---
id: ea7692d4-5121-4ec9-bec6-81c1b760bb88
---

# Cassandra compaction executor blocked tasks.
---

This incident type refers to a situation where some tasks in the Cassandra compaction executor are blocked, impacting the performance of the system. It may occur due to various reasons, such as high resource utilization, hardware failures, or software bugs. This issue needs to be addressed promptly to ensure the smooth functioning of the system.

### Parameters
```shell
# Environment Variables

export PATH_TO_CASSANDRA_LOG="PLACEHOLDER"

export PATH_TO_CASSANDRA_CONFIG="PLACEHOLDER"

export KEYSPACE_NAME="PLACEHOLDER"

export TABLE_NAME="PLACEHOLDER"
```

## Debug

### Check CPU and memory utilization
```shell
top
```

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

### Check if the Cassandra service is running
```shell
systemctl status cassandra
```

### Check Cassandra logs for errors
```shell
tail -f /var/log/cassandra/system.log
```

### Check if compaction is running
```shell
nodetool compactionstats
```

### Check for blocked tasks in compaction
```shell
nodetool tpstats | grep CompactionExecutor | awk '{print $1,$5}'
```

### Configuration issues: Incorrect configuration of the Cassandra cluster or executor can cause tasks to block.
```shell


#!/bin/bash



# Set up variables

cassandraConfig=${PATH_TO_CASSANDRA_CONFIG}

cassandraLog=${PATH_TO_CASSANDRA_LOG}



# Check if Cassandra configuration file exists

if [ ! -f $cassandraConfig/cassandra.yaml ]; then

    echo "Cassandra configuration file not found at $cassandraConfig/cassandra.yaml"

    exit 1

fi



# Check if the Cassandra cluster is running

if ! pgrep -x "cassandra" > /dev/null; then

    echo "Cassandra cluster is not running"

    exit 1

fi



# Check if there are any configuration errors in the log

if grep -q "ERROR" $cassandraLog/system.log; then

    echo "There are configuration errors in the Cassandra log"

    exit 1

fi



# Check if the Cassandra compaction executor is configured correctly

if grep -q "compaction_thread_pool_size" $cassandraConfig/cassandra.yaml; then

    compactionSize=$(grep "compaction_thread_pool_size" $cassandraConfig/cassandra.yaml | awk '{print $2}')

    if [ $compactionSize -lt 2 ]; then

        echo "Compaction thread pool size is too low"

        exit 1

    fi

else

    echo "Compaction thread pool size not found in Cassandra configuration file"

    exit 1

fi



echo "Cassandra cluster is configured correctly"


```

## Repair


### Compact all tables in cassandra database using nodetool utility to force the completion of the blocked compaction task.
```shell
nodetool compact ${KEYSPACE_NAME} ${TABLE_NAME}
```



### Restarting the Cassandra compaction executor can help resolve the issue, as it can clear any stuck tasks and ensure the smooth functioning of the system.
```shell
bash

#!/bin/bash



# Stop the Cassandra compaction executor

sudo service cassandra stop



# Wait for a few seconds to ensure that the service is stopped

sleep 5



# Start the Cassandra compaction executor

sudo service cassandra start



# Check the status of the Cassandra compaction executor

sudo service cassandra status


```

This incident type refers to a situation where some tasks in the Cassandra compaction executor are blocked, impacting the performance of the system. It may occur due to various reasons, such as high resource utilization, hardware failures, or software bugs. This issue needs to be addressed promptly to ensure the smooth functioning of the system.


This incident type refers to a failure in one or more Spark executors during the execution of a job. Spark executors are worker processes that run computations and store data in memory or on disk. When an executor fails, it can cause the entire job to fail or result in degraded performance. This type of incident can occur for a variety of reasons, such as hardware or network issues, memory errors, or software bugs.


Spark executor failure during job execution.

Compaction is a process in Cassandra that merges multiple SSTables (Sorted String Tables) into a single SSTable, eliminating any redundant data and improving read performance. However, sometimes compaction can fail due to various reasons such as insufficient disk space or corrupted data, resulting in degraded performance or even complete failure of the database. Troubleshooting compaction merging SSTables involves identifying and resolving the root cause of such failures to ensure the smooth functioning of the Cassandra database.


Troubleshooting Compaction Merging SSTables in Cassandra

This incident type refers to a situation where there is a significant delay in the execution of queries on a Cassandra cluster. This delay can cause the system to become unresponsive and result in slower performance. It may be caused by a variety of factors such as an increase in traffic, inefficient queries, or hardware issues. The issue can impact the functionality of the system and requires immediate attention to prevent further disruption.


