Running simultaneous queries with relations stalls typeorm

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:

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

I ran into an issue where typeorm would just stop responding occasionally, and when looking at the postgres stats I noticed that typeorm kept 10 (the size of the pool) connections open and in idle and didn’t seem to ever close them afterwards.

The connections showed up as Idle | WaitEvent: Client: ClientRead.

Some more investigations seem to indicate that it the issue presents itself when trying to find entities with relations (with the getManager().find(Entity, options) syntax).

Increasing the pool size can help mitigate the problem, and using the query builder works as a workaround, but is obviously something we’d want to avoid as much as possible in favour of shorter, and clearer syntax.

I don’t believe it’s a config issue either

let entities = ['./dist/api/src/entities/**/*.js'];

module.exports = {
  type: 'postgres',
  synchronize, // True locally
  ssl,
  host,
  database,
  username,
  password,
  entities,
  timezone: 'Z',
  logging,
  logger,
  maxQueryExecutionTime: 1000,
  extra: {
    poolSize, // 10
    idleTimeoutMillis: 5000, // Drop connections that are stalled
    connectionTimeoutMillis: 10000, // Drop connections that are stalled
  },

  cli: {
    entitiesDir: 'api/src/entities/**',
    migrationsDir: 'api/src/migration',
    subscribersDir: 'api/src/subscriber',
  },
};

Steps to reproduce or a small repository showing the problem:

/* eslint-disable @typescript-eslint/no-use-before-define */
import { createConnection, Entity, getManager, ManyToOne, OneToMany, PrimaryGeneratedColumn } from 'typeorm';

@Entity()
export class Entity2 {
  @PrimaryGeneratedColumn()
  id!: number;

  @ManyToOne(() => Entity1, ent1 => ent1.ent2)
  ent1!: Entity1;
}

@Entity()
export class Entity1 {
  @PrimaryGeneratedColumn()
  id!: number;

  @OneToMany(() => Entity2, ent2 => ent2.ent1)
  ent2!: Entity2[];
}

const getWithRelations = () => {
  getManager()
    .find(Entity1, { relations: { ent2: true } })
    .then(e => {
      console.log(e);
    });
};

const getSimple = () => {
  getManager()
    .find(Entity1)
    .then(console.log);
};

const getWithQb = () => {
  getManager()
    .getRepository(Entity1)
    .createQueryBuilder('ent')
    .leftJoinAndSelect('ent.ent2', 'ent2')
    .getMany()
    .then(console.log);
};

(async () => {
  await createConnection();

  const parent = await getManager().save(new Entity1());

  const child1 = new Entity2();
  child1.ent1 = parent;
  await getManager().save(child1);

  const child2 = new Entity2();
  child2.ent1 = parent;
  await getManager().save(child2);

  for (let i = 0; i < 35; i++) {
    getWithRelations(); // Will stall
  }

  for (let i = 0; i < 35; i++) {
    getSimple(); // Runs as expected
  }

  for (let i = 0; i < 35; i++) {
    getWithQb(); // Runs as expected
  }
})();

[mkeemon]

@Stene3 I have been running into the same issue using relationLoadStrategy: 'query'. The connection pool seems to be at the heart of the issue. I increased the max pool size to 50 against my local Postgres instance, and no longer run into the app locking up. Not a solution by any means, but helpful in debugging.

[Stene3]

Same happenned to me. Seems like issue with relations loading when relationLoadStrategy of type query is used. Single queries works, but more concurrently connections cause typeorm, and most probably all connection in pool, to be stalled. Any idea what could be the reason? I was trying to debug but no luck yet.