Run Latency Tests

Table of Contents

1. CLI Test (Node.js)
   1. Sample Output
2. Browser Test (Angular)
3. Blob Latency Breakdown
4. Test from Different Locations

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CLI Test (Node.js)

The fastest way to measure WebSocket latency:

# From repo root
npm install ws
node ws-latency-test.js

This connects to all 14 VMs, sends 5 echo pings each, and reports avg/min/max RTT.

Sample Output

=== WebSocket Latency Test Results ===

Region                         Avg   Min   Max
------------------------------  ---   ---   ---
Indonesia Central               20    17    23
Southeast Asia                  36    33    43
Malaysia West                   39    33    43
East Asia                       69    67    72
...

Browser Test (Angular)

For interactive testing with the Angular dashboard:

cd ui
npm install
ng serve

Open http://localhost:4200 — the dashboard tests WebSocket, HTTP, and Blob latency simultaneously.

Blob Latency Breakdown

To see where blob latency is spent (DNS vs TLS vs TTFB):

curl -o /dev/null -s -w "dns:%{time_namelookup}s tls:%{time_appconnect}s ttfb:%{time_starttransfer}s total:%{time_total}s\n" \
  "https://latencyindonesiacentral.z45.web.core.windows.net/latency-test.json"

Test from Different Locations

Results vary based on your physical location. To test from the cloud:

# Run test from one of the VMs using az vm run-command
az vm run-command invoke \
  --resource-group rg-latency-southeastasia \
  --name vm-latency-southeastasia \
  --command-id RunShellScript \
  --scripts "curl -o /dev/null -s -w '%{time_total}' https://latencyindonesiacentral.z45.web.core.windows.net/latency-test.json"

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