CODEWITHSUNDEEP
mongodb
mpc75
mpc75

Reputation: 989

Why does my mongoDB account have 292 connections?

I only write data into my mongoDB database once a day and I am not currently writing any data into it but there have been a consistent 292 connections into my database for the past three hours. No reads or writes, just connections and a consistent 29 commands per second since this started.

Concerned by this, I adjusted settings to only allow access from one specific IP, and changed all my passwords but the number hasn't changed, still 292 connections and 29 commands per second. Any idea what is causing this or perhaps how I can dig in further?

Upvotes: 0

Views: 154

Answers (1)

Manuel
Manuel

Reputation: 15042

The number of connections depends on the cluster setup. A connection can be external (e.g. your app or monitoring tools) or internal (e.g. to replicate your data to secondary nodes or a backup process).

You can use db.currentOp() to list the active connections.

Consider that you app instance(s) may not open just 1 connection, but several, depending on the driver that connects to the DB and how it handles connection pooling. The connection pool size can be thought of as the max number of concurrent requests that your driver can service. For example, the default connection pool size for the Node.js MongoDB driver is 5. If you have set a high pool size, either with the driver or connection string, your app may open many connections to concurrently process the write commands.

You can start by process of elimination:

  • Completely cut your app off from the DB. There is a keep-alive time, so connections won‘t close immediately unless the driver closes them formally. You may have to wait some time, depending on the keep-alive setting. You can also restart your cluster and see how many connections there are initially.

  • Connect you app to the DB and check how the connection number changes with each request. Check whether your app properly closes connections to the DB at some point after opening them.

Upvotes: 1

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