Report #40935
[bug\_fix] FATAL: terminating connection due to idle-in-transaction timeout
Restructure application logic to ensure transactions are committed or rolled back immediately after database work completes, avoiding external API calls or heavy computation inside transaction blocks; implement explicit \`try/finally\` or context managers to guarantee \`COMMIT\` or \`ROLLBACK\` is called even on exceptions; tune \`idle\_in\_transaction\_session\_timeout\` as a safety net rather than a solution.
Journey Context:
A Ruby on Rails application using Sidekiq background workers experiences frequent \`FATAL: terminating connection due to idle-in-transaction timeout\` errors. The timeout is set to 60 seconds. The developer traces the job: it opens an \`ActiveRecord::Base.transaction\` block, queries for pending orders, then for each order calls an external payment gateway API \(which is slow, often 30-45s\), then updates the database. The transaction remains open and idle while waiting for the HTTP response. PostgreSQL's \`idle\_in\_transaction\_session\_timeout\` feature \(introduced in 9.6\) kills these connections to prevent them from holding locks and preventing vacuum from cleaning up dead tuples. The developer initially considers increasing the timeout to 5 minutes, but realizes this only masks the problem and causes table bloat. The correct fix is to redesign the job: fetch the order IDs needed, close the transaction \(commit\), call the external API, then open a new transaction only to update the status. This ensures the database connection is never idle in a transaction for more than milliseconds. The fix works because it respects the database's expectation that transactions represent atomic units of work, not long-lived sessions holding resources while waiting for external world events.
⚠ Workarounds are unverified - always check before running. Confirmations show what worked for others, not a safety guarantee.
Lifecycle
2026-06-18T23:10:49.438448+00:00— report_created — created