Aleksandr

Senior Java Software Engineer with Concurrency High-Load experience

Name: Aleksandr

Surname: Trubitskiy

Position: Senior Java developer

English level: Upper intermediate (B2+)

Location: Ukraine, Odessa

Registered as a sole proprietor in Ukraine (3rd tax group)

Contacts:

 Mail: [відкрити контакти](див. вище в блоці «контактна інформація»)

 Phone: [відкрити контакти](див. вище в блоці «контактна інформація»)

 Telegram: @star15095

SUMMARY
About me:
Professional IT Specialist with over 15 years of experience in the IT industry.
Highly responsible and motivated in solving complex challenges software
development and aplication design tasks. Extensive expertise in developing
Java applications using Spring MVC, Reactive Spring WebFlux, Qarkus, Vert.x
frameworks. More than 10 years experiance desiging and developing code
for monolith, layered, DDD, hexogonal, multi-tenant, distributed, API-first ,
microservice architechure application design with high-rpc and event-
sourcing design deployed to cloud infostructure, VMs, or k8s cluster.
Proficient in designing and building Java Async and Concurency Hight Load,
High Throughput Low latency Real Time applications , As same as bulding
horizontal scaling distributed High-Performance,High Throughput and Heavy
Compute Engine Producer-Consumer services As same Bulding Reactive Hight
I/O Operations as with event-driven project design.
Proficnt designing REST API, gRPC, GraphQL,WebSocket API, communication.
Experience in end-to-end project implementation, spanning from low level of
infrostructure & networking to application layers with excelent skills of
writing&maintaince extensible, and high-performance application code
optimized for JIT C1/C2/Graal Compiler and JVM Escape Analysis, or GraalVM
native image.
Application performance optimization techniques supporting stability with
monitoring logging and metrics using ELK, Prometheus, Grafana,
AppDynamics, New Relic.
Strong expertise in SQL and database optimization. Hands-on experience with
NoSQL databases, distributed caching, optimistic and pessimistic locking, and
transaction management. Deep understanding of ACID and CAP theorem,
including consistency models and trade-offs in distributed systems.
Familiar with Linux/Unix OS, Docker Build, Docker Images, Registry, Kubernetis
, Linux OS & Bash.
Expertise in designing secure (SSO, OAuth 2.1, JWT) and robust networking
protocols, including TLS 1.3, WireGuard, and IPsec, with full compliance to
OWASP ASVS."
DevOps and Networking skils experience. Bash and Python scripting.
Strong drive to learn and adapt to new technologies in AI ML DL local
LLM.GenAI, AI Platform RAG. OpenApi, Cloude.
 Java development experiance, with strong knowledge of Java Core, Collections
Framework , Data-Oriented and Functional Programming . Deep understanding of
algorithms, data structures, and concurrency for high-performance backend systems.
Proven experience in OOP with SOLID and using Java GoF Design Patterns. Extensive
expertise in solving complex tasks in multithreading async concurent tasks.
Throughout my career, I have contributed to various projects featuring Monolithic,
Micro-services architecture, Big Data Event-Driven Microservice Distributed
architecture projects with SQL and NoSQL DB, Cashes, and kafka deployed to K8s.
Experiance with Real time and low latency applications and Hight load Reactive
processing with hight rps and controlling Backpressure, Batching, . Wide experiance
in implementation AWS, Azure, GCP environments, deploing AWS Lambda, or EC2
instances, or EKS Kubernetes orchestration. Experienced with deploying Kubernetes
cluster from scratch.
 10+ years of experience with DevOps and automation , proficent in
Linux Ubuntu/Centos, Bash and Python scripting experianse deploing
CI/CD with Jenkins pipelines, GitLab Ci-CD, Docker
build/deployment processes, and in-depth knowledge of Cloud
Providers AWS, GCP, Azure, VM-WareVsphere. Proficient in
infrastructure design and skilled in using orchestration tools like
Kubernetes. Automation tasks with Ansible. AWS resource
management using Terraform, or using AWS cloud formation.
 10+ years of experience in network engineering and system
administration background, with a strong understanding of network
protocols and the TCP/IP stack.
, complemented by specialized IT courses CCNA CCNP and
continuous learning. AD/LDAP system design, networking,
Linux/Unix operating systems, and cloud platforms (AWS/GCP).