Slow Query Performance on Cassandra Cluster.

In this incident type, there is an issue with a Cassandra cluster where one or more disks are running slow. This can cause performance issues and potentially lead to data loss or downtime. The goal is to identify and address the specific disk(s) causing the problem in order to restore normal cluster operations.


Slow Disk in Cassandra Cluster

Misconfigured compaction strategy is an incident type that occurs when the way data is compacted within a database cluster is not properly configured. This can lead to excessive compaction activity that can negatively impact the cluster's performance and stability. The incident can cause slow query response times, increased disk usage, and high CPU utilization, among other issues. It is crucial to identify and fix the misconfiguration promptly to ensure the cluster's smooth operation.


Misconfigured Compaction Strategy.

```shell
# Environment Variables

export PATH_TO_CASSANDRA_LOG="PLACEHOLDER"

export PATH_TO_CASSANDRA_CONFIG="PLACEHOLDER"

export KEYSPACE_NAME="PLACEHOLDER"

export TABLE_NAME="PLACEHOLDER"
```


### Check CPU and memory utilization

```shell
top
```

### Check disk usage

```shell
df -h
```

### Check if the Cassandra service is running

```shell
systemctl status cassandra
```

### Check Cassandra logs for errors

```shell
tail -f /var/log/cassandra/system.log
```

### Check if compaction is running

```shell
nodetool compactionstats
```

### Check for blocked tasks in compaction

```shell
nodetool tpstats | grep CompactionExecutor | awk '{print $1,$5}'
```

### Configuration issues: Incorrect configuration of the Cassandra cluster or executor can cause tasks to block.

```shell


#!/bin/bash



# Set up variables

cassandraConfig=${PATH_TO_CASSANDRA_CONFIG}

cassandraLog=${PATH_TO_CASSANDRA_LOG}



# Check if Cassandra configuration file exists

if [ ! -f $cassandraConfig/cassandra.yaml ]; then

    echo "Cassandra configuration file not found at $cassandraConfig/cassandra.yaml"

    exit 1

fi



# Check if the Cassandra cluster is running

if ! pgrep -x "cassandra" > /dev/null; then

    echo "Cassandra cluster is not running"

    exit 1

fi



# Check if there are any configuration errors in the log

if grep -q "ERROR" $cassandraLog/system.log; then

    echo "There are configuration errors in the Cassandra log"

    exit 1

fi



# Check if the Cassandra compaction executor is configured correctly

if grep -q "compaction_thread_pool_size" $cassandraConfig/cassandra.yaml; then

    compactionSize=$(grep "compaction_thread_pool_size" $cassandraConfig/cassandra.yaml | awk '{print $2}')

    if [ $compactionSize -lt 2 ]; then

        echo "Compaction thread pool size is too low"

        exit 1

    fi

else

    echo "Compaction thread pool size not found in Cassandra configuration file"

    exit 1

fi



echo "Cassandra cluster is configured correctly"


```


### Compact all tables in cassandra database using nodetool utility to force the completion of the blocked compaction task.

```shell
nodetool compact ${KEYSPACE_NAME} ${TABLE_NAME}
```

### Restarting the Cassandra compaction executor can help resolve the issue, as it can clear any stuck tasks and ensure the smooth functioning of the system.

```shell
bash

#!/bin/bash



# Stop the Cassandra compaction executor

sudo service cassandra stop



# Wait for a few seconds to ensure that the service is stopped

sleep 5



# Start the Cassandra compaction executor

sudo service cassandra start



# Check the status of the Cassandra compaction executor

sudo service cassandra status


```


Cassandra compaction executor blocked tasks.

Overview

Parameters

Debug

Check CPU and memory utilization

Check disk usage

Check if the Cassandra service is running

Check Cassandra logs for errors

Check if compaction is running

Check for blocked tasks in compaction

Configuration issues: Incorrect configuration of the Cassandra cluster or executor can cause tasks to block.

Repair

Compact all tables in cassandra database using nodetool utility to force the completion of the blocked compaction task.

Restarting the Cassandra compaction executor can help resolve the issue, as it can clear any stuck tasks and ensure the smooth functioning of the system.

Learn more

Related Runbooks

Spark executor failure during job execution.

Troubleshooting Compaction Merging SSTables in Cassandra

Slow Query Performance on Cassandra Cluster.

Slow Disk in Cassandra Cluster

Support