> ## Documentation Index
> Fetch the complete documentation index at: https://docs.activeviam.com/llms.txt
> Use this file to discover all available pages before exploring further.

# Logging overview

## Logback custom converters

Atoti provides three Logback converters you can register in your `logback.xml` to enrich log patterns with server-specific context.

| Converter                                                         | Description                                                                                                                                                                                                     |
| ----------------------------------------------------------------- | --------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| `com.activeviam.tech.logging.logback.spring.api.LogUserConverter` | Displays the current user for the thread (from the security layer or the health event).                                                                                                                         |
| `com.activeviam.tech.logging.logback.api.LogThreadConverter`      | Displays the current thread; useful for health events. Can override the default Logback `%thread`.                                                                                                              |
| `com.activeviam.tech.logging.logback.api.LogInstanceConverter`    | Required only for ELK/JSON-log setups: provides the node instance name (from `atoti.server.node.instance.name`, default `atoti`) so the source node of a log can be identified in a centralized logging system. |

The example below registers all three converters and uses `%thread` and `%user` in an appender pattern.

```xml theme={"languages":{"custom":["/engine/python-sdk/0.9/languages/pycon.tmLanguage.json"]}}
<?xml version="1.0" encoding="UTF-8"?>
{/* Example LOGBACK Configuration File http://logback.qos.ch/manual/configuration.html */}
<configuration>
    <shutdownHook class="ch.qos.logback.core.hook.DelayingShutdownHook"/>
    <jmxConfigurator/>
    {/* Exposing the conversion rules */}
    <conversionRule conversionWord="thread"
                    converterClass="com.activeviam.tech.logging.logback.api.LogThreadConverter"/>
    <conversionRule conversionWord="user"
                    converterClass="com.activeviam.tech.logging.logback.spring.api.LogUserConverter"/>

    <appender name="MAIN" class="ch.qos.logback.core.rolling.RollingFileAppender">
        <file>${custom.log.dir}/${project.artifactId}.log</file>
        <rollingPolicy class="ch.qos.logback.core.rolling.TimeBasedRollingPolicy">
            <fileNamePattern>${custom.log.dir}/${project.artifactId}_%d{yyyy-MM-dd}.log.gz
            </fileNamePattern>
            <maxHistory>30</maxHistory>
            <cleanHistoryOnStart>true</cleanHistoryOnStart>
        </rollingPolicy>

        <encoder>
            {/* Using the converter in the appender pattern layout */}
            <pattern>%d{yyyy-MM-dd HH:mm:ss.SSS} [Thread: %thread; User: %user] %-5level %logger{35} -
                %msg%n
            </pattern>
        </encoder>
    </appender>
    [...]
    <root level="INFO">
        <appender-ref ref="MAIN"/>
    </root>
    <contextListener class="ch.qos.logback.classic.jul.LevelChangePropagator">
        <resetJUL>true</resetJUL>
    </contextListener>
</configuration>
```

## Blocked-thread watchdog

The blocked-thread watchdog is an opt-in component that periodically scans for blocked JVM threads.
When it detects a change in the blocked-thread count, it logs a summary on the `atoti.server.monitoring.health` logger and writes a full thread dump on the `atoti.server.monitoring.health.blocked-thread` logger.

The watchdog is disabled by default because a full thread dump is verbose. Enable it only when you need to diagnose lock contention.

| Property                                                       | Default | Description                                                                        |
| -------------------------------------------------------------- | ------- | ---------------------------------------------------------------------------------- |
| `atoti.server.monitoring.blockedThreadWatchdog.enabled`        | `false` | Set to `true` to activate the watchdog.                                            |
| `atoti.server.monitoring.blockedThreadWatchdog.scanIntervalMs` | `60000` | Interval in milliseconds between scans. Only applies when the watchdog is enabled. |

## Loggers per modules

Check the logger documentation of the component you want to monitor:

* [Datastore](../datastore/datastore_monitoring)
* [DirectQuery](../directquery/directquery_monitoring#logging)
* [Distribution](../distributed/distribution_monitoring#logging)
* [Source](../sources/source_monitoring)

## Composer loggers (Atoti Technical Modules)

There are loggers available in the Atoti generic technical modules.
They are used in a lot of places in Atoti Server.

Here is the exhaustive list of the loggers available in the Atoti Composer:

* atoti.server.tech
  * atoti.server.tech.aggregation
  * atoti.server.tech.arrow
  * atoti.server.tech.bitmap
  * atoti.server.tech.chunks
    * atoti.server.tech.chunks.allocation
    * atoti.server.tech.chunks.compression
    * atoti.server.tech.chunks.creation
  * atoti.server.tech.code-generation
  * atoti.server.tech.concurrency
    * atoti.server.tech.concurrency.fence
    * atoti.server.tech.concurrency.numa
    * atoti.server.tech.concurrency.stop-watch
    * atoti.server.tech.concurrency.threads
  * atoti.server.tech.condition
  * atoti.server.tech.dictionary
  * atoti.server.tech.formatter
  * atoti.server.tech.jdbc
  * atoti.server.tech.jmx
  * atoti.server.tech.memory
  * atoti.server.tech.mvcc
  * atoti.server.tech.observability
    * atoti.server.tech.observability.health-event
  * atoti.server.tech.partitioning
  * atoti.server.tech.property
  * atoti.server.tech.records
  * atoti.server.tech.registry
  * atoti.server.tech.timings
  * atoti.server.tech.utilities
  * atoti.server.tech.vector