FCM“ Firebase”的延迟，有时可以无延迟地运行

Question

我在FCM中发现错误。通知会延迟数小时或数分钟，有时会立即延迟，而不会更改代码或互联网速度或其他原因，因此我无法理解发生了什么。在Firebase https://imgur.com/1pi20fG

中有SS显示我的功能控制台

'use strict'


const functions = require('firebase-functions');
const admin = require('firebase-admin');
admin.initializeApp(functions.config().firebase);


exports.sendNotification = functions.database.ref('/Noti/{receiver_user_id}/{notification_id}')
.onWrite((data, context) =>
{
    const receiver_user_id = context.params.receiver_user_id;
    const notification_id = context.params.notification_id;


    console.log('We have a notification to send to :' , receiver_user_id);


    if (!data.after.val()) 
    {
        console.log('A notification has been deleted :' , notification_id);
        return null;
    }

    const DeviceToken = admin.database().ref(`/userstoken/${receiver_user_id}/token`).once('value');

    return DeviceToken.then(result => 
    {
        const token_id = result.val();

        const payload = 
        {
            notification:
            {
                title: "New ",
                body: `you have a new Chat Request, Please Check.`,
                icon: "default"
            }
        };

        return admin.messaging().sendToDevice(token_id, payload)
        .then(response => 
            {
                console.log('This was a notification feature.');
            });
    });
});