PostgresQueryRunner not handling idle connection errors

[joras]

Issue type:

[ ] question
[x] bug report
[ ] feature request
[ ] documentation issue

Database system/driver:

[ ] cordova
[ ] mongodb
[ ] mssql
[ ] mysql / mariadb
[ ] oracle
[x] postgres
[ ] cockroachdb
[ ] sqlite
[ ] sqljs
[ ] react-native
[ ] expo

TypeORM version:

[ x] latest
[ ] @next
[ ] 0.x.x (or put your version here)

Steps to reproduce or a small repository showing the problem:

PostgresQueryRunner is not handling idle connection errors, thus all the connection related errors are unhandled and process usually dies with unexpected error.

    at Connection.<anonymous> (/Users/jaan/Projects/typeormtest/node_modules/pg/lib/client.js:275:71)
    at Object.onceWrapper (events.js:417:28)
    at Connection.emit (events.js:311:20)
    at Connection.EventEmitter.emit (domain.js:482:12)
    at Socket.<anonymous> (/Users/jaan/Projects/typeormtest/node_modules/pg/lib/connection.js:126:10)
    at Socket.emit (events.js:323:22)
    at Socket.EventEmitter.emit (domain.js:482:12)
    at endReadableNT (_stream_readable.js:1204:12)
    at processTicksAndRejections (internal/process/task_queues.js:84:21)

It is not quite obvious when reading node-postgres documentation, but it is there under https://node-postgres.com/api/client - 'event' section. The client returned from pool.connect() must handle on('error') events because this is where idle connection error are returned. It seems pool.on('error') is not enough.

Also if you look node-postgres pool.query() function you can see they are handling on('error') and client.query() errors.

Now that said, the issue is made worse by a bug in in node-postgres - when idle connection error handler is not attached, client.query() does not actually throw at all brianc/node-postgres#2191 .

Of course if this issue is fixed without fixing #5112 the connection would be returned to the pool until the pool fills with broken connections.

Small example to play with, if you stop postgres, the exceptions are not caught and process dies :
https://gist.github.com/joras/03bf07a7eb0ab0f7bc755f15b510b432

[hotsezus]

I am experiencing wrong handling of first query after internet disconnection because of this bug. It just hangs for infinite time while all of the next queries are throwing correct exceptions which can be handled on other levels.
Handling of exactly the same case on node-postgres level is described here pg.Client -> events

// walk over to server, unplug network cable
// process output: 'something bad has happened!' followed by stacktrace :P

[imnotjames]

This has been merged so we're gonna close this out.