---
id: 69556277-33cd-4770-8eb3-87c57384f0f5
---

# High CPU and Keep-Alive Connections in Apache Server
---

This incident type refers to a high resource utilization issue in an Apache server. Specifically, it involves a high number of keep-alive async connections combined with high CPU usage. The recommended solution involves lowering the maximum number of simultaneous connections to the server and/or decreasing the KeepAliveTimeout to avoid holding connections open longer than necessary. This incident type can impact the performance of the Apache server and may require immediate attention to avoid further issues.

### Parameters
```shell
# Environment Variables

export APACHE_CONFIG_FILE="PLACEHOLDER"

export NEW_MAX_WORKERS_VALUE="PLACEHOLDER"

export KEEP_ALIVE_THRESHOLD="PLACEHOLDER"

export CPU_THRESHOLD="PLACEHOLDER"

export PATH_TO_APACHE_CONF_FILE="PLACEHOLDER"
```

## Debug

### Display the current cpu usage using the 'top' command.
```shell
top
```

### Check Apache processes
```shell
ps aux | grep apache
```

### Check Apache resource usage
```shell
apachectl fullstatus | grep "CPU usage\|requests currently being processed"
```

### Check Apache configuration
```shell
apachectl -t -D DUMP_VHOSTS
```

### Check Apache error log for any recent errors
```shell
tail -n 50 /var/log/apache2/error.log
```

### Check Apache access log for requests and response codes
```shell
tail -n 50 /var/log/apache2/access.log
```

### Check the current number of established connections
```shell
netstat -anp | grep 80 | grep ESTABLISHED | wc -l
```

### Check the maximum number of simultaneous connections allowed
```shell
grep "MaxRequestWorkers" ${APACHE_CONFIG_FILE}
```

### Check the KeepAliveTimeout setting
```shell
grep "KeepAliveTimeout" ${APACHE_CONFIG_FILE}
```

### A sudden increase in traffic to the server could lead to a spike in CPU usage and the number of Keep-Alive connections.
```shell


#!/bin/bash



# Get the current CPU usage

cpu_usage=$(top -b -n1 | grep "Cpu(s)" | awk '{print $2 + $4}')



# Get the current number of Keep-Alive connections

keep_alive_connections=$(netstat -an | grep ":80" | awk '{print $6}' | sort | uniq -c | sort -n | grep "WAIT" | awk '{print $1}')



# Check if the CPU usage or number of Keep-Alive connections exceeds a certain threshold

if (( $(echo "$cpu_usage > ${CPU_THRESHOLD}" | bc -l) )) || (( $(echo "$keep_alive_connections > ${KEEP_ALIVE_THRESHOLD}" | bc -l) )); then

    echo "Warning: High CPU usage or Keep-Alive connections detected."

    # Add any additional diagnostic commands or actions here

fi


```

## Repair

### Set the desired MaxRequestWorkers value
```shell
max_workers=${NEW_MAX_WORKERS_VALUE}
```

### Set the Apache configuration file path
```shell
apache_conf=/etc/httpd/conf/httpd.conf
```

### Find the current MaxRequestWorkers line and replace its value
```shell
sed -i "s/^\s*MaxRequestWorkers\s*[0-9]\+/MaxRequestWorkers $max_workers/" $apache_conf
```

### Restart the Apache service
```shell
systemctl restart httpd.service
```

### Decrease the KeepAliveTimeout to avoid holding connections open longer than necessary.
```shell


#!/bin/bash



# Set the new KeepAliveTimeout value

NEW_TIMEOUT=5



# Locate the Apache configuration file

CONF_FILE=${PATH_TO_APACHE_CONF_FILE}



# Check if the configuration file exists

if [ ! -f "$CONF_FILE" ]; then

    echo "Error: Apache configuration file not found."

    exit 1

fi



# Backup the original configuration file

cp "$CONF_FILE" "$CONF_FILE.bak"



# Replace the current KeepAliveTimeout value with the new one

sed -i "s/KeepAliveTimeout [0-9]\+/KeepAliveTimeout $NEW_TIMEOUT/" "$CONF_FILE"



# Restart Apache to apply the changes

service apache2 restart



echo "KeepAliveTimeout value updated to $NEW_TIMEOUT seconds."


```


This incident type refers to a high resource utilization issue in an Apache server. Specifically, it involves a high number of keep-alive async connections combined with high CPU usage. The recommended solution involves lowering the maximum number of simultaneous connections to the server and/or decreasing the KeepAliveTimeout to avoid holding connections open longer than necessary. This incident type can impact the performance of the Apache server and may require immediate attention to avoid further issues.


This incident occurs when the Tomcat server is experiencing an unusually high number of active sessions. Active sessions refer to the number of users currently accessing a web application hosted on the Tomcat server. When the number of active sessions exceeds the server's capacity, it can lead to slow response times, unresponsive applications, or even server crashes. This incident requires immediate attention to resolve the issue and prevent any further impact on the web application's performance.


Tomcat High Number of Active Sessions.

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 typically refers to a situation where there is an anomaly in the Tomcat max processing time on a host. The maximum amount of time it takes for the server to process one request, from the time an available thread starts processing the request to the time it returns a response, has exceeded the expected threshold. This could indicate that a JSP page isn’t loading or an associated process (such as a database query) is taking too long to complete.


