---
id: a21ccf4e-9e93-4f06-aee0-9598c7176062
---

# Frequent Tomcat Thread Pauses
---

Tomcat Thread Pauses is a type of incident that occurs when the Tomcat server experiences frequent pauses in its threads. This can cause delay in server response time and may lead to application downtime. This issue can be caused by a variety of factors such as incorrect configuration, excessive load on the server, or memory leaks in the application code. It is important to investigate and resolve this issue promptly to ensure smooth functioning of the application.

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

export TOMCAT_LOG_FILE="PLACEHOLDER"

export NEW_MEMORY_SIZE="PLACEHOLDER"

export PATH_TO_TOMCAT_DIRECTORY="PLACEHOLDER"
```

## Debug

### Get the process ID of the Tomcat instance
```shell
TOMCAT_PID=$(pgrep -f ${TOMCAT_PROCESS_NAME})
```

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

### Check if there are any errors or warnings in the Tomcat logs
```shell
tail -f ${TOMCAT_LOG_FILE}
```

### Check the status of the Tomcat threads
```shell
jstack $TOMCAT_PID
```

### Check the number of open file descriptors by the Tomcat process
```shell
lsof -p $TOMCAT_PID | wc -l
```

### Check the network connections of the Tomcat process
```shell
netstat -nap | grep $TOMCAT_PID
```

## Repair

### Increase the memory allocation of the JVM to ensure that there is enough memory available for the Tomcat server to run efficiently.
```shell


#!/bin/bash



# set the path to the Tomcat installation directory

TOMCAT_DIR=${PATH_TO_TOMCAT_DIRECTORY}



# set the new memory allocation size

NEW_MEM_SIZE=${NEW_MEMORY_SIZE}



# stop the Tomcat server

$TOMCAT_DIR/bin/shutdown.sh



# set the new memory allocation size in the Tomcat startup script

sed -i "s/-Xmx[0-9]*[mMgG]/-Xmx$NEW_MEM_SIZE/g" $TOMCAT_DIR/bin/startup.sh



# start the Tomcat server

$TOMCAT_DIR/bin/startup.sh


```

Tomcat Thread Pauses is a type of incident that occurs when the Tomcat server experiences frequent pauses in its threads. This can cause delay in server response time and may lead to application downtime. This issue can be caused by a variety of factors such as incorrect configuration, excessive load on the server, or memory leaks in the application code. It is important to investigate and resolve this issue promptly to ensure smooth functioning of the application.


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_PROCESS_NAME="PLACEHOLDER"

export TOMCAT_LOG_FILE="PLACEHOLDER"

export NEW_MEMORY_SIZE="PLACEHOLDER"

export PATH_TO_TOMCAT_DIRECTORY="PLACEHOLDER"
```


### Get the process ID of the Tomcat instance

```shell
TOMCAT_PID=$(pgrep -f ${TOMCAT_PROCESS_NAME})
```

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

```shell
top -p $TOMCAT_PID
```

### Check if there are any errors or warnings in the Tomcat logs

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

### Check the status of the Tomcat threads

```shell
jstack $TOMCAT_PID
```

### Check the number of open file descriptors by the Tomcat process

```shell
lsof -p $TOMCAT_PID | wc -l
```

### Check the network connections of the Tomcat process

```shell
netstat -nap | grep $TOMCAT_PID
```


### Increase the memory allocation of the JVM to ensure that there is enough memory available for the Tomcat server to run efficiently.

```shell


#!/bin/bash



# set the path to the Tomcat installation directory

TOMCAT_DIR=${PATH_TO_TOMCAT_DIRECTORY}



# set the new memory allocation size

NEW_MEM_SIZE=${NEW_MEMORY_SIZE}



# stop the Tomcat server

$TOMCAT_DIR/bin/shutdown.sh



# set the new memory allocation size in the Tomcat startup script

sed -i "s/-Xmx[0-9]*[mMgG]/-Xmx$NEW_MEM_SIZE/g" $TOMCAT_DIR/bin/startup.sh



# start the Tomcat server

$TOMCAT_DIR/bin/startup.sh


```


Frequent Tomcat Thread Pauses

Overview

Parameters

Debug

Get the process ID of the Tomcat instance

Check the CPU and memory usage of the Tomcat process

Check if there are any errors or warnings in the Tomcat logs

Check the status of the Tomcat threads

Check the number of open file descriptors by the Tomcat process

Check the network connections of the Tomcat process

Repair

Increase the memory allocation of the JVM to ensure that there is enough memory available for the Tomcat server to run efficiently.

Learn more

Related Runbooks

Tomcat thread pool exhaustion.

Tomcat Servlet Session Replication Failures.

Tomcat Server Crash

Tomcat PermGen or Metaspace Usage exceeds 90%

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