---
id: 94e751a3-0cb7-4f49-a627-8a9b211bede5
---

# Tomcat High JDBC Connection Pool Usage Incident.
---

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.

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

export CONNECTION_POOL_CLASS="PLACEHOLDER"

export DATABASE_PORT="PLACEHOLDER"

export THREAD_CLASS="PLACEHOLDER"

export TOMCAT_PORT="PLACEHOLDER"

export POOL_SIZE="PLACEHOLDER"
```

## Debug

### Get the PID of the Tomcat process
```shell
PID=$(pgrep -f ${TOMCAT})
```

### Check the JDBC connection pool usage
```shell
 jmap -histo:live $PID | grep ${CONNECTION_POOL_CLASS}
```

### Check the database connections in use
```shell
 lsof -n -i -P | grep ${DATABASE_PORT}
```

### Check the number of threads in use
```shell
 jstack $PID | grep -c ${THREAD_CLASS}
```

### Check the Tomcat logs for errors
```shell
sudo tail -n 100 /var/log/tomcat//catalina.out | grep -i "error"
```

### Check the CPU and memory usage of the Tomcat process
```shell
top -p $PID
```

### Check the network connections in use
```shell
netstat -anp | grep ${TOMCAT_PORT}
```

### Check the system logs for errors
```shell
sudo tail -n 100 /var/log/messages | grep -i "error"
```

## Repair

### Increase the maximum size of the connection pool to allow for more simultaneous connections.
```shell


#!/bin/bash



# Assign the ${POOL_SIZE} parameter to a variable

pool_size=${POOL_SIZE}



# Navigate to the Tomcat directory

cd /opt/tomcat/



# Access the Tomcat configuration file

config_file=conf/server.xml



# Update the connection pool settings

sed -i "s/maxActive=\"[0-9]\+\"/maxActive=\"$pool_size\"/" $config_file



# Restart Tomcat to apply the changes

systemctl restart tomcat


```

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.


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 TOMCAT="PLACEHOLDER"

export CONNECTION_POOL_CLASS="PLACEHOLDER"

export DATABASE_PORT="PLACEHOLDER"

export THREAD_CLASS="PLACEHOLDER"

export TOMCAT_PORT="PLACEHOLDER"

export POOL_SIZE="PLACEHOLDER"
```


### Get the PID of the Tomcat process

```shell
PID=$(pgrep -f ${TOMCAT})
```

### Check the JDBC connection pool usage

```shell
 jmap -histo:live $PID | grep ${CONNECTION_POOL_CLASS}
```

### Check the database connections in use

```shell
 lsof -n -i -P | grep ${DATABASE_PORT}
```

### Check the number of threads in use

```shell
 jstack $PID | grep -c ${THREAD_CLASS}
```

### Check the Tomcat logs for errors

```shell
sudo tail -n 100 /var/log/tomcat//catalina.out | grep -i "error"
```

### Check the CPU and memory usage of the Tomcat process

```shell
top -p $PID
```

### Check the network connections in use

```shell
netstat -anp | grep ${TOMCAT_PORT}
```

### Check the system logs for errors

```shell
sudo tail -n 100 /var/log/messages | grep -i "error"
```


### Increase the maximum size of the connection pool to allow for more simultaneous connections.

```shell


#!/bin/bash



# Assign the ${POOL_SIZE} parameter to a variable

pool_size=${POOL_SIZE}



# Navigate to the Tomcat directory

cd /opt/tomcat/



# Access the Tomcat configuration file

config_file=conf/server.xml



# Update the connection pool settings

sed -i "s/maxActive=\"[0-9]\+\"/maxActive=\"$pool_size\"/" $config_file



# Restart Tomcat to apply the changes

systemctl restart tomcat


```


Tomcat High JDBC Connection Pool Usage Incident.

Overview

Parameters

Debug

Get the PID of the Tomcat process

Check the JDBC connection pool usage

Check the database connections in use

Check the number of threads in use

Check the Tomcat logs for errors

Check the CPU and memory usage of the Tomcat process

Check the network connections in use

Check the system logs for errors

Repair

Increase the maximum size of the connection pool to allow for more simultaneous connections.

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