 University degree at ONAS "Odessa National Academy of Telecommunications" 2004-
2009
 Java development experience

• Java Developer Experience (10+ years) Java Versions: 8, 11, 17, 21, 24, 26,
GraalVM — actively used in production; led migrations across versions,
leveraging new LTS features and post-LTS innovations (Structured Concurrency,
Vector API, Foreign Function & Memory API, Stream Gatherers). Fluent with
patterns predifined object pool, zero copy, ring buffers.

Core Expertise

• Java Core: Deep knowledge of collections, lambdas, streams API , functional interases, API,
records, sealed classes, exception handling and loging.
• Multithreading & Concurrency: Executors, Fork/Join, CompletableFuture, Virtual threads
(Project Loom), StructuredTaskScope (Java 26), synchronized/volatile, locks, JMM (Java
Memory Model), happens-before relationships.
• Memory Model & Fundamentals: Full understanding of JMM, weak/soft/phantom
references, methods inlining JIT tiers (C1/C2).
• Performance & Profiling: Async-profiler, flame graphs, JDK Flight Recorder (JFR), VisualVM,
low-latency optimizations, zero-copy patterns.

High-Performance Concurrency & System Design

Modern Java Core (v21–26)

• Virtual Threads & Structured Concurrency: Expert in scaling I/O-bound applications using
VirtualThreads and StructuredTaskScope for resilient, leak-free task management.

• Low-Level Optimization: Advanced usage of Vector API for SIMD operations and VarHandle
for precise memory ordering and lock-free primitives.

Advanced Multithreading & Synchronization

• Lock-Free & Wait-Free Strategies: Deep knowledge of CAS-based structures, solving the
ABA problem, and utilizing AtomicLong, LongAdder, and AtomicReference for extreme
throughput.

• Sophisticated Locking: Implementing Optimistic Locking with StampedLock to minimize
contention, and handling complex synchronization with Semaphores (Rate Limiters) and
Phasers.

• Heavy Compute: Designing CPU-intensive workloads using Fork/Join Framework with
RecursiveTask for optimal work-stealing efficiency.

Reactive & Async Patterns

• Asynchronous Orchestration: Building complex pipelines using Monads
(CompletableFuture, Promise) and reactive streams with integrated Backpressure (via
ArrayBlockingQueue and custom flow control).
• Reactive and EventLoop Spring

• Pattern Implementation: Practical experience with Producer-Consumer (Buffered),
Flyweight for memory efficiency, and Active Object patterns.

Performance Tuning & Low Latency

• Memory Management: Engineering Zero-Copy data transfers, implementing Predefined
Object Pools, and utilizing Ring Buffers (Disruptor style) to bypass GC pressure.

• Data Structures: Expert-level tuning of ConcurrentHashMap and ConcurrentLinkedQueue
for high-concurrency access.

• GC & JVM Optimization: Fine-tuning ZGC (Generational) and G1 for sub-millisecond pauses
in multi-terabyte heap environments.

• Resilience: Proactive resolution of Deadlocks, Livelocks, and resource starvation in high-
load distributed systems.

Design Patterns & Architecture patterns

• Expert-level proficiency in OOP and Implementing GoF design patterns.
• Expert in SOLID principles, folowing GRASP,DRY, KISS, YAGNI, clean and hexagonal
architecture, DDD, concurrency, distributed systems, performance optimization, and
fault-tolerant system design, anti-pattern identification and elimination
• Extensive experience designing low-latency, real-time systems, leveraging techniques such
as heap-based data structures, zero-copy buffers, object pooling, and ring buffer
architectures
• Proven track record in monolith ↔ microservices transformations, with a pragmatic
approach to evaluating trade-offs,
• Solid experience with event-driven architectures and large-scale data processing pipelines
using technologies like Apache Kafka Streams and Amazon Kinesis
• Experiance integrating Keycloak as SSO with JWT + OAuth2, OpenID Connect , SAML,
LDAP/Active Directory
• Solid experience with services communnication using REST with HATOAS, gRPC, GraphQL
• Deep knowledge of microservices architecture patterns, including experience with:
• API Gateway
• Autoscaling Gorizontaly With K8s HPA
• Backend for Frontend
• Idempotency Key
• Change Data Capture Debezium
• CQRS
• Outbox
• Service Registry and Discovery
• Event Sourcing
• Database per Service
• Dead Letter Topics (DLT)
• Circuit Breaker
 • RateLimiter
• Retry + DLQ (Dead Letter Queue)
• Saga Pattern

