---
id: f67c78cd-d5b3-41fd-af5d-35f558370c96
---

# High incoming connections on MongoDB
---

This incident type typically involves a high volume of incoming connections to a MongoDB database, which can cause performance issues and potentially impact the availability of the database. It often requires investigation and remediation to prevent further issues.

### Parameters
```shell
# Environment Variables

export HOST="PLACEHOLDER"

export PORT="PLACEHOLDER"

export PATH_TO_MONGODB_LOG="PLACEHOLDER"

export MAX_CONNECTIONS="PLACEHOLDER"

```

## Debug

### Check MongoDB connection status
```shell
mongo ${HOST}:${PORT} --eval "db.runCommand({ping:1})"
```

### Check MongoDB connection limit
```shell
mongo ${HOST}:${PORT} --eval "db.runCommand({whatsmyuri:1}).limit"
```

### Check available MongoDB connections
```shell
mongo ${HOST}:${PORT} --eval "db.serverStatus().connections"
```

### Check MongoDB replication status
```shell
mongo ${HOST}:${PORT} --eval "rs.status()"
```

### Check current MongoDB read/write operations
```shell
mongo ${HOST}:${PORT} --eval "db.currentOp()"
```

### Check MongoDB system logs for any errors
```shell
tail -f /var/log/mongodb/mongod.log
```

### Check MongoDB configuration file for connection limits and timeouts
```shell
cat /etc/mongod.conf
```

## Repair

### Set the path to the MongoDB log file
```shell
LOG_FILE=${PATH_TO_MONGODB_LOG}
```

### Check if the log file exists
```shell
if [ ! -f "$LOG_FILE" ]; then

    echo "MongoDB log file not found."

    exit 1

fi
```

### Search the log file for entries related to incoming connections
```shell
grep "incoming connection" "$LOG_FILE"
```

### If no entries are found, exit with an error message
```shell
if [ $? -ne 0 ]; then

    echo "No incoming connection entries found in MongoDB log file."

    exit 1

fi
```

### If entries are found, print them to the console
```shell
echo "Incoming connection entries found in MongoDB log file:"

grep "incoming connection" "$LOG_FILE"
```

### Increase the maximum number of allowed connections to accommodate the current traffic or add additional resources to handle the incoming connections.
```shell


#!/bin/bash

# Set the maximum number of connections to ${MAX_CONNECTIONS}

max_connections=${MAX_CONNECTIONS}

# Edit the MongoDB configuration file to set the maximum number of connections

sudo sed -i "s/^maxIncomingConnections.*/maxIncomingConnections: $max_connections/" /etc/mongod.conf

# Restart the MongoDB service to apply the changes

sudo systemctl restart mongod

```


This incident type typically involves a high volume of incoming connections to a MongoDB database, which can cause performance issues and potentially impact the availability of the database. It often requires investigation and remediation to prevent further issues.


This incident type refers to a situation where the Tomcat server's JDBC connection pool usage surpasses its configured limits. This can lead to a shortage of available connections for incoming requests, resulting in slow response times or even server crashes. It is important to monitor and manage the JDBC connection pool usage to prevent such incidents from occurring.


Tomcat High JDBC Connection Pool Usage Incident.

This incident type refers to a situation where Redis, a popular in-memory data structure store, has rejected connections. This could happen due to various reasons such as server overload, network issues, or misconfiguration. When this occurs, it can cause disruptions in the performance of applications that rely on Redis for data storage or caching. Thus, it requires immediate attention and resolution to minimize the impact on the applications and users.


Redis Rejected Connections Incident

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Rabbitmq memory high incident.

This incident type refers to a scenario where there is a high rate of statement timeouts in a Postgresql database instance. This can lead to degraded performance and potentially impact the availability of the database. It is important to quickly identify and address the underlying cause of the timeouts to ensure the stability of the system.


Postgresql high rate statement timeout incident.

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Postgres Connection Limit Reached

```shell
# Environment Variables

export HOST="PLACEHOLDER"

export PORT="PLACEHOLDER"

export PATH_TO_MONGODB_LOG="PLACEHOLDER"

export MAX_CONNECTIONS="PLACEHOLDER"

```


### Check MongoDB connection status

```shell
mongo ${HOST}:${PORT} --eval "db.runCommand({ping:1})"
```

### Check MongoDB connection limit

```shell
mongo ${HOST}:${PORT} --eval "db.runCommand({whatsmyuri:1}).limit"
```

### Check available MongoDB connections

```shell
mongo ${HOST}:${PORT} --eval "db.serverStatus().connections"
```

### Check MongoDB replication status

```shell
mongo ${HOST}:${PORT} --eval "rs.status()"
```

### Check current MongoDB read/write operations

```shell
mongo ${HOST}:${PORT} --eval "db.currentOp()"
```

### Check MongoDB system logs for any errors

```shell
tail -f /var/log/mongodb/mongod.log
```

### Check MongoDB configuration file for connection limits and timeouts

```shell
cat /etc/mongod.conf
```


### Set the path to the MongoDB log file

```shell
LOG_FILE=${PATH_TO_MONGODB_LOG}
```

### Check if the log file exists

```shell
if [ ! -f "$LOG_FILE" ]; then

    echo "MongoDB log file not found."

    exit 1

fi
```

### Search the log file for entries related to incoming connections

```shell
grep "incoming connection" "$LOG_FILE"
```

### If no entries are found, exit with an error message

```shell
if [ $? -ne 0 ]; then

    echo "No incoming connection entries found in MongoDB log file."

    exit 1

fi
```

### If entries are found, print them to the console

```shell
echo "Incoming connection entries found in MongoDB log file:"

grep "incoming connection" "$LOG_FILE"
```

### Increase the maximum number of allowed connections to accommodate the current traffic or add additional resources to handle the incoming connections.

```shell


#!/bin/bash

# Set the maximum number of connections to ${MAX_CONNECTIONS}

max_connections=${MAX_CONNECTIONS}

# Edit the MongoDB configuration file to set the maximum number of connections

sudo sed -i "s/^maxIncomingConnections.*/maxIncomingConnections: $max_connections/" /etc/mongod.conf

# Restart the MongoDB service to apply the changes

sudo systemctl restart mongod

```


High incoming connections on MongoDB

Overview

Parameters

Debug

Check MongoDB connection status

Check MongoDB connection limit

Check available MongoDB connections

Check MongoDB replication status

Check current MongoDB read/write operations

Check MongoDB system logs for any errors

Check MongoDB configuration file for connection limits and timeouts

Repair

Set the path to the MongoDB log file

Check if the log file exists

If no entries are found, exit with an error message

If entries are found, print them to the console

Increase the maximum number of allowed connections to accommodate the current traffic or add additional resources to handle the incoming connections.

Learn more

Related Runbooks

Tomcat High JDBC Connection Pool Usage Incident.

Redis Rejected Connections Incident

Rabbitmq memory high incident.

Postgresql high rate statement timeout incident.

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