---
id: 67acf70e-cc9a-4c4e-a92a-94039b4c71f0
---

# Tomcat High Swap Usage Incident
---

Tomcat High Swap Usage Incident refers to an event where Tomcat, a popular open-source web server, is experiencing high swap usage. Swap usage is a memory management technique used by the operating system to temporarily move data from RAM to the hard disk. When Tomcat is consuming high swap memory, it can cause the server to slow down or even crash, resulting in downtime for the website or application hosted on the server. This incident type requires immediate attention to identify the root cause and resolve the issue to prevent further downtime.

### Parameters
```shell
export PATH_TO_TOMCAT_LOG_FILES="PLACEHOLDER"

export PATH_TO_TOMCAT_CONFIGURATION_FILES="PLACEHOLDER"

export TOMCAT_PORT_NUMBER="PLACEHOLDER"

export PATH_TO_TOMCAT_CONFIG_FILE="PLACEHOLDER"

export DESIRED_HEAP_SIZE="PLACEHOLDER"
```

## Debug

### Check swap usage
```shell
free -h
```

### Check which processes are using the most swap space
```shell
sudo swapon --show --bytes | awk '{print $1}' | xargs -n 1 sudo swapstat -p | sort -k3 -n -r | head -n 10
```

### Check which processes are consuming the most memory
```shell
ps -eo pid,ppid,%mem,%cpu,cmd --sort=-%mem | head -n 11
```

### Check the Tomcat log files for any errors or warnings
```shell
sudo tail -f ${PATH_TO_TOMCAT_LOG_FILES}
```

### Check the Tomcat configuration files for any misconfigurations
```shell
sudo cat ${PATH_TO_TOMCAT_CONFIGURATION_FILES}
```

### Check the Tomcat server status
```shell
sudo systemctl status tomcat
```

### Check the system resource usage
```shell
top
```

### Check network connections to the Tomcat server
```shell
sudo netstat -tulpn | grep ${TOMCAT_PORT_NUMBER}
```

### Check if any other services or applications are consuming high resources
```shell
sudo top
```

## Repair

### Review the Tomcat server configuration settings to ensure that the JVM heap size is optimized correctly.
```shell


#!/bin/bash



# Set the path to the Tomcat configuration file

TOMCAT_CONFIG=${PATH_TO_TOMCAT_CONFIG_FILE}



# Set the desired heap size

HEAP_SIZE=${DESIRED_HEAP_SIZE}



# Backup the original configuration file

cp $TOMCAT_CONFIG $TOMCAT_CONFIG.bak



# Edit the configuration file to set the heap size

sed -i "s/-Xmx[0-9]*[mMgG]/-Xmx${HEAP_SIZE}/g" $TOMCAT_CONFIG



# Restart Tomcat to apply the new configuration

systemctl restart tomcat


```

### Restart the Tomcat server to clear the swap memory usage.
```shell


#!/bin/bash



# Stop the Tomcat server

sudo systemctl stop tomcat.service



# Wait for 10 seconds to ensure the server has stopped

sleep 10



# Clear the swap memory usage

sudo swapoff -a && sudo swapon -a



# Start the Tomcat server

sudo systemctl start tomcat.service


```

Tomcat High Swap Usage Incident refers to an event where Tomcat, a popular open-source web server, is experiencing high swap usage. Swap usage is a memory management technique used by the operating system to temporarily move data from RAM to the hard disk. When Tomcat is consuming high swap memory, it can cause the server to slow down or even crash, resulting in downtime for the website or application hosted on the server. This incident type requires immediate attention to identify the root cause and resolve the issue to prevent further downtime.


When too many requests are sent to a Tomcat server, the thread pools that handle these requests can run out of available threads. This means that incoming requests will not be processed, leading to service degradation or even a complete outage. This incident type is critical for web applications that rely on Tomcat as their application server.


Tomcat thread pool exhaustion.

Tomcat Server Crash incident type refers to a situation where the Tomcat Server, an open-source web server and servlet container, becomes unresponsive and stops functioning. This can result in a complete or partial system outage, leading to a disruption in the delivery of web applications and services. The root cause of the crash can be attributed to a variety of factors such as misconfiguration, network or hardware issues, software bugs, or excessive server load. It is critical to address this incident quickly to minimize the impact on users and restore normal system functionality.


