---
id: cc1eb769-74ff-406a-bf47-79e937d5f34f
---

# Tomcat Frequent Full GC Events
---

Tomcat is a widely used open source web server and servlet container software. Full GC (Garbage Collection) is a process that runs in Java Virtual Machine (JVM) to reclaim memory occupied by objects that are no longer in use. When Full GC events happen too frequently, it can cause performance issues and lead to application downtime. This incident type refers to the occurrence of frequent Full GC events in Tomcat.

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

export TOMCAT_LOG_FILE="PLACEHOLDER"

export NEW_HEAP_SIZE="PLACEHOLDER"

export PATH_TO_TOMCAT="PLACEHOLDER"
```

## Debug

### Check the system load
```shell
uptime
```

### Check memory usage
```shell
free -m
```

### Check swap usage
```shell
swapon -s
```

### Check disk usage
```shell
df -h
```

### Monitor the Java heap usage in real-time
```shell
jmap -histo ${TOMCAT_PID}
```

### Check the Tomcat log files for errors
```shell
tail -f ${TOMCAT_LOG_FILE}
```

### Get a thread dump of the Tomcat process
```shell
jstack ${TOMCAT_PID}
```

### Check the Java heap usage and GC statistics
```shell
jstat -gc ${TOMCAT_PID}
```

## Repair

### Increase the heap size of Tomcat to mitigate frequent full garbage collection events.
```shell
bash

#!/bin/bash



# Define variables

TOMCAT_HOME=${PATH_TO_TOMCAT}

HEAP_SIZE=${NEW_HEAP_SIZE}



# Stop Tomcat service

sudo systemctl stop tomcat



# Set new heap size

sed -i "s/-Xmx[0-9]*m/-Xmx${HEAP_SIZE}m/" $TOMCAT_HOME/bin/catalina.sh



# Start Tomcat service

sudo systemctl start tomcat


```

Tomcat is a widely used open source web server and servlet container software. Full GC (Garbage Collection) is a process that runs in Java Virtual Machine (JVM) to reclaim memory occupied by objects that are no longer in use. When Full GC events happen too frequently, it can cause performance issues and lead to application downtime. This incident type refers to the occurrence of frequent Full GC events in Tomcat.


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 Servlet Session Replication Failures occur when a Tomcat server fails to replicate session data between instances. This can result in users losing their session data or being redirected to a different instance, causing disruption to the application's functionality.


Tomcat Servlet Session Replication Failures.

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

```shell
export TOMCAT_PID="PLACEHOLDER"

export TOMCAT_LOG_FILE="PLACEHOLDER"

export NEW_HEAP_SIZE="PLACEHOLDER"

export PATH_TO_TOMCAT="PLACEHOLDER"
```


### Check the system load

```shell
uptime
```

### Check memory usage

```shell
free -m
```

### Check swap usage

```shell
swapon -s
```

### Check disk usage

```shell
df -h
```

### Monitor the Java heap usage in real-time

```shell
jmap -histo ${TOMCAT_PID}
```

### Check the Tomcat log files for errors

```shell
tail -f ${TOMCAT_LOG_FILE}
```

### Get a thread dump of the Tomcat process

```shell
jstack ${TOMCAT_PID}
```

### Check the Java heap usage and GC statistics

```shell
jstat -gc ${TOMCAT_PID}
```


### Increase the heap size of Tomcat to mitigate frequent full garbage collection events.

```shell
bash

#!/bin/bash



# Define variables

TOMCAT_HOME=${PATH_TO_TOMCAT}

HEAP_SIZE=${NEW_HEAP_SIZE}



# Stop Tomcat service

sudo systemctl stop tomcat



# Set new heap size

sed -i "s/-Xmx[0-9]*m/-Xmx${HEAP_SIZE}m/" $TOMCAT_HOME/bin/catalina.sh



# Start Tomcat service

sudo systemctl start tomcat


```


Tomcat Frequent Full GC Events

Overview

Parameters

Debug

Check the system load

Check memory usage

Check swap usage

Check disk usage

Monitor the Java heap usage in real-time

Check the Tomcat log files for errors

Get a thread dump of the Tomcat process

Check the Java heap usage and GC statistics

Repair

Increase the heap size of Tomcat to mitigate frequent full garbage collection events.

Learn more

Related Runbooks

Tomcat thread pool exhaustion.

Tomcat Servlet Session Replication Failures.

Tomcat Server Crash

Tomcat PermGen or Metaspace Usage exceeds 90%

Support