Anomalous max processing time for Tomcat host

This incident type occurs when the number of concurrent connections to a MySQL database server exceeds the configured limit of 80%. This can lead to performance degradation or even database server crashes, making the application or system that relies on the database server unavailable for the end-users. This type of incident typically requires immediate attention and resolution to restore normal operation of the affected service.


MySQL too many connections incident

A high CPU load incident occurs when the CPU usage of a host or server exceeds a certain threshold, typically 80%. This can cause slowdowns, unresponsiveness, or even crashes in the affected system. It is critical to address this issue promptly to minimize impact on users and prevent further damage to the system.


High CPU Load Incident

```shell
# Environment Variables

export APACHE_CONFIG_FILE="PLACEHOLDER"

export NEW_MAX_WORKERS_VALUE="PLACEHOLDER"

export KEEP_ALIVE_THRESHOLD="PLACEHOLDER"

export CPU_THRESHOLD="PLACEHOLDER"

export PATH_TO_APACHE_CONF_FILE="PLACEHOLDER"
```


### Display the current cpu usage using the 'top' command.

```shell
top
```

### Check Apache processes

```shell
ps aux | grep apache
```

### Check Apache resource usage

```shell
apachectl fullstatus | grep "CPU usage\|requests currently being processed"
```

### Check Apache configuration

```shell
apachectl -t -D DUMP_VHOSTS
```

### Check Apache error log for any recent errors

```shell
tail -n 50 /var/log/apache2/error.log
```

### Check Apache access log for requests and response codes

```shell
tail -n 50 /var/log/apache2/access.log
```

### Check the current number of established connections

```shell
netstat -anp | grep 80 | grep ESTABLISHED | wc -l
```

### Check the maximum number of simultaneous connections allowed

```shell
grep "MaxRequestWorkers" ${APACHE_CONFIG_FILE}
```

### Check the KeepAliveTimeout setting

```shell
grep "KeepAliveTimeout" ${APACHE_CONFIG_FILE}
```

### A sudden increase in traffic to the server could lead to a spike in CPU usage and the number of Keep-Alive connections.

```shell


#!/bin/bash



# Get the current CPU usage

cpu_usage=$(top -b -n1 | grep "Cpu(s)" | awk '{print $2 + $4}')



# Get the current number of Keep-Alive connections

keep_alive_connections=$(netstat -an | grep ":80" | awk '{print $6}' | sort | uniq -c | sort -n | grep "WAIT" | awk '{print $1}')



# Check if the CPU usage or number of Keep-Alive connections exceeds a certain threshold

if (( $(echo "$cpu_usage > ${CPU_THRESHOLD}" | bc -l) )) || (( $(echo "$keep_alive_connections > ${KEEP_ALIVE_THRESHOLD}" | bc -l) )); then

    echo "Warning: High CPU usage or Keep-Alive connections detected."

    # Add any additional diagnostic commands or actions here

fi


```


### Set the desired MaxRequestWorkers value

```shell
max_workers=${NEW_MAX_WORKERS_VALUE}
```

### Set the Apache configuration file path

```shell
apache_conf=/etc/httpd/conf/httpd.conf
```

### Find the current MaxRequestWorkers line and replace its value

```shell
sed -i "s/^\s*MaxRequestWorkers\s*[0-9]\+/MaxRequestWorkers $max_workers/" $apache_conf
```

### Restart the Apache service

```shell
systemctl restart httpd.service
```

### Decrease the KeepAliveTimeout to avoid holding connections open longer than necessary.

```shell


#!/bin/bash



# Set the new KeepAliveTimeout value

NEW_TIMEOUT=5



# Locate the Apache configuration file

CONF_FILE=${PATH_TO_APACHE_CONF_FILE}



# Check if the configuration file exists

if [ ! -f "$CONF_FILE" ]; then

    echo "Error: Apache configuration file not found."

    exit 1

fi



# Backup the original configuration file

cp "$CONF_FILE" "$CONF_FILE.bak"



# Replace the current KeepAliveTimeout value with the new one

sed -i "s/KeepAliveTimeout [0-9]\+/KeepAliveTimeout $NEW_TIMEOUT/" "$CONF_FILE"



# Restart Apache to apply the changes

service apache2 restart



echo "KeepAliveTimeout value updated to $NEW_TIMEOUT seconds."


```


High CPU and Keep-Alive Connections in Apache Server

Overview

Parameters

Debug

Display the current cpu usage using the 'top' command.

Check Apache processes

Check Apache resource usage

Check Apache configuration

Check Apache error log for any recent errors

Check Apache access log for requests and response codes

Check the current number of established connections

Check the maximum number of simultaneous connections allowed

Check the KeepAliveTimeout setting

A sudden increase in traffic to the server could lead to a spike in CPU usage and the number of Keep-Alive connections.

Repair

Set the desired MaxRequestWorkers value

Set the Apache configuration file path

Find the current MaxRequestWorkers line and replace its value

Restart the Apache service

Decrease the KeepAliveTimeout to avoid holding connections open longer than necessary.

Learn more

Related Runbooks

Tomcat High Number of Active Sessions.

Tomcat High JDBC Connection Pool Usage Incident.

Anomalous max processing time for Tomcat host

MySQL too many connections incident

Support