Tomcat Server Crash

This incident type occurs when the PermGen or Metaspace usage of the Tomcat server exceeds 90%. PermGen and Metaspace are memory pools used for storing class definitions and metadata of the Java virtual machine (JVM). When these memory pools reach their maximum capacity, the server may experience performance issues or even crash. This incident requires immediate attention from the software engineer to investigate the root cause and take appropriate actions to resolve the issue.


Tomcat PermGen or Metaspace Usage exceeds 90%

This incident type is related to the Tomcat server, which is a popular open-source Java application server. It occurs when the available threads in the connection pool are running low, which means that there are not enough resources to serve incoming requests. This can cause delays or even failures in the application's performance, impacting the end-user experience. It is important to monitor and address this issue promptly to ensure that the application runs smoothly and efficiently.


Tomcat Low Available Threads in Connection Pool

In software engineering, a large number of suspended threads in Tomcat is an incident type that occurs when a high number of threads are created but are blocked from executing. This can happen due to a variety of reasons, such as slow database queries, network latency, or resource contention. When this occurs, the system may become unresponsive or slow, causing a degradation in performance or even a complete system failure. It is important to investigate and resolve this issue as quickly as possible to ensure the system can continue to function properly.


Tomcat Large Number of Suspended Threads Incident.

```shell
export PATH_TO_TOMCAT_LOG_FILES="PLACEHOLDER"

export PATH_TO_TOMCAT_CONFIGURATION_FILES="PLACEHOLDER"

export TOMCAT_PORT_NUMBER="PLACEHOLDER"

export PATH_TO_TOMCAT_CONFIG_FILE="PLACEHOLDER"

export DESIRED_HEAP_SIZE="PLACEHOLDER"
```


### Check swap usage

```shell
free -h
```

### Check which processes are using the most swap space

```shell
sudo swapon --show --bytes | awk '{print $1}' | xargs -n 1 sudo swapstat -p | sort -k3 -n -r | head -n 10
```

### Check which processes are consuming the most memory

```shell
ps -eo pid,ppid,%mem,%cpu,cmd --sort=-%mem | head -n 11
```

### Check the Tomcat log files for any errors or warnings

```shell
sudo tail -f ${PATH_TO_TOMCAT_LOG_FILES}
```

### Check the Tomcat configuration files for any misconfigurations

```shell
sudo cat ${PATH_TO_TOMCAT_CONFIGURATION_FILES}
```

### Check the Tomcat server status

```shell
sudo systemctl status tomcat
```

### Check the system resource usage

```shell
top
```

### Check network connections to the Tomcat server

```shell
sudo netstat -tulpn | grep ${TOMCAT_PORT_NUMBER}
```

### Check if any other services or applications are consuming high resources

```shell
sudo top
```


### Review the Tomcat server configuration settings to ensure that the JVM heap size is optimized correctly.

```shell


#!/bin/bash



# Set the path to the Tomcat configuration file

TOMCAT_CONFIG=${PATH_TO_TOMCAT_CONFIG_FILE}



# Set the desired heap size

HEAP_SIZE=${DESIRED_HEAP_SIZE}



# Backup the original configuration file

cp $TOMCAT_CONFIG $TOMCAT_CONFIG.bak



# Edit the configuration file to set the heap size

sed -i "s/-Xmx[0-9]*[mMgG]/-Xmx${HEAP_SIZE}/g" $TOMCAT_CONFIG



# Restart Tomcat to apply the new configuration

systemctl restart tomcat


```

### Restart the Tomcat server to clear the swap memory usage.

```shell


#!/bin/bash



# Stop the Tomcat server

sudo systemctl stop tomcat.service



# Wait for 10 seconds to ensure the server has stopped

sleep 10



# Clear the swap memory usage

sudo swapoff -a && sudo swapon -a



# Start the Tomcat server

sudo systemctl start tomcat.service


```


Tomcat High Swap Usage Incident

Overview

Parameters

Debug

Check swap usage

Check which processes are using the most swap space

Check which processes are consuming the most memory

Check the Tomcat log files for any errors or warnings

Check the Tomcat configuration files for any misconfigurations

Check the Tomcat server status

Check the system resource usage

Check network connections to the Tomcat server

Check if any other services or applications are consuming high resources

Repair

Review the Tomcat server configuration settings to ensure that the JVM heap size is optimized correctly.

Restart the Tomcat server to clear the swap memory usage.

Learn more

Related Runbooks

Tomcat thread pool exhaustion.

Tomcat Server Crash

Tomcat PermGen or Metaspace Usage exceeds 90%

Tomcat Low Available Threads in Connection Pool

Support