问题
How long does it take for a message from Google Cloud Messaging to arrive on a device?
I want to link my door bell with my Android App. The door bell I receive on a RaspberryPi which has an internet connection. I could connect to Google Cloud Messaging, but would the message arrive soon on my Android device?
回答1:
Almost immediately (1-2sec) if phone is active and has stable internet connection. But there is no 100% guarantee. If phone is sleeping it can take time. If you forgot to pay your carrier bills it will never come.
回答2:
After months of using in on a production application I've come to notice that it's not so reliable. I've noticed it can take up to 20 minutes to receive a notification. I feel like I was getting much better speed and reliability from sending out an SMS text message.
Yes, it usually comes in a few seconds. But sometimes it can take a while.
来源：https://stackoverflow.com/questions/14790382/how-long-does-it-take-for-a-message-from-google-cloud-messaging-to-arrive-on-dev