Bun MySQL Repro

Minimal standalone repro for Bun MySQL connection instability in a cache-like workload.

Requirements

Set environment variables:

• MYSQL_HOST
• MYSQL_USER
• MYSQL_PASSWORD
• MYSQL_DATABASE
• optional: MYSQL_PORT
• optional: MYSQL_TLS (true or false, default false)

Run

Default scenario (single connection for reads+writes, transactional write):

REPRO_MODE=single REPRO_TX=true REPRO_ROWS=30000 REPRO_BATCH=500 bun scripts/bun-mysql-repro/repro.ts

Split read/write connections:

REPRO_MODE=split REPRO_TX=true REPRO_ROWS=30000 REPRO_BATCH=500 bun scripts/bun-mysql-repro/repro.ts

Autocommit write (no transaction):

REPRO_MODE=single REPRO_TX=false REPRO_ROWS=30000 REPRO_BATCH=100 bun scripts/bun-mysql-repro/repro.ts

What it does

1. Creates two repro tables:
   • bun_repro_cached_ranges
   • bun_repro_cached_inventory_movements
2. Clears scenario-specific rows
3. Reads range metadata
4. Writes a large batch of movement rows
5. Reads rows back

If the runtime fails, output typically stops mid-step (or reports MySQLError: Connection closed).

Notes

• This script is intentionally independent of app code.
• It uses only Bun.SQL and MySQL.