Spring Di IoT

• Extensive experience: Spring Boot 3+, Spring Web, Spring Security (JWT/OAuth2/RBAC),
Spring Cloud (Config, Gateway, Eureka, Stream), Spring Data (JPA, MongoDB, Cassandra),
Spring integration,, Actuator, Spring AOP, WebSockets, Spring Retry, Spring Vault,
Swagger/OpenAPI, Spring Kafka, Strems
• Spring WebFlux, Spring Security Reactive, Spring Data(R2DBC, Redis, MongoDB),
Resilience4j ,Micrometer Tracing, OpenTelemetry
• Designed secure, transactional apps with @transactional propagation/isolation levels,

Alternative frameworks

Experience with Quarkus, Vert.x , Micronaut

Testing & Quality

• Proficient in JUnit 5, Mockito, Hamcrest, PowerMock, Testcontainers (LocalStack,
PostgreSQL, Kafka), JaCoCo.
• Quality gates: SonarQube, Checkstyle, integration testing with JMeter/Postman.

Kafka & Messaging experience

• Experiance creating Kafka Producers/Consumers with Java and Python, Kafka Streams,
KSQL , Schema Registry (Avro,Json), ACLs, LDAP winth SASL kerberos auth. Kafka
idempotency, Kafka serialization. Topic Configuration, Partitioning
configuration,Replication Factor, Min In Sync Replica, Ack ,Commits, Kafka Transaction
configuration. Kafka Dead Letter Topics (DLT).
• Experiance with Kafka Cluster configuuration. Experiamce with deployment via Terraform +
Ansible/Packer on AWS EC2 or AWS EKS Statfull Set.

• Relational Databases & Persistence Layer

• RDBMS (MySQL 8, PostgreSQL): Expert in designing highly available and scalable relational
schemas. Proficient in advanced SQL, including window functions, recursive CTEs, and
complex aggregations. Deep understanding of ACID compliance and transaction isolation
levels (Read Committed vs. Repeatable Read) to prevent anomalies in high-concurrency
environments.
• Performance Tuning: Extensive experience in query optimization using EXPLAIN ANALYZE,
index strategy (B-Tree, GIN, BRIN, Composite indexes), and database maintenance. Skilled
in handling VLDB (Very Large Databases) through horizontal and vertical partitioning,
sharding, and read-replica orchestration. Experiance winth Async Synchronous Semi-
synchronous replication
• ORM & Data Access:

Hibernate/JPA: Advanced usage including custom @EntityGraph for N+1 problem
resolution, 2nd-level caching strategies, and managing complex polymorphic associations.

AWS Cloud & Deployment

• Hands-on experience with AWS: EC2, EKS, ECS, Lambda, SQS/SNS/EventBridge/Kinesis,
DynamoDB, RDS, Auro, ElastiCache, Cognito,KMS, IAM, Groups,Policy,Secrets Manager,
VPC, API Gateway, CloudWatch,TGW, PrivateLink, Peering, SecurityGroup, ALB, NLB.
• Deployment: Terraform, AWS CDK, CloudFormation, Helm charts, zero-downtime
deployments.

DevOps & Containerization

• CI/CD: Jenkins pipelines, GitHub Actions, ArgoCD, Blue/Green, Rollaou, Canary
deploymants.
•
• Docker (multi-stage build), Kubernetes (EKS, cluster deployed from scratch with vms GCP
intance, kubctl config with YAML, Helm deploy, experience deploying KubeSphere).

• Relational Databases & Persistence Layer

• RDBMS (MySQL 8, PostgreSQL): Expert in designing highly available and scalable relational
schemas. Proficient in advanced SQL, including window functions, recursive CTEs, and
complex aggregations. Deep understanding of ACID compliance and transaction isolation
levels (Read Committed vs. Repeatable Read) to prevent anomalies in high-concurrency
environments.

