Postmortem Report: The Great Database Connection Crisis šŸ¢

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3 min read

Issue Summary

Duration:

  • Start: August 17, 2024, 14:00 UTC

  • End: August 17, 2024, 16:30 UTC
    (Yes, it was a long and painful 2 hours and 30 minutes!)

Impact:
Imagine trying to board a bus with a thousand other people, but thereā€™s only one bus with five seats. Thatā€™s what our users experienced: 80% of them were stuck waiting in line, unable to log in or perform transactions. Error messages were everywhere, and frustration levels were through the roof.

Root Cause:
A small but mighty misconfiguration in the database connection pool. We set the maximum connections to a level that even a tortoise could outpace, leaving users stranded without a way in.

Timeline

  • 14:00 UTC:
    "Houston, we have a problem!"ā€”Our monitoring system sent an SOS signal, showing that database queries were taking longer than a toddlerā€™s nap.

  • 14:05 UTC:
    An engineer checked the logs and saw a flood of failed requests. Cue the dramatic background music.

  • 14:10 UTC:
    First suspicion: Network issues. "Is the internet broken?" Nope, everything checked out fine. The plot thickens.

  • 14:30 UTC:
    We started looking into recent changes, including a tweak in the database connection pool. "Nah, that couldnā€™t be it...could it?"

  • 15:00 UTC:
    After chasing wild geese and red herrings, we circled back to the connection pool. Ding ding ding! We found our culprit: an embarrassingly low max connection setting.

  • 15:15 UTC:
    Time to call in the big guns: the database team. "Help! Our database is slower than dial-up!"

  • 15:30 UTC:
    They swooped in, adjusted the settings, and BOOMā€”problem solved! The tortoise finally decided to run.

  • 16:00 UTC:
    The system was back up, users could log in, and the sun shone once again.

  • 16:30 UTC:
    We beefed up our monitoring, poured a coffee, and took a much-needed break.

Root Cause and Resolution

Root Cause:
The connection pool was configured to allow fewer connections than a kiddie pool. This led to a scenario where every user was fighting for the same few slots, causing a massive bottleneck. The database was overbooked, and we were left with a digital traffic jam.

Resolution:
We bumped up the maximum number of connections to a more reasonable number, so everyone could get a seat on the bus. We also tightened up the connection timeout settings to ensure that idle connections didnā€™t overstay their welcome. Problem solved, and the database was back to running smoother than butter on a hot pancake.

Corrective and Preventative Measures

Improvements Needed:

  • Enhanced Monitoring: Weā€™ll keep a closer eye on connection usage, so we donā€™t get caught off guard again.

  • Configuration Reviews: No more ā€œset it and forget it.ā€ Weā€™ll regularly review and tweak our settings to match our traffic.

  • Load Testing: Weā€™ll simulate heavy traffic more often to catch potential issues before they catch us.

Task List:

  1. Patch the Connection Pool:
    Apply the new settings across all environments to keep everything running smoothly.

  2. Add Connection Usage Monitoring:
    Set up alarms for when weā€™re nearing capacity, so we can act before itā€™s too late.

  3. Schedule Regular Load Tests:
    Quarterly stress tests to make sure our system can handle peak loads without breaking a sweat.

  4. Revamp Configuration Management:
    From now on, every change gets a double-check to avoid another crisis like this.

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