Tag Archives: Debugging

Liferay

How to debug Liferay when nothing is printed in logs and there is a problem? – ChatGPT & BARD Generated

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Debugging issues in Liferay when nothing is printed in the logs can be challenging, but there are several strategies you can employ to identify and resolve the problem. Here are some steps to guide you through the debugging process:

### 1. Enable More Verbose Logging

– Action: Adjust the logging level for specific packages or components within Liferay to capture more detailed information. This can be done via the Control Panel under “Server Administration” → “Log Levels”, or by modifying the portal-ext.properties file to include more verbose logging for the suspected components.

– Goal: To capture more detailed logs that might not be visible under normal logging levels, which could provide insights into the underlying issue.

### 2. Use External Debugging Tools

– Action: Connect an external debugger to the Liferay JVM. Most IDEs (like Eclipse, IntelliJ IDEA) allow you to attach a debugger to a remote Java process. You will need to start Liferay with remote debugging enabled by setting appropriate JVM options.

– Goal: To step through the code in real-time to understand the flow and pinpoint where the issue might be occurring.

### 3. Thread Dump Analysis

– Action: If the problem seems related to hanging or performance issues, generate a thread dump from the JVM. This can be done using tools like jstack or from the operating system’s command line.

– Goal: To analyze the state of threads within the JVM and identify any deadlocks, long-waiting threads, or other anomalies that might indicate where the system is getting stuck.

### 4. Memory and Heap Analysis

– Action: Use Java profiling tools (like VisualVM, YourKit, or Eclipse Memory Analyzer) to analyze memory usage and heap dumps. This can help in identifying memory leaks, excessive memory usage, or other memory-related issues.

– Goal: To understand memory allocation and garbage collection patterns which might be affecting the performance or functionality of Liferay.

### 5. Enable Request Tracing

– Action: Utilize Liferay’s built-in request tracing capabilities (if available in your version) or use external tools like browser developer tools or network traffic analyzers to trace the HTTP requests and responses.

– Goal: To understand the flow of requests and responses in the system, helping to identify any failures or bottlenecks in the request processing pipeline.

### 6. Review Front-End Console and Network Activity

– Action: Use the browser’s developer tools to inspect the console for JavaScript errors and the network activity for failed or stalled requests.

– Goal: To catch any client-side issues that might not be apparent on the server side, such as failed AJAX requests, loading errors for resources, or JavaScript execution issues.

### 7. Check External Dependencies

– Action: Ensure that all external systems and services that Liferay depends on (like databases, external APIs, LDAP servers) are operational and accessible.

– Goal: To rule out connectivity issues, authentication failures, or other problems with external dependencies that might cause Liferay to behave unexpectedly.

### 8. Perform A/B Testing

– Action: If possible, compare the behavior on another environment where the issue is not present (e.g., development, staging, or another production environment). This can help identify environmental or configuration differences that might be contributing to the issue.

– Goal: To isolate the problem to either code, configuration, or environment-specific issues.

### 9. Review Recent Changes

– Action: Review any recent changes to the system, including software upgrades, configuration changes, custom developments, or deployed plugins, which might have introduced the issue.

– Goal: To identify if the issue correlates with a specific change, which can then be rolled back or further investigated.

### 10. Consult Community Forums and Support

– Action: Search for similar issues in Liferay community forums, Stack Overflow, or official Liferay support channels. If you have a Liferay subscription, consider opening a support ticket.

– Goal: To leverage collective knowledge and experiences from the Liferay community or get direct support from Liferay experts.

Debugging complex issues in Liferay or any large enterprise platform can be a process of elimination and investigation. Patience, systematic troubleshooting, and leveraging available tools and resources are key to identifying and resolving the problem.

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Here are steps you can take to debug Liferay when there are no logs and a problem persists:

1. Verify Log Configuration:

  • Check Log Levels: Ensure log levels are set to DEBUG for relevant components in portal-log4j-ext.xml.
  • Confirm File Paths: Verify that log files are written to the correct locations and have appropriate permissions.
  • Review Logging Configuration: Ensure logging is enabled in Liferay’s Control Panel (Server Administration -> Log Levels).
  • Disable Custom Filters: If you’ve implemented custom log filters, temporarily disable them to rule out interference.

2. Inspect Server Logs:

  • Examine Server Logs: Check server logs (e.g., Tomcat’s catalina.out) for clues, as some errors might be logged there instead.
  • Analyze Stack Traces: Look for stack traces or error messages that might hint at the issue’s origin.

3. Activate Additional Logging:

  • Enable Finer-Grained Logging: Temporarily increase logging levels for specific classes or packages to capture more detailed information.
  • Utilize Debugging Tools: Employ Java debugging tools (e.g., Eclipse’s debugger) to step through code execution and identify the problem area.

4. Isolate the Issue:

  • Simplify the Scenario: Reproduce the issue in a minimal environment to pinpoint the root cause more easily.
  • Disable Customizations: Temporarily disable custom plugins or themes to see if the problem persists in a standard Liferay configuration.

5. Analyze Browser Developer Tools:

  • Inspect Network Requests: Examine network requests and responses in browser developer tools to identify any failed requests or unusual behavior.
  • Check Console Errors: Look for JavaScript errors or warnings in the browser console that might provide additional insights.

6. Check for Known Issues:

  • Refer to Liferay Documentation: Consult Liferay’s documentation and community forums for similar reported issues and potential solutions.
  • Search for Bug Fixes: Check Liferay’s issue tracker for bug fixes or workarounds related to the problem you’re experiencing.