• Performance Tuning: Extensive experience in query optimization using EXPLAIN ANALYZE,
index strategy (B-Tree, GIN, BRIN, Composite indexes), and database maintenance. Skilled
in handling VLDB (Very Large Databases) through horizontal and vertical partitioning,
sharding, and read-replica orchestration. Experiance winth Async Synchronous Semi-
synchronous replication

• ORM & Data Access:

• Hibernate/JPA: Advanced usage including custom @EntityGraph for N+1 problem
resolution, 2nd-level caching strategies, and managing complex polymorphic associations.

• Spring JDBC / JOOQ: Preferred for performance-critical path services where fine-grained
control over SQL and batch processing is required to bypass ORM overhead.

NoSQL & Distributed Data Stores

Key-Value & Document:

• Redis: Utilizing as a distributed cache, rate limiter, and for pub/sub messaging, with a focus
on eviction policies and data persistence (RDB/AOF).
• MongoDB & DynamoDB: Designing schema-less and semi-structured data models. Expert in
DynamoDB Single-Table Design to minimize RCU/WCU costs and latency in AWS
environments.

Wide-Column & Graph:

• Cassandra (CQL): Proficient in Query-First Data Modeling, understanding compaction
strategies, and tuning the CAP theorem trade-offs (Consistency vs. Availability) via Tunable
Consistency.

• JanusGraph: Experience in traversing and modeling highly interconnected data (fraud
detection, social graphs) using Gremlin, with optimized indexing backends.

Utilities

• Utilities: Lombok, Jackson, MapStruct, Guava, Apache Commons, Caffeine, Ehcache;
Observability: Micrometer, OpenTelemetry, JFR; Concurrency: CompletableFuture, Virtual
Threads; Fault tolerance: Resilience4j; Distributed systems tools: Redis, Redisson;
Communication: gRPC, Protobuf, WebClient; Testing: JUnit 5, Mockito, Testcontainers.
•
Logging & Observability

• SLF4J/Logback – structured, asynchronous logging with MDC for traceability in distributed
systems.
• ELK / Splunk integration – real-time log aggregation, search, and alerting for production
observability.

Development & Productivity

• IDE: IntelliJ IDEA + plugins – advanced static analysis with SonarLint, Checkstyle, and
productivity plugins like Lombok support.

Linux administration

• Kernel tuning & performance: Optimize sysctl parameters, I/O, memory, and CPU
scheduler for low-latency and high-throughput workloads. Kernel custom build and
deployment
• Resource isolation & containerization: Master cgroups and namespaces for microservices,
Docker, and Kubernetes environments.
• Networking & security: Configure iptables/nftables, network namespaces, and firewall
rules for multi-tenant secure systems.
• Service management & automation: Expert with systemd for unit files, service
orchestration, dependency management, and automated recovery.
• Observability & diagnostics: Use procfs, perf, strace, iostat, netstat to analyze kernel,
network, and application performance.
• OS-level reliability & scalability: Build robust, production-grade Linux environments for
distributed systems and microservices.

AI Machine Learning and Deep Learning experience with own pet project
 • Machine Learning Experiance (Independent / Non-Commercial Projects) with hands-on
experience building end-to-end ML systems using Python and core libraries such as scikit-
learn, NumPy, pandas, PyTorch, and TensorFlow. Applied a wide range of supervised and
unsupervised algorithms including Linear/Logistic Regression, Random Forest, Gradient
Boosting (XGBoost, LightGBM), Support Vector Machines (SVM), k-NN, and clustering
methods (k-means, DBSCAN), along with dimensionality reduction techniques like PCA.
Experienced in model evaluation, feature engineering, and hyperparameter tuning through
self-driven projects and experimentation.

• Designed and implemented ML pipelines independently, including data preprocessing,
training, validation, and inference stages. Built REST APIs using FastAPI, containerized
applications with Docker, and explored experiment tracking with MLflow in a non-
production environment. Worked with deep learning architectures (CNN, RNN, LSTM,
Transformers) using PyTorch and HuggingFace Transformers for NLP and computer vision
tasks as part of personal and research-oriented projects.

• Developed Retrieval-Augmented Generation (RAG) systems by integrating LLMs with vector
databases (FAISS, Chroma) and embedding models for semantic search and question
answering. Gained hands-on experience with local LLMs (such as LLaMA, Mistral, and other
open-source models) using tools like HuggingFace, Ollama, and LangChain, focusing on
standalone applications and experimental setups. Built intelligent assistants and
knowledge-based systems purely for educational and non-commercial purposes.

