Express callback delaying with setTimeout

Question

Express callback delaying with setTimeout

I'm working on a route that involves setting a data attribute called "active" to true initially, but then switching it to false after an hour. I'm curious if it's considered bad practice or feasible to use a setTimeout function within the express callback function like this:

app.get("/test", (req, res) => {

//Some code

SetTimeout(func, 3600);
});

I'm concerned about scalability - if this route is accessed frequently, will it become too costly? Appreciate any insights on this matter. Thanks!

javascript express web-development-server

Answer 1

Answer №1

When storing values in a database, it is not recommended to create a timer for each entry in the node that resets the value. This is especially true for long-lasting timers. Session-like or related data that needs to persist for longer periods should not be held in the memory of the node process.

If your site receives frequent visitors, there may be multiple timers running concurrently. Restarting the application can either result in losing these timers or require waiting until they finish before accepting any new ones.

Switching to clustered mode is not a viable solution as calling a route twice could lead to the requests being handled by different processes, causing inconsistencies with timeouts set by each process.

A more efficient approach would be to add a timestamp to the database and implement a cleanup timer that manages all entries.

Answer 2

When storing values in a database, it is not recommended to create a timer for each entry in the node that resets the value. This is especially true for long-lasting timers. Session-like or related data that needs to persist for longer periods should not be held in the memory of the node process.

If your site receives frequent visitors, there may be multiple timers running concurrently. Restarting the application can either result in losing these timers or require waiting until they finish before accepting any new ones.

Switching to clustered mode is not a viable solution as calling a route twice could lead to the requests being handled by different processes, causing inconsistencies with timeouts set by each process.

A more efficient approach would be to add a timestamp to the database and implement a cleanup timer that manages all entries.

Answer 3

Answer №2

It appears that setting one timer may be sufficient in this case, assuming the 'hour' begins with the initial request.

let timer = null
let data = true

app.get("/test", (req, res) => {

  //Some code
  if (!timer) {
    timer = setTimeout(() => {data=false}, 3600);
  }
});

Alternatively, for multiple users, it is possible to avoid setting numerous timers by utilizing a hash with timestamps and checking it for each request or using a separate interval timer.

// init
let timers = {}

// in request
if (!timers[user]) {
    timers[user] = new Date().getTime() / 1000 + 3600
}
else if (timers[user] <= new Date().getTime() / 1000)
{
    // update db, etc
}


// or poll for expirations in separate single timer routine
let now = new Date().getTime() / 1000
Object.keys(timers).forEach(user => {
  if (timers[user] <= now) {
    // update db, etc
  }
})

Answer 4

It appears that setting one timer may be sufficient in this case, assuming the 'hour' begins with the initial request.

let timer = null
let data = true

app.get("/test", (req, res) => {

  //Some code
  if (!timer) {
    timer = setTimeout(() => {data=false}, 3600);
  }
});

Alternatively, for multiple users, it is possible to avoid setting numerous timers by utilizing a hash with timestamps and checking it for each request or using a separate interval timer.

// init
let timers = {}

// in request
if (!timers[user]) {
    timers[user] = new Date().getTime() / 1000 + 3600
}
else if (timers[user] <= new Date().getTime() / 1000)
{
    // update db, etc
}


// or poll for expirations in separate single timer routine
let now = new Date().getTime() / 1000
Object.keys(timers).forEach(user => {
  if (timers[user] <= now) {
    // update db, etc
  }
})

Express callback delaying with setTimeout

Answer №1

Answer №2

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