How I Stopped Node.js from Freezing While Bulk-Processing 1,500+ Excel Rows

A Node.js Excel bulk import was optimized after 1,500 student rows overwhelmed the app in a single sequential loop.

The original flow mixed bcrypt hashing, Postgres writes, and SMTP emails inline, causing timeouts and connection pressure.

The fix kept database writes inside one transaction with per-row SAVEPOINTs for partial rollback.

Email jobs were collected during import and sent only after the transaction finished, separating slow external work from DB transactions.