CODEWITHSUNDEEP
node.jsmongodb
mahendra
mahendra

Reputation: 203

What is the use of Nodejs mongodb driver keepAlive option?

I'm having hard time understanding keepAlive option passed to nodeJS mongo driver. this docs says keepAlive takes boolean value and keepAliveInitialDelay is used to wait before initiating keepAlive on the TCP socket

this docs says keepAlive takes an integer value and reads The number of milliseconds to wait before initiating keepAlive on the TCP socket.

I tried using both and failed to find any difference also I tried with both true and false values for keepAlive and tried 0,1 and 30000(default) for keepAliveInitialDelay.

  1. what is the correct way to use keepAlive?
  2. what does "initiating" keepAlive do? or what is the use of keepAlive option?
  3. why did it not make any difference even after setting keepAlive to false or settings it to 0 or 1?
  4. docs here state that keepAlive affects artefacts -> Server, ReplicaSet, Mongos. so to which option does it map to at server side docs?

I'm using mongo driver V3.3 and mongo atlas V4.2

Thanks in advance.

Upvotes: 3

Views: 7984

Answers (1)

D. SM
D. SM

Reputation: 14520

The TCP keep-alive mechanism is described here. It is used for:

  • Checking for dead peers

  • Preventing disconnection due to network inactivity

When keep-alive is enabled, the driver instructs the network stack to periodically send ping packets to the server on the established connection. If the server's network stack does not respond, the connection is flagged as failed.

Without keep-alive, the driver wouldn't find out about some of the network issues until after the application issued a query (and was waiting for it to be executed).

The driver sets the network stack options here using setKeepAlive.

To see whether keep-alives are being sent, you need to use a tool like tcpdump to inspect traffic on the connections established by the driver.

The server uses the system-wide keep-alive value if it is under 300 seconds, otherwise sets keep-alive interval to 300 seconds.

Upvotes: 2

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