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Troubleshoot SDK Components and Operations - Mule 4

The following troubleshooting features are available starting from Mule SDK 1.4.

To troubleshoot Java SDK, learn how to enable logging (including verbose logging) and how to interpret common error messages.

Logging

Use logging to troubleshoot the following SDK components:

Component Name Logging Capabilities

Source

Logs information about the source lifecycle, such as when the lifecycle starts and ends. In case of error and reconnection, the log provides the full stack trace associated with the raised exception. For cluster environments, the log provides source status information, which indicates whether it is the primary source or not.

Polling Source

Logs information about items accepted and rejected by the source. In the case of rejection, the log contains information about the cause of the rejection.

Polling Source Watermarking

Logs information about watermarking handling on polling sources. Because this process uses low-level logic, enable trace logging only when debugging or troubleshooting is necessary.

Pooling Connection Provider

Logs information about connection management for pooling connection providers. This log provides connection pool status information as well as connection handling, which indicates when the pool retrieves and returns connections.

Verbose Logging

Use verbose logging to troubleshoot SDK components to get information regarding their status or behavior. Because of the high impact to application performance, limit verbose logging to testing and troubleshooting operations.

Enable verbose logging in Anypoint Studio, or Anypoint Runtime Manager if using CloudHub APIs. In both cases, the application’s log file logs the information.

Enable Verbose Logging in Anypoint Studio

The following steps describe how to enable verbose logging using Anypoint Studio:

  1. Access Anypoint Studio and navigate to the Package Explorer view.

  2. Open your application’s project name.

  3. Open the src/main/resources path folder.

  4. Open the log4j2.xml file inside the folder.

    Folder structure of the log4j2 xml file

  5. Add an <AsyncLogger> tag inside the <Loggers> tag:

    <Loggers>
    ...
    <AsyncLogger name="<component's fully qualified name>" level="<logging level>"/>
    ...
</Loggers>

    Use the following table as a reference for specifying the component’s fully qualified name:

    Name Fully Qualified Name Log Level

    Source

    org.mule.runtime.module.extension.internal.runtime.source.ExtensionMessageSource

    DEBUG

    Polling Source

    org.mule.runtime.module.extension.internal.runtime.source.poll.PollingSourceWrapper

    DEBUG

    Polling Source Watermarking

    org.mule.runtime.module.extension.internal.runtime.source.poll.PollingSourceWrapper

    TRACE

    Pooling Connection Provider

    org.mule.runtime.core.internal.connection.PoolingConnectionHandler org.mule.runtime.core.internal.connection.PoolingConnectionManagementStrategy

    DEBUG

    The following example shows how to add a fully qualified name to the log4j2.xml file to enable verbose logging for Source:

    <Loggers>
   ...
    <!-- Mule logger -->
    <AsyncLogger name="org.mule.runtime.core.internal.processor.LoggerMessageProcessor" level="INFO"/>
    <AsyncLogger name="org.mule.runtime.module.extension.internal.runtime.source.ExtensionMessageSource" level="DEBUG"/>
    <AsyncRoot level="INFO">
        <AppenderRef ref="file" />
    </AsyncRoot>
</Loggers>

Enable Verbose Logging in Anypoint Runtime Manager

The following steps describe how to enable verbose logging using Anypoint Runtime Manager:

  1. Access Anypoint Runtime Manager.

  2. Select the desired application.

  3. Go to Settings on the left pane.

  4. Go to the Logging tab.

    Logging tab in Runtime Manager

  5. Add the component’s fully qualified name and the logging level (DEBUG or TRACE). Refer to the table that shows how to specify the component’s fully qualified name.

  6. Click Apply Changes.

Logging Examples

The following examples show expected logs for SDK components:

The logs in these examples are from a Mule application that consists of an FTP Connector source that lists files in an FTP server and a logger that logs the name of the file it processes.

