Topic
concurrency
7 articles across 6 sub-topics
Sub-topic
2 articles
Dirty Write Explained: When Uncommitted Data Gets Overwritten
TLDR: A dirty write occurs when Transaction B overwrites data that Transaction A has written but not yet committed. The result is not a rollback or an error — it is silently inconsistent committed data: one table reflects Transaction B's intent, anot...
Lost Update Explained: When Two Writes Become One
TLDR: A lost update occurs when two concurrent read-modify-write transactions both read the same committed value, both compute a new value from it, and both write back — with the second write silently discarding the first. No error is raised. Both tr...
Sub-topic
1 article
Async Python: asyncio, Coroutines, and Event Loops Without the Confusion
📖 The 500-Second Problem: What Cooperative Multitasking Actually Fixes Suppose your monitoring pipeline checks the health endpoint of 1,000 internal microservices. Each HTTP call takes about 500 milliseconds — network round-trip, DNS, TLS handshake,...
Sub-topic
1 article
Compare-and-Swap and Optimistic Locking: How Every Database Implements It
TLDR: Compare-and-Swap (CAS) is the CPU-level atomic instruction that makes lock-free concurrency possible. Optimistic locking builds on it at the database layer: read freely, compute locally, write only if the record has not changed. Every major dat...
Sub-topic
1 article
Adapting to Virtual Threads for Spring Developers
TLDR: Platform threads (one OS thread per request) max out at a few hundred concurrent I/O-bound requests. Virtual threads (JDK 21+) allow millions — with zero I/O-blocking cost. Spring Boot 3.2 enables them with a single property. Avoid synchronized...
Sub-topic
1 article
LLD for Movie Booking System: Designing BookMyShow
TLDR TLDR: A Movie Booking System (like BookMyShow) is an inventory management problem with an expiry: seats expire when the show starts. The core engineering challenge is preventing double-booking under concurrent user load with a 3-state seat mode...
Sub-topic
1 article
Types of Locks Explained: Optimistic vs. Pessimistic Locking
TLDR: Pessimistic locking locks the record before editing — safe but slower under low contention. Optimistic locking checks for changes before saving using a version number — fast but can fail and require retry under high contention. Choosing correct...