Shadow traffic and comparison
On This Lesson 4 topics
This lesson is planned. The outline below lists the topics it will cover. The full lesson has not been published yet.
In this lesson
compare old and new paths in production without affecting users.
Planned topics
- Shadow traffic: send a copy of requests to the new path and discard its answer, or compare it with the old one.
- Compare results and measure mismatch rate; classify mismatches (expected differences versus bugs).
- Be careful with side effects: shadow paths must not write, send messages, or charge.
- Measure latency and load impact of the shadow itself.
- Set a mismatch threshold for cut-over in advance.
Draft outline details
Demonstration
A comparison report: total compared, matches, mismatches by category (timing, format, missing data, bug), trend per day against the threshold.
Check your understanding
What must a shadow path never do?
Show answer
Cause side effects such as writes, messages, or payments.
Practice
Apply this lesson with the module's lab, exercises and quiz.
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