---
id: e7367a83-f654-4b21-8e2b-e98bc85a7da7
---

# MongoDB cursors timeouts incident
---

The MongoDB cursors timeouts incident refers to an issue where too many cursors are timing out in a MongoDB instance. This can cause disruptions in the normal functioning of the database and lead to delays in processing queries. This incident type requires immediate attention from the software engineer to resolve the issue and prevent any further damage to the system.

### Parameters
```shell
# Environment Variables

export DATABASE_NAME="PLACEHOLDER"

export CLIENT_ADDRESS="PLACEHOLDER"

export OPID="PLACEHOLDER"

export NEW_TIMEOUT_LIMIT="PLACEHOLDER"

```

## Debug

### Check if MongoDB is running
```shell
systemctl status mongod
```

### Check MongoDB logs for any errors related to cursors
```shell
tail -f /var/log/mongodb/mongod.log | grep 'cursor'
```

### Check the current number of open cursors
```shell
mongo ${DATABASE_NAME} --eval "printjson(db.serverStatus().cursors)"
```

### Check the number of cursors being used by a specific client
```shell
mongo ${DATABASE_NAME} --eval "printjson(db.currentOp({'client_s' : '${CLIENT_ADDRESS}'}))"
```

### Check the number of cursors being used by all clients
```shell
mongo ${DATABASE_NAME} --eval "printjson(db.currentOp({'active': true, 'op': 'query', 'ns': /${DATABASE_NAME}./, '$where': 'this.cursorInfo != null'}))"
```

### Kill a specific cursor
```shell
mongo ${DATABASE_NAME} --eval "db.killOp(${OPID})"
```

## Repair

### Increase the cursor timeout limit if necessary to prevent timeouts from occurring in the future.
```shell


#!/bin/bash



# Set the new cursor timeout limit

NEW_TIMEOUT_LIMIT=${NEW_TIMEOUT_LIMIT}



# Update the MongoDB configuration file with the new timeout limit

sudo sed -i "s/cursorTimeoutMillis:.*/cursorTimeoutMillis: $NEW_TIMEOUT_LIMIT/g" /etc/mongod.conf



# Restart the MongoDB service to apply the changes

sudo systemctl restart mongod


```


The MongoDB cursors timeouts incident refers to an issue where too many cursors are timing out in a MongoDB instance. This can cause disruptions in the normal functioning of the database and lead to delays in processing queries. This incident type requires immediate attention from the software engineer to resolve the issue and prevent any further damage to the system.


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```shell
# Environment Variables

export DATABASE_NAME="PLACEHOLDER"

export CLIENT_ADDRESS="PLACEHOLDER"

export OPID="PLACEHOLDER"

export NEW_TIMEOUT_LIMIT="PLACEHOLDER"

```


### Check if MongoDB is running

```shell
systemctl status mongod
```

### Check MongoDB logs for any errors related to cursors

```shell
tail -f /var/log/mongodb/mongod.log | grep 'cursor'
```

### Check the current number of open cursors

```shell
mongo ${DATABASE_NAME} --eval "printjson(db.serverStatus().cursors)"
```

### Check the number of cursors being used by a specific client

```shell
mongo ${DATABASE_NAME} --eval "printjson(db.currentOp({'client_s' : '${CLIENT_ADDRESS}'}))"
```

### Check the number of cursors being used by all clients

```shell
mongo ${DATABASE_NAME} --eval "printjson(db.currentOp({'active': true, 'op': 'query', 'ns': /${DATABASE_NAME}./, '$where': 'this.cursorInfo != null'}))"
```

### Kill a specific cursor

```shell
mongo ${DATABASE_NAME} --eval "db.killOp(${OPID})"
```


### Increase the cursor timeout limit if necessary to prevent timeouts from occurring in the future.

```shell


#!/bin/bash



# Set the new cursor timeout limit

NEW_TIMEOUT_LIMIT=${NEW_TIMEOUT_LIMIT}



# Update the MongoDB configuration file with the new timeout limit

sudo sed -i "s/cursorTimeoutMillis:.*/cursorTimeoutMillis: $NEW_TIMEOUT_LIMIT/g" /etc/mongod.conf



# Restart the MongoDB service to apply the changes

sudo systemctl restart mongod


```


MongoDB cursors timeouts incident

Overview

Parameters

Debug

Check if MongoDB is running

Check the current number of open cursors

Check the number of cursors being used by a specific client

Check the number of cursors being used by all clients

Kill a specific cursor

Repair

Increase the cursor timeout limit if necessary to prevent timeouts from occurring in the future.

Learn more

Related Runbooks

Tomcat High JDBC Connection Pool Usage Incident.

Redis too many masters incident

Postgresql high rate statement timeout incident.

Postgresql not enough connections incident

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