Mule flow in Studio that shows FTP Connector source and Logger

Source Logging Example

The following example shows logs for Source:

org.mule.runtime.module.extension.internal.runtime.source.ExtensionMessageSource: Message source 'listener' on flow 'ftp-troubleshooting-examples' threw exception. Attempting to reconnect...
org.mule.runtime.module.extension.internal.runtime.source.ExtensionMessageSource: Message source 'listener' on flow 'ftp-troubleshooting-examples' successfully reconnected
org.mule.runtime.module.extension.internal.runtime.source.ExtensionMessageSource: Message source 'listener' on flow 'ftp-troubleshooting-examples' could not be reconnected. Will be shutdown.
org.mule.runtime.module.extension.internal.runtime.source.ExtensionMessageSource: Message source 'listener' on flow 'ftp-troubleshooting-examples' is stopping

Polling Source Logging Example

The following example shows logs for Polling Source:

org.mule.runtime.module.extension.internal.runtime.source.poll.PollingSourceWrapper: Item with id:[/ftp-example.json] is accepted
org.mule.runtime.module.extension.internal.runtime.source.poll.PollingSourceWrapper: Item with id:[/ftp-example.json] is rejected with status:[FILTERED_BY_WATERMARK]

Polling Source Watermarking Logging Example

The following example shows logs for Polling Source Watermarking:

org.mule.runtime.module.extension.internal.runtime.source.poll.PollingSourceWrapper: A new watermark maximum has been found when processing item with id /ftp-example.json for source in flow ftp-troubleshooting-examples

Pooling Connection Provider Logging Example

The following example shows logs for Pooling Connection Provider:

org.mule.runtime.core.internal.connection.PoolingConnectionManagementStrategy: Acquiring connection org.mule.extension.ftp.internal.connection.FtpFileSystem@1a0c776f from the pool FTP_Config-5e20b7d9-417d-4307-ab4c-9ef3e7ae4d9b
org.mule.runtime.core.internal.connection.PoolingConnectionManagementStrategy: Status for pool FTP_Config-5e20b7d9-417d-4307-ab4c-9ef3e7ae4d9b: 1 connections are active out of 5 max active limit, 0 connections are idle out of 5 max idle limit

Error: Cannot Find org.mule.sdk.api Classes

Java SDK throws errors such as Cannot access XYZ class file: XYZ not found or Cannot find symbol: method someMethod() location: variable someVar of type XYZ, in which XYZ is a class from the org.mule.sdk.api package, when using version 1.4.0 of the module’s parent POM:

<parent>
  <groupId>org.mule.extensions</groupId>
  <artifactId>mule-modules-parent</artifactId>
  <version>1.4.0</version>
</parent>

For example:

[ERROR] Failed to execute goal org.apache.maven.plugins:maven-compiler-plugin:3.8.1:compile (default-compile) on project : Compilation failure:

cannot access org.mule.sdk.api.runtime.streaming.StreamingHelper
[ERROR] class file for org.mule.sdk.api.runtime.streaming.StreamingHelper not found

cannot find symbol
[ERROR]   symbol:   method resolveCursors(java.util.HashMap<java.lang.String,java.lang.Object>,boolean)
[ERROR]   location: variable streamingHelper of type org.mule.runtime.extension.api.runtime.streaming.StreamingHelper

The org.mule.sdk.api package is an experimental feature still under active development. Do not use this package unless it is explicitly instructed by a non-experimental feature documentation page. Since this package is experimental, MuleSoft does not guarantee support or backward compatibility on any class defined in the package.

You should also consider that the classes and interfaces in the org.mule.sdk.api package are not necessarily recognized by all Mule versions. More precisely, none of the org.mule.sdk.api classes are recognized by Mule versions earlier than 4.4, and not all of its components are supported in Mule 4.4 and later.

To fix this error, avoid using the org.mule.sdk.api package and use an equivalent class or annotation from the org.mule.runtime.extension.api package instead.

See Also