converts data into binary format for efficient transmission and storage, supporting both native and custom serialization.

 

Security Layers in Kafka    Kafka provides robust security options, including:

•Encryption: SSL/TLS is used for secure communication between clients and brokers, as well as between brokers.

•Authentication: Supports various SASL mechanisms, including OAuth 2, Kerberos, and LDAP, for flexible and secure access control.

•Access Control: Kafka implements Access Control Lists (ACLs) and offers Role-Based Access Control (RBAC) for managing permissions.

Design Patterns & Anti-Patterns    Mentioned in previous presentations, some key patterns include to be used with Kafka:

•CQRS (Command and Query Responsibility Segregation): Separates read and write operations to enhance performance and scalability.

•Event Sourcing: Logs all changes as events to ensure an auditable and re-constructable history of the system's state.   

Performance Considerations

•Compression Trade-offs: Compressing data within Kafka can reduce storage requirements, but it also impacts performance. Brokers and consumers expend resources on data compression and decompression, which can lower both Kafka's throughput and latency.

•Fine tuning Stream Caching and Buffering: Kafka Streams uses caching to reduce the load on state stores and improve processing

•OS Page Cache: Kafka optimizes performance by leveraging the operating system's page cache (by avoiding caching in the JVM heap, the brokers can help prevent some of the issues that large heaps may have (for example, long or frequent garbage collection pauses)

•Message size: it is preferred smaller size than large size

•Among others…

•There is no silver bullet (one-size-fits-all) solution!

Schema Registry

•Centralized repository for managing and validating data structure versus schemas and serialization to ensure data consistency and compatibility.

 

 

Paráfrasis

paráfrasis

Del lat. paraphrăsis, y este del gr. παράφρασις paráphrasis.

1. f. Explicación o interpretación amplificativa de un texto para ilustrarlo o hacerlo más claro o inteligible.

La paráfrasis consiste en decir con palabras más sencillas y con menos palabras técnicas las ideas propias obtenidas de un texto predeterminado.