OPEN-SOURCE RESEARCH / FIELD GUIDE 001
A map through
unfamiliar code.
Find your way into a codebase. Follow real issues, form hypotheses, and learn by investigating.
THERQEDITIONNO. 001
GITHUB / PUBLIC REPOS
N.
STARS143,260
OPEN ISSUES3,674
LANGUAGEJavaScript
DEFAULT BRANCHcanary
YOUR INVESTIGATION
Questline
MISSIONS / 3INDEX
QUEST / 01 OF 3Advanced
PERFORMANCE INVESTIGATION
The cache that held the door
Investigate why image-cache hits can wait for a full disk-LRU scan after the server starts.
01 WHY THIS MATTERS
A persisted cache containing thousands of files can turn an otherwise fast cache hit into a long request stall. This quest explores the trade-offs between startup work and serving requests quickly.
02 THE INVESTIGATION
- 01Read the issue and follow its reproduction link to understand the reported behaviour.
- 02Locate the server-side image-cache and disk-LRU initialization code.
- 03Trace the startup sequence and determine when a cache hit must wait for the scan.
- 04Sketch an alternative that defers or reduces the blocking work.
04 WHAT SUCCESS LOOKS LIKE
- Identify the code responsible for the disk-cache scan.
- Explain why the scan delays cache hits.
- Describe a test that would measure whether a proposed change improves startup latency.
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PRIMARY SOURCE / ISSUE #100179next/image: every cache HIT waits for the full disk-LRU scan after server start
OPEN ISSUE ↗05 CHECK YOUR UNDERSTANDING
FIELD TEST / 01KNOWLEDGE CHECK
What is the central performance problem described in this issue?
TEST YOUR UNDERSTANDING
MISSION STATUS
Track your progress as you investigate.