Networking & Cloud experiance

• Routing & Switching protocols: Deep knowledge of BGP, OSPF, QoS, MPLS; proven ability
to design and troubleshoot complex enterprise networks.
• Cloud networking: Hands-on with VPC, PrivateLink, Transit Gateway (TGW), Security
Groups for AWS and hybrid-cloud architectures.
• Certifications: CCNA/CCNP-level understanding applied to cloud and on-prem networking
scenarios.
• High-performance integration: Aligns JVM-based applications and microservices with
network stack and OS tuning for optimal throughput and low latency.

Python development using NumPy, Pandas, Scikit-learn, PyTorch, TensorFlow/Keras,
Hugging Face Transformers, Datasets, Tokenizers, LangChain, LlamaIndex, FAISS/Chroma,
FastAPI, Uvicorn, MLflow, Weights & Biases, Ray.

PROFESSIONAL EXPERIENCE

Proxy seller, february 2025 – current time
Company and duration
Position Senior Java Software engineering
Project
Resident Forty Proxy hifgt load low latency real time application
 Proxy server aplication is high load low latency Java real time application
Developed with Java 26, Quarkus / Vert.x 5, Netty, SBE , H2 db, Redis GraalVM
Project Loom, HotSpot, VarHadle,Vavr, Project Panama, VectorApi,

High-Performance & Messaging instruments
1. io.vertx:vertx-io_uring-incubator: Implements a high-performance transport
Technologies for Eclipse Vert.x using the Linux kernel's io_uring interface. It provides
asynchronous, non-blocking I/O operations with reduced overhead compared
to traditional epoll/select.
2. com.lmax:disruptor: A high-performance inter-thread messaging library. It
implements a lock-free, concurrent ring buffer data structure designed for
ultra-low latency applications by avoiding locks and minimizing cache misses.
3. org.agrona:agrona: Provides a library of high-performance data structures and
utility methods for Java. It implements thread-safe direct and atomic buffers
(on and off-heap), lock-less queues, and primitive collections (maps/sets) that
avoid boxing.
4. uk.co.real-logic:sbe-tool: A tool for Simple Binary Encoding (SBE). It implement
an OSI layer 6 presentation for encoding and decoding binary messages,
specifically designed for low-latency financial applications (FIX SBE standard).
5.
High-Performance Serialization & Data Formats instruments
6. com.google.code.gson: A Java library that implements JSON serialization and
deserialization. it can convert Java Objects into JSON representation and vice
versa.
7. org.infinispan.protostream:protostream: A serialization library based on the
Protocol Buffers (Protobuf) format. It implements efficient marshalling of Java
objects into binary format for the Infinispan platform or standalone use.
8. org.tukaani:xz: Implements Java support for the XZ data compression format,
based on the LZMA2 algorithm. It provides high compression ratios for files and
streams.
9. org.codehaus.plexus:plexus-archiver: A component of the Plexus container tha
implements support for creating and extracting various archive formats (ZIP,
JAR, TAR, GZIP, etc.).
High-Performance Storage & System Tools instruments
10. org.rocksdb:rocksdbjni: Provides Java Native Interface (JNI) bindings for
RocksDB, an embeddable persistent key-value store for fast storage. It
implements a high-performance database engine optimized for flash and RAM
storage.
11. com.github.oshi:oshi-core: A free native operating system and hardware
information library (Operating System and Hardware Information). It
implements cross-platform access to system metrics like CPU, memory, disks,
and network usage without requiring additional native libraries.
12. com.maxmind.geoip2:geoip: Implements an API for GeoIP2 and GeoLite2
database lookups. It provides geographical information (country, city,
coordinates) associated with IP addresses.
13.
High-Performance Networking & Security instruments
14. org.bouncycastle:bcprov: A lightweight cryptography API. It implements a wide
range of cryptographic algorithms and provides a JCE (Java Cryptography
Extension) provider.
15. io.vertx:vertx-web: A toolkit for building Web applications on top of Vert.x
Core. It implements routing, auth, session management, and template support
for reactive web servers.
16. io.vertx:vertx-web-client: An asynchronous HTTP and HTTP/2 client. It
 implements a high-level API for interacting with web services and APIs in a non
blocking manner.
Utilities
17. com.google.guava:guava: A comprehensive set of core Java libraries from
Google. It implements collections, caching, primitives support, concurrency
libraries, common annotations, and string processing utilities.
18. in.jlibs:jlibs-core: A collection of general-purpose utility classes for Java. It
typically implements enhancements for XML processing, i18n, and
miscellaneous helper methods.

