Tutorials ADO.NET Core Tutorial
Deadlock Handling — Complete Guide
Deadlock Handling — Complete Guide: free step-by-step lesson with examples, common mistakes, and interview tips — part of ADO.NET Core Tutorial on Toolliyo Academy.
On this page
ADO.NET Core Tutorial · Lesson 34 of 100
Deadlock Handling
Foundations ✓ → SQL & safety → Production → Projects
SQL & safety · 2 — Procs, tx, performance · ~6 min · Module 4: Transactions and Error Handling
What is this?
Deadlocks happen when sessions block each other; SQL picks a victim (1205). Retry the victim safely.
Why should you care?
ShopNest concurrent stock updates deadlock without ordered locking.
See it live — copy this example
Use a .NET console or API project with SQL Server LocalDB. Run dotnet run after pasting.
for (var attempt = 1; attempt <= 3; attempt++)
{
try { await ReserveAsync(ct); break; }
catch (SqlException ex) when (ex.Number == 1205 && attempt < 3)
{ await Task.Delay(50 * attempt, ct); }
}What happened?
- Detect 1205.
- Retry with backoff.
- Prevent by consistent lock order and short transactions.
Practice next
- Catch 1205.
- Retry 3 times.
- Order updates by Sku ASC.
- Log attempt count.
- Fail after 3 with clear error.
Remember
1205 = deadlock victim. Retry with backoff. Prevent with ordering.
ShopNest deadlock retry
Reserve retries on 1205.
Outcome: Users succeed after brief wait.
Interview prep for this lesson
Practice these questions aloud after reading—each links to a full structured answer.
Sign in to ask a question or upvote helpful answers.
No questions yet — be the first to ask!
