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feat: increase the default value of pingTimeout
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This value was updated from 60000 to 5000 in [1], included in
`engine.io@3.2.0` (Feb 2018).

The reasoning back then:

Some users experienced long delays between disconnection on the
server-side and on the client-side. The "disconnect" event would take a
long time to fire in the browser, probably due to a timer being
delayed. Hence the change.

That being said, the current value (5s) now causes unexpected
disconnections when a big payload is sent over a slow network, because
it prevents the ping-pong packets from being exchanged between the
client and the server. This can also happen when a synchronous task
blocks the server for more than 5 seconds.

The new value (20s) thus seems like a good balance between quick
disconnection detection and tolerance to various delays.

Note: pingInterval + pingTimeout is still below the threshold of React
Native, which complains if a timer is set with a delay of more than 1
minute.

[1]: 65b1ad1

Related:

- socketio/socket.io#2770
- socketio/socket.io#2769
- socketio/socket.io#3054
- socketio/socket.io#3376

Backported from 5a7fa13
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darrachequesne committed Jun 6, 2022
1 parent 1f5d469 commit f55a79a
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2 changes: 1 addition & 1 deletion README.md
Original file line number Diff line number Diff line change
Expand Up @@ -221,7 +221,7 @@ to a single process.
- `Object`: optional, options object
- **Options**
- `pingTimeout` (`Number`): how many ms without a pong packet to
consider the connection closed (`5000`)
consider the connection closed (`20000`)
- `pingInterval` (`Number`): how many ms before sending a new ping
packet (`25000`)
- `upgradeTimeout` (`Number`): how many ms before an uncompleted transport upgrade is cancelled (`10000`)
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2 changes: 1 addition & 1 deletion lib/server.js
Original file line number Diff line number Diff line change
Expand Up @@ -37,7 +37,7 @@ function Server (opts) {
opts = opts || {};

this.wsEngine = opts.wsEngine || process.env.EIO_WS_ENGINE || 'ws';
this.pingTimeout = opts.pingTimeout || 5000;
this.pingTimeout = opts.pingTimeout || 20000;
this.pingInterval = opts.pingInterval || 25000;
this.upgradeTimeout = opts.upgradeTimeout || 10000;
this.maxHttpBufferSize = opts.maxHttpBufferSize || 1e6;
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