Check the current number of connections to MongoDb

问题:

What is the command to get the number of clients connected to a particular MongoDB server?

回答1:

connect to the admin database and run db.serverStatus():

> var status = db.serverStatus()
> status.connections
   {"current" : 21, "available" : 15979}
> 

You can directly get by querying

db.serverStatus().connections

To understand what does MongoDb's db.serverStatus().connections response mean, read the documentation here.

connections

"connections" : {
   "current" : <num>,
   "available" : <num>,
   "totalCreated" : NumberLong(<num>)
},

connections A document that reports on the status of the connections. Use these values to assess the current load and capacity requirements of the server.

connections.current The number of incoming connections from clients to the database server . This number includes the current shell session. Consider the value of connections.available to add more context to this datum.

The value will include all incoming connections including any shell connections or connections from other servers, such as replica set members or mongos instances.

connections.available The number of unused incoming connections available. Consider this value in combination with the value of connections.current to understand the connection load on the database, and the UNIX ulimit Settings document for more information about system thresholds on available connections.

connections.totalCreated Count of all incoming connections created to the server. This number includes connections that have since closed.

回答2:

db.serverStatus() gives no of connections opend and avail but not shows the connections from which client. For more info you can use this command sudo lsof | grep mongod | grep TCP. I need it when i did replication and primary node have many client connection greater than secondary.

$ sudo lsof | grep mongod | grep TCP
mongod    5733             Al    6u     IPv4 0x08761278       0t0       TCP *:28017 (LISTEN)
mongod    5733             Al    7u     IPv4 0x07c7eb98       0t0       TCP *:27017 (LISTEN)
mongod    5733             Al    9u     IPv4 0x08761688       0t0       TCP 192.168.1.103:27017->192.168.1.103:64752 (ESTABLISHED)
mongod    5733             Al   12u     IPv4 0x08761a98       0t0       TCP 192.168.1.103:27017->192.168.1.103:64754 (ESTABLISHED)
mongod    5733             Al   13u     IPv4 0x095fa748       0t0       TCP 192.168.1.103:27017->192.168.1.103:64770 (ESTABLISHED)
mongod    5733             Al   14u     IPv4 0x095f86c8       0t0       TCP 192.168.1.103:27017->192.168.1.103:64775 (ESTABLISHED)
mongod    5733             Al   17u     IPv4 0x08764748       0t0       TCP 192.168.1.103:27017->192.168.1.103:64777 (ESTABLISHED)

This shows that I currently have five connections open to the MongoDB port (27017) on my computer. In my case I'm connecting to MongoDB from a Scalatra server, and I'm using the MongoDB Casbah driver, but you'll see the same lsof TCP connections regardless of the client used (as long as they're connecting using TCP/IP).

回答3:

I tried to see all connections for mongo database by following command.

netstat -anp --tcp --udp | grep mongo

This command can show every tcp connection for mongodb in more detail.

tcp        0      0 10.26.2.185:27017           10.26.2.1:2715              ESTABLISHED 1442/./mongod       
tcp        0      0 10.26.2.185:27017           10.26.2.1:1702              ESTABLISHED 1442/./mongod  
tcp        0      0 10.26.2.185:27017           10.26.2.185:39506           ESTABLISHED 1442/./mongod       
tcp        0      0 10.26.2.185:27017           10.26.2.185:40021           ESTABLISHED 1442/./mongod       
tcp        0      0 10.26.2.185:27017           10.26.2.185:39509           ESTABLISHED 1442/./mongod 
tcp        0      0 10.26.2.185:27017           10.26.2.184:46062           ESTABLISHED 1442/./mongod       
tcp        0      0 10.26.2.185:27017           10.26.2.184:46073           ESTABLISHED 1442/./mongod       
tcp        0      0 10.26.2.185:27017           10.26.2.184:46074           ESTABLISHED 1442/./mongod   

回答4:

In OS X, too see the connections directly on the network interface, just do:

$ lsof -n -i4TCP:27017

mongod     2191 inanc    7u  IPv4 0xab6d9f844e21142f  0t0  TCP 127.0.0.1:27017 (LISTEN)
mongod     2191 inanc   33u  IPv4 0xab6d9f84604cd757  0t0  TCP 127.0.0.1:27017->127.0.0.1:56078 (ESTABLISHED)
stores.te 18704 inanc    6u  IPv4 0xab6d9f84604d404f  0t0  TCP 127.0.0.1:56078->127.0.0.1:27017 (ESTABLISHED)

• No need to use grep etc, just use the lsof's arguments.

• Too see the connections on MongoDb's CLI, see @milan's answer (which I just edited).

回答5:

Also some more details on the connections with: db.currentOp(true)

Taken from: https://jira.mongodb.org/browse/SERVER-5085

回答6:

Connect to MongoDB using mongo-shell and run following command.

db.serverStatus().connections

e.g:

mongo> db.serverStatus().connections
{ "current" : 3, "available" : 816, "totalCreated" : NumberLong(1270) }

回答7:

db.runCommand( { "connPoolStats" : 1 } )

{
    "numClientConnections" : 0,
    "numAScopedConnections" : 0,
    "totalInUse" : 0,
    "totalAvailable" : 0,
    "totalCreated" : 0,
    "hosts" : {

    },
    "replicaSets" : {

    },
    "ok" : 1
}

回答8:

Connect with your mongodb instance from local system

1. sudo mongo "mongodb://MONGO_HOST_IP:27017" --authenticationDatabase admin

It ll let you know all connected clients and their details

2. db.currentOp(true)