SQS Is More Than a Message Array: Visibility Timeouts and DLQ Redrive
How DevCloud's SQS manages message lifecycles with visibility timeouts, receive counts, and receipt handles, plus DLQ moves, redrive, and FIFO deduplication.
DEVLOG IN THE SKY
Notes from building software.
I’m Sung-Kyu Yoo, a backend engineer working on search and platforms. I write about system design, operations, and the tools I build.
Latest posts
All posts →Rewriting Search Results Safely: Unicode Masking and Resource Limits in ACOR
How ACOR's Scan, MaskText, and ReplaceText keep original byte offsets after case folding, resolve overlapping matches, and enforce result and work limits.
Interpreting DynamoDB Expressions: From Tokenization to Conditional Writes
How DevCloud evaluates DynamoDB filter and condition expressions itself: tokenizing, name and value substitution, recursive descent parsing, and type-aware comparison.
Fixing Metrics That Update Only When Status Is Called: Prometheus Collection in ACOR V3
Why ACOR V3 metrics only updated when the status API was called, and how a Prometheus Collector now reads state at scrape time for both HTTP and gRPC.
Fast GETs, Slow Server: Measuring fsync and Raft Queues in KVS
Measuring KVS by function call, RESP round trip, and 200-connection load to explain how a 3.75 ms durable write becomes 758 ms latency and how Raft queues affect GETs.
The Cost of Saying v1: Enforcing Compatibility Promises in Three Go Projects
Taking ACOR, KVS, and DevCloud to v1: retracting ghost versions and using CI to check public API lists, data formats, and config compatibility.