Database Deadlock in Concurrent Updates
Application encounters deadlock errors intermittently when multiple users perform operations simultaneously. Specific sequences of operations cause deadlock: Thread A waits for lock held by Thread B, which waits for lock held by Thread A. Application must retry deadlocked operations.
Deadlocks are hard to reproduce but fail under load testing or in production.
Error Messages You Might See
Common Causes
- Transactions acquire locks in different order (A locks table1 then table2, B locks table2 then table1)
- Long-running transactions holding locks too long
- Missing indexes causing full table scans and excessive row locks
- Row-level locks held while waiting for other operations
- No deadlock retry logic in application
How to Fix It
Always acquire locks in same order across application. Use consistent transaction isolation level. Keep transactions short. Add indexes to reduce lock contention. Implement deadlock retry: catch deadlock exception, wait briefly, retry. Check database: SHOW PROCESSLIST shows locks held. Configure deadlock victim: database kills one transaction to resolve.
Real developers can help you.
Omar Faruk
As a Product Engineer at Klasio, I contributed to end-to-end product development, focusing on scalability, performance, and user experience.
My work spanned building and refining core features, developing dynamic website templates, integrating secure and reliable payment gateways, and optimizing the overall system architecture.
I played a key role in creating a scalable and maintainable platform to support educators and learners globally.
I'm enthusiastic about embracing new challenges and making meaningful contributions.
Pratik
SWE with 15+ years of experience building and maintaining web apps and extensive BE infrastructure
Jaime Orts-Caroff
I'm a Senior Android developer, open to work in various fields
Jared Hasson
Full time lead founding dev at a cyber security saas startup, with 10 yoe and a bachelor's in CS. Building & debugging software products is what I've spent my time on for forever
Rudra Bhikadiya
I build and fix web apps across Next.js, Node.js, and DBs.
Comfortable jumping into messy code, broken APIs, and mysterious bugs.
If your project works in theory but not in reality, I help close that gap.
Kingsley Omage
Fullstack software engineer passionate about AI Agents, blockchain, LLMs.
BurnHavoc
Been around fixing other peoples code for 20 years.
hanson1014
Full-stack developer experienced in fixing and deploying AI-generated apps from Lovable, Bolt.new, Cursor, and Replit. I specialize in debugging Supabase integration issues (auth flows, RLS policies, database connections), fixing broken deployments, resolving routing/blank screen problems, and cleaning up messy React/Vite codebases. I also build production apps with the Claude API and have shipped a Mac desktop dev tool (Nexterm from scratch. Based in Hong Kong, fast turnaround.
Sage Fulcher
Hey I'm Sage! Im a Boston area software engineer who grew up in South Florida. Ive worked at a ton of cool places like a telehealth kidney care startup that took part in a billion dollar merger (Cricket health/Interwell health), a boutique design agency where I got to work on a ton of exciting startups including a photography education app, a collegiate Esports league and more (Philosophie), a data analytics as a service startup in Cambridge (MA) as well as at Phillips and MIT Lincoln Lab where I designed and developed novel network security visualizations and analytics. I've been writing code and furiously devoted to using computers to make people’s lives easier for about 17 years. My degree is in making computers make pretty lights and sounds. Outside of work I love hip hop, the Celtics, professional wrestling, magic the gathering, photography, drumming, and guitars (both making and playing them)
zipking
I am a technologist and product builder dedicated to creating high-impact solutions at the intersection of AI and specialized markets. Currently, I am focused on PropScan (EstateGuard), an AI-driven SaaS platform tailored for the Japanese real estate industry, and exploring the potential of Archify.
As an INFJ-T, I approach development with a "systems-thinking" mindset—balancing technical precision with a deep understanding of user needs. I particularly enjoy the challenge of architecting Vertical AI SaaS and optimizing Small Language Models (SLMs) to solve specific, real-world business problems. Whether I'm in a CTO-level leadership role or hands-on with the code, I thrive on building tools that turn complex data into actionable value.
You don't need to be technical. Just describe what's wrong and a verified developer will handle the rest.
Get HelpFrequently Asked Questions
How to prevent deadlocks?
Always acquire locks in same order. If A acquires table1 then table2, B must too (never table2 then table1).
How to detect deadlock cause?
Enable deadlock logging: innodb_print_all_deadlocks = ON (MySQL). Logs show which queries caused it and lock order.
Should deadlocks be retried?
Yes. Deadlocks are normal under load. Catch DeadlockException, wait briefly (exponential backoff), retry. Usually succeeds on second try.