I have two apps connected to the Postgres database, each with a connection pool size of 20.

const db: any = {
type: 'postgres',
url: DATABASE_URL,
entities: [${__dirname}/entity/*.entity{.ts,.js}],
migrations: [${__dirname}/migrations/*{.ts,.js}],
logging: 'all',
extra: {
max: 20,
min: 5,
idleTimeoutMillis: 30000,
connectionTimeoutMillis: 10000
}
};

But running a stress test with k6 browser, I get this error with around 3-4k users calling 3 endpoints, 1 of them being cache 95% of the time:

Timeout exceeded when trying to connect [
Apr 06 23:23:03
'Error: timeout exceeded when trying to connect\n' +
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' at Timeout.onTimeout (/app/nodemodules/pg-pool/index.js:205:27)\n' +
Apr 06 23:23:03
' at listOnTimeout (node:internal/timers:594:17)\n' +
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' at process.processTimers (node:internal/timers:529:7)',
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'ExceptionsHandler'
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]
Apr 06 23:23:03
2025-04-07T03:22:55.583Z [error] - timeout exceeded when trying to connect

That makes the API and database unresponsive.