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--- skills:interview [2026/06/15 10:02] – phong2018
+++ skills:interview [2026/06/15 10:07] (current) – [Transactions] phong2018
@@ Line 260: / Line 260: @@
 . What are deadlocks?
+<code>
+- Deadlock: A situation where two or more transactions hold locks and wait for each other indefinitely.
+- How it occurs: Transactions access the same resources in different orders. Long-running transactions hold locks too long. Missing indexes cause unnecessary locking.
+- How to detect it: The database detects deadlocks automatically. MySQL returns: ERROR 1213: Deadlock found when trying to get lock. Investigate with SHOW ENGINE INNODB STATUS.
+- How to prevent it: Keep transactions short. Always access tables/rows in a consistent order. Add proper indexes. Avoid large batch operations in a single transaction.
+- How to recover: The database rolls back one transaction automatically. Catch the error in the application and retry the transaction with backoff.
+</code>
 ==== Large Scale Databases ====
@@ Line 492: / Line 498: @@
 . What backend technology trends are you currently following?
-====== More detail versions ======
-====== Senior PHP (Laravel/Symfony) & Golang Backend Interview Questions ======
-===== PHP Fundamentals =====
-. What are PSR standards (PSR-1, PSR-12, PSR-4) and why do they matter for team consistency?
-. What new features in PHP 8.x (attributes, enums, fibers, named arguments, match expression, nullsafe operator) have you used in production?
-. How does Composer autoloading work, and what is the difference between PSR-4, PSR-0, classmap, and files autoloading?
-. What is the difference between interface, abstract class, and trait — and when should you choose each?
-. What are PHP attributes (#[Attribute]) and when would you use them instead of docblock annotations?
-. How does PHP-FPM work, and how does it manage worker processes to handle concurrent requests?
-. How does OPCache improve performance, and what happens when a file changes after it has been cached?
-. Explain the lifecycle of an HTTP request in PHP from the moment it hits the server to the response being sent back.
-. How does memory management work in PHP — how is memory allocated per request and what causes memory leaks?
-. Can PHP handle concurrency, and what approaches can be used (async, parallel, process-based)?
-. How would you implement concurrent API calls in PHP (e.g. calling three external APIs in parallel)?
-. What are Fibers in PHP 8.1 and how do they differ from goroutines or threads?
-. What is Swoole or RoadRunner and how do they differ from the traditional PHP-FPM request model?
-. What do the three numbers in Semantic Versioning (MAJOR.MINOR.PATCH) mean, and when should each be incremented?
-====== System Design Interview Questions (Drawing Required) ======
+====== System Design Interview Questions ======
 ===== Interview Framework =====
@@ Line 754: / Line 740: @@
+====== More detail versions ======
+====== Senior PHP (Laravel/Symfony) & Golang Backend Interview Questions ======
+===== PHP Fundamentals =====
+. What are PSR standards (PSR-1, PSR-12, PSR-4) and why do they matter for team consistency?
+. What new features in PHP 8.x (attributes, enums, fibers, named arguments, match expression, nullsafe operator) have you used in production?
+. How does Composer autoloading work, and what is the difference between PSR-4, PSR-0, classmap, and files autoloading?
+. What is the difference between interface, abstract class, and trait — and when should you choose each?
+. What are PHP attributes (#[Attribute]) and when would you use them instead of docblock annotations?
+. How does PHP-FPM work, and how does it manage worker processes to handle concurrent requests?
+. How does OPCache improve performance, and what happens when a file changes after it has been cached?
+. Explain the lifecycle of an HTTP request in PHP from the moment it hits the server to the response being sent back.
+. How does memory management work in PHP — how is memory allocated per request and what causes memory leaks?
+. Can PHP handle concurrency, and what approaches can be used (async, parallel, process-based)?
+. How would you implement concurrent API calls in PHP (e.g. calling three external APIs in parallel)?
+. What are Fibers in PHP 8.1 and how do they differ from goroutines or threads?
+. What is Swoole or RoadRunner and how do they differ from the traditional PHP-FPM request model?
+. What do the three numbers in Semantic Versioning (MAJOR.MINOR.PATCH) mean, and when should each be incremented?
 ===== Laravel & Symfony =====