Postmortem Report: The Great Database Connection Crisis š¢
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 thereās only one bus with five seats. Thatās 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!"āOur monitoring system sent an SOS signal, showing that database queries were taking longer than a toddlerās 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 couldnāt 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 BOOMāproblem 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 didnāt 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: Weāll keep a closer eye on connection usage, so we donāt get caught off guard again.
Configuration Reviews: No more āset it and forget it.ā Weāll regularly review and tweak our settings to match our traffic.
Load Testing: Weāll simulate heavy traffic more often to catch potential issues before they catch us.
Task List:
Patch the Connection Pool:
Apply the new settings across all environments to keep everything running smoothly.Add Connection Usage Monitoring:
Set up alarms for when weāre nearing capacity, so we can act before itās too late.Schedule Regular Load Tests:
Quarterly stress tests to make sure our system can handle peak loads without breaking a sweat.Revamp Configuration Management:
From now on, every change gets a double-check to avoid another crisis like this.