node-postgres/packages/pg-pool/test/sizing.js

const expect = require('expect.js')
const co = require('co')
const _ = require('lodash')

const describe = require('mocha').describe
const it = require('mocha').it

const Pool = require('../')

describe('pool size of 1', () => {
  it(
    'can create a single client and use it once',
    co.wrap(function* () {
      const pool = new Pool({ max: 1 })
      expect(pool.waitingCount).to.equal(0)
      const client = yield pool.connect()
      const res = yield client.query('SELECT $1::text as name', ['hi'])
      expect(res.rows[0].name).to.equal('hi')
      client.release()
      pool.end()
    })
  )

  it(
    'can create a single client and use it multiple times',
    co.wrap(function* () {
      const pool = new Pool({ max: 1 })
      expect(pool.waitingCount).to.equal(0)
      const client = yield pool.connect()
      const wait = pool.connect()
      expect(pool.waitingCount).to.equal(1)
      client.release()
      const client2 = yield wait
      expect(client).to.equal(client2)
      client2.release()
      return yield pool.end()
    })
  )

  it(
    'can only send 1 query at a time',
    co.wrap(function* () {
      const pool = new Pool({ max: 1 })

      // the query text column name changed in PostgreSQL 9.2
      const versionResult = yield pool.query('SHOW server_version_num')
      const version = parseInt(versionResult.rows[0].server_version_num, 10)
      const queryColumn = version < 90200 ? 'current_query' : 'query'

      const queryText = 'SELECT COUNT(*) as counts FROM pg_stat_activity WHERE ' + queryColumn + ' = $1'
      const queries = _.times(20, () => pool.query(queryText, [queryText]))
      const results = yield Promise.all(queries)
      const counts = results.map((res) => parseInt(res.rows[0].counts, 10))
      expect(counts).to.eql(_.times(20, (i) => 1))
      return yield pool.end()
    })
  )

  it(
    'does not remove clients when at or below min',
    co.wrap(function* () {
      const pool = new Pool({ max: 1, min: 1, idleTimeoutMillis: 10 })
      const client = yield pool.connect()
      client.release()
      yield new Promise((resolve) => setTimeout(resolve, 20))
      expect(pool.idleCount).to.equal(1)
      return yield pool.end()
    })
  )

  it(
    'does remove clients when at or below min if maxUses is reached',
    co.wrap(function* () {
      const pool = new Pool({ max: 1, min: 1, idleTimeoutMillis: 10, maxUses: 1 })
      const client = yield pool.connect()
      client.release()
      yield new Promise((resolve) => setTimeout(resolve, 20))
      expect(pool.idleCount).to.equal(0)
      return yield pool.end()
    })
  )

  it(
    'does remove clients when at or below min if maxLifetimeSeconds is reached',
    co.wrap(function* () {
      const pool = new Pool({ max: 1, min: 1, idleTimeoutMillis: 10, maxLifetimeSeconds: 1 })
      const client = yield pool.connect()
      client.release()
      yield new Promise((resolve) => setTimeout(resolve, 1020))
      expect(pool.idleCount).to.equal(0)
      return yield pool.end()
    })
  )
})

describe('pool size of 2', () => {
  it(
    'does not remove clients when at or below min',
    co.wrap(function* () {
      const pool = new Pool({ max: 2, min: 2, idleTimeoutMillis: 10 })
      const client = yield pool.connect()
      const client2 = yield pool.connect()
      client.release()
      yield new Promise((resolve) => setTimeout(resolve, 20))
      client2.release()
      yield new Promise((resolve) => setTimeout(resolve, 20))
      expect(pool.idleCount).to.equal(2)
      return yield pool.end()
    })
  )

  it(
    'does remove clients when above min',
    co.wrap(function* () {
      const pool = new Pool({ max: 2, min: 1, idleTimeoutMillis: 10 })
      const client = yield pool.connect()
      const client2 = yield pool.connect()
      client.release()
      yield new Promise((resolve) => setTimeout(resolve, 20))
      client2.release()
      yield new Promise((resolve) => setTimeout(resolve, 20))
      expect(pool.idleCount).to.equal(1)
      return yield pool.end()
    })
  )
})

describe('pool min size', () => {
  it(
    'does not drop below min when clients released at same time',
    co.wrap(function* () {
      const pool = new Pool({ max: 2, min: 1, idleTimeoutMillis: 10 })
      const client = yield pool.connect()
      const client2 = yield pool.connect()
      client.release()
      client2.release()
      yield new Promise((resolve) => setTimeout(resolve, 20))
      expect(pool.idleCount).to.equal(1)
      return yield pool.end()
    })
  )
})