Developing and implementing new features to proxy server
aplication,
• improving overall session load capacity memmory consumtion and
Responsibilities latency jitter for operations,
• Project stack - Java 26, Quarkus / Vert.x 5, Netty, SBE , H2 db, Redis
GraalVM , Project Loom, HotSpot, VarHadle,Vavr, Project
Panama,VectorApi,

Project Designed with Hight Load, High Throughput Low latency design ,

• Connection processing with Async, Reactive approach using
VirtualThreads,
• Heavy Service tasks And Event Loop processed with PlatformThreads
with ForkJoin Recursive for havy CPU,
• Client Connections Logic Implemented with Structured Concurrency,
Scoped Values,
• Some logic in Verticle logic basic calls with using default
• Pattern -callbacks monades with Feature, Promise,
CompletableFeature,
• Shared Service Resoces Optimistic locks with StampedLock,
AtomicInteger, LongAddr, AtomicRefaranse,
• LockFree Service Logic - Vector API ,
• Echanhe resources between tasks
• Cahhed Client configBalancer ConcurrentHashMap,
• Batched Producer Consumer Logic - ConcurrentLinkedQueue,
Semaphores used for ratelimiter,
• Producer& Consumer buffered Backpressure with
ArrayBlockingQueue.
• Lock Free usage of Perfomance tuning with using of heap
collections. predifined object pool,
• zero copy,
• ring buffers.
• GC G1, ZGC optimization


 Global Logic (Lviv, Ukraine), 2024 – 2025 february
Company and duration
Position Senior Java Software Engineer
Project
Label logic AI – ML image and video labeling service
 Main back-end application is developed using: Java 17, Spring 5, Spring boot
2, Spring Boot Starters: starter-web, starter-security, starter-data-jpa,
starter-validation, starter-actuator, starter-test, gcp-starter-storage,
starter-data-redis,-starter-aop and others.
 Testing libs: Junit5, Mockito.WireMock Test-containers
 Gitlab as repository.
Technologies
 GCP Cloud file storage usage.
 Application uses Redis cache.
 Libs usage: Lombok lib, Model-mapper lib, Commons-io lib, Spring-retry lib.
 DB: MYSQL5
 Transaction support
 K8S KubeSphere cluster is installed on GCP VMs
 Current micro-services in k8s: java-app,python-ai-ml-app, Redis, MySQL-db,
Jenkins, consul
 CI-CD is designed with Jenkins pipeline with deploy to K8S.
I'm proud of our accomplishments:
• Application development
• Introducing new features
Responsibilities • Working on micro-services design implementation
• Code refactoring
• Bug-Fixing,
• Unit and integration test coverage
• Took part in project architecture design.
• Infrastructure and CI-CD setup

“Global Logic” (Lviv, Ukraine), 2023 – 2024 (2 years) (GIG CONTRACTOR)
Company and duration
Position Senior Java software engineer
Project
SIMA – visual data platform: management of pipelines for video streams processing
Technologies  Java 11, Spring 5, Spring MVC, Spring boot 2, Spring Cloud Config. AWS SDK.
 AWS Services used in project: Lambda, S3, SQS, Kinesis, EventBrige, ECS,
Cognito, DynamoDB as DB per service, Amason RDS
 Micro-service project architecture with patterns: API Gateway, Circuit
Breaker, Client-Side UI Composition Pattern, Health checks, Distributed
Tracing id, Database per service, CQRS, SAGA
 Testing: Junit5, Mockito, Localstack.
 CI-CD: Maven, Jenkins
 Linux bash scripting.
 Hands on with AWS services. And AWS SDK
 AWS CDK configs for deployment
 I'm proud of our accomplishments:
• Project design and imrovment
• During my work 3 new micro-services were implemented
UserAdmin Service integrated with AWS Cognito and aws IAM and UI for
Responsibilities user and group management…