Google Cloud Function don't publish on PubSub, Timeout exceeded - node.js

Question

first thanks for reading this and try to answer it :)
On GCP (Google Cloud Plateform), i've got a database stored on cloud SQL,
2 Cloud functions, the first one is used to make a request on the database (this request can have more that 1000 result) then publish the result on PubSub, and the second one is used to do web scraping thanks to puppeteer.
first cloud functions code:
//[Requirement]
const mysql = require('mysql')
const {SecretManagerServiceClient} = require('#google-cloud/secret-manager')
const ProjectID = process.env.secretID
const SqlPass = `projects/xxx`
const client = new SecretManagerServiceClient()
const {PubSub} = require('#google-cloud/pubsub');
const pubSubClient = new PubSub();
const topicName = "xxxxxx";
//[/Requirement]
exports.LaunchAudit = async () => {
const dbSocketPath = "/cloudsql"
const DB_USER = "xxx"
const DB_PASS = await getSecret()
const DB_NAME = "xxx"
const CLOUD_SQL_CONNECTION_NAME = "xxx"
//[SQL CONNEXION]
let pool = mysql.createPool({
connectionLimit: 1,
socketPath: `${dbSocketPath}/${CLOUD_SQL_CONNECTION_NAME}`,
user: DB_USER,
password: DB_PASS,
connectTimeout: 500,
database: DB_NAME
})
//[/SQL CONNEXION]
//set the request
let sql = `select * from * where *;`
//make the setted request
await pool.query(sql, async (e,results) => {
//if there is an error send it
if(e){
throw e
}
//for each result of the query, log it and publish on PubSub ("Audit-property" topic)
results.forEach(async element => {
console.log(JSON.stringify(element))
await msgPubSub(JSON.stringify(element))
})
})
}
async function msgPubSub(data){
//console.log(data)
const messageBuffer = Buffer.from(data)
try {
const topicPublisher = await pubSubClient.topic(topicName).publish(messageBuffer)
console.log("Message id: " + topicPublisher)
} catch (error) {
console.error(`Error while publishing message: ${error.message}`)
}
}
firstly, when it works, it takes long to publish on PubSub topic the first message, something like 6 minutes, why there is this delay ? And When i do a big request (something like 500+ result) i've got a Timeout error : Total timeout of API google.pubsub.v1.Publisher exceeded 600000 milliseconds before any response was received.
I've tried to publish a batched message, add some memory to the cloud functions, use google-gax, but got the same result.
i'm using nodejs10.
2nd cloud functions message part code:
exports.MainAudit = async message => {
const property = Buffer.from(message.data, 'base64').toString()
const pProperty = JSON.parse(property)
console.log(property)
}
package.json dependencies:
"dependencies": {
"#google-cloud/pubsub": "^2.6.0",
"#google-cloud/secret-manager": "^3.2.0",
"google-gax": "^2.9.2",
"mysql": "^2.18.1",
"node-fetch": "^2.6.1"
}
Log + Timestamp:

Answer 1

As the code is now, you are creating a new instance of a publisher for each message you publish. This is because pubSubClient.topic(topicName) creates an instance for publishing to the topic. Therefore, you are paying the overhead of establishing a connection for each message you send. Instead, you'd want to create that object a single time and reuse it:
const pubSubClient = new PubSub();
const topicName = "xxxxxx";
const topicPublisher = pubSubClient.topic(topicName)
However, this still leaves an inefficiency in your application where you are waiting for each message to publish before starting the next publish due to the use of await on the publish call and the call to msgPubSub. The Pub/Sub client library can batch messages togetherr for more efficient sending, but you'd need to allow multiple calls to publish to be outstanding to take advantage of it. You'd want to await on a Promise.all of the list of promises returned from publishing.