7. Seek Community Support:

  • Engage with the Community: If you’re still stuck, provide detailed information about your setup, Liferay version, and the specific problem in Liferay community forums or support channels for expert assistance.
Databases, OpenJDK

List of tools for debugging and profiling OpenJDK & Databases – BARD generated – Part 1

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Here’s a list of tools you can use with OpenJDK for debugging and profiling, along with their key features and some visual examples:

Debugging Tools:

  • Java VisualVM:Built-in tool, included with OpenJDK. Monitors memory usage, CPU threads, and garbage collection. Profiles application performance. Captures and analyzes thread dumps. Java VisualVM screenshot: https://docs.oracle.com/javase/8/docs/technotes/guides/visualvm/
  • JDB (Java Debugger):Command-line debugger included with OpenJDK. Sets breakpoints, inspects variables, and steps through code. JDB command-line debugger screenshot: https://www.tutorialspoint.com/jdb/jdb_quick_guide.htm
  • JDWP (Java Debug Wire Protocol):Enables remote debugging with tools like IntelliJ IDEA, Eclipse, NetBeans, and Visual Studio Code. Attaches to running JVM processes.

Profiling Tools:

  • Java Flight Recorder (JFR):Built-in profiling tool in OpenJDK 7 and later. Records low-level JVM events for detailed performance analysis. Visualized using Java Mission Control (JMC). Java Mission Control with Flight Recorder data: https://docs.oracle.com/en/java/java-components/jdk-mission-control/
  • JProfiler:Commercial profiler with advanced features for memory, CPU, threads, and lock analysis. Identifies performance bottlenecks and memory leaks. JProfiler screenshot: https://www.ej-technologies.com/
  • YourKit Java Profiler:Another commercial profiler with similar features to JProfiler. Offers deep code analysis and memory optimization. YourKit Java Profiler screenshot: https://www.yourkit.com/

Additional Tools:

  • JMC (Java Mission Control): Analyzes JFR recordings for troubleshooting and optimization.
  • Async Profiler: Open-source profiler for asynchronous and concurrent applications.
  • BTrace: Dynamic instrumentation tool for runtime analysis without code modification.

Choosing the Right Tool:

The best tool depends on your specific needs and preferences. Consider factors like:

  • Ease of use: Do you prefer a visual interface or command-line tools?
  • Features: What specific debugging or profiling capabilities are you looking for?
  • Integration: Does the tool integrate with your development environment?
  • Cost: Are you willing to pay for a commercial tool, or do you prefer open-source options?

These are all small but powerful command-line tools included in the OpenJDK that can be incredibly useful for debugging and profiling Java applications. They each have their own specific functionality:

jstack:

  • Captures a thread dump of the Java application, showing the state of each thread and what it’s currently doing. This is extremely helpful for diagnosing deadlocks, slowdowns, and other thread-related issues.
  • Example: jstack <pid> – where <pid> is the process ID of your Java application.

jmap:

  • Provides information about the heap memory usage of your application. It can show you the overall memory consumed, how it’s distributed among different object types, and even generate heap dumps for further analysis.
  • Example: jmap -histo <pid> – generates a histogram of object types in the heap.

jhat:

  • Analyzes heap dumps generated by jmap or other tools, allowing you to explore the objects in the heap in detail. You can see how objects are linked together, identify potential memory leaks, and investigate object allocations.
  • Example: jhat <heap_dump_file> – opens the heap dump file in the JHAT graphical user interface.

jstat:

  • Prints various runtime statistics of your Java application, including things like CPU usage, garbage collection activity, and class loading information. This can be helpful for monitoring performance and identifying potential bottlenecks.
  • Example: jstat -gccapacity <pid> – displays the capacities of different generations in the garbage collector.

Here’s a table summarizing the key differences:

Tool Functionality Use Cases

jstack Thread dump capture Diagnose deadlocks, slowdowns, thread issues

jmap Heap memory analysis Investigate memory usage, generate heap dumps

jhat Heap dump analysis Identify memory leaks, analyze object allocations

jstat Runtime statistics Monitor performance, identify bottlenecks

Remember:

  • These tools are command-line based, so some familiarity with the command line is helpful.
  • You can find more information about each tool by running jstack -h, jmap -h, jhat -h, and jstat -h for their respective help manuals.
  • Combining these tools together can be powerful for comprehensive debugging and profiling. For example, you can use jstat to monitor performance, then use jmap to generate a heap dump if you see high memory usage, and then analyze the dump with jhat to identify the cause.

I hope this information helps! Let me know if you have any further questions.

Here are some key tools for RDBMS debugging and profiling, categorized by their functions:

Database-Specific Tools:

  • SQL Server: SQL Server Profiler: Captures events and traces for performance analysis. Database Engine Tuning Advisor: Recommends indexes and statistics for optimization. Extended Events: Advanced tracing framework for detailed monitoring.
  • Oracle: Oracle Enterprise Manager (OEM): Comprehensive monitoring and management console. Automatic Workload Repository (AWR): Collects performance statistics for analysis. SQL Trace and TKPROF: Tools for tracing SQL execution and analyzing performance.
  • MySQL: MySQL Workbench: GUI for managing and profiling MySQL instances. Performance Schema: Built-in instrumentation for collecting performance data. SHOW PROFILE and SHOW STATUS: Statements for viewing query execution details.
  • PostgreSQL: pgAdmin: GUI for managing and profiling PostgreSQL instances. EXPLAIN ANALYZE: Statement for analyzing query execution plans. pg_stat_statements: Extension for tracking execution statistics of SQL statements.

Third-Party Tools:

  • Datadog: Cloud-based monitoring platform for various databases.
  • New Relic: Application performance monitoring with database insights.
  • AppDynamics: Application performance management with database monitoring.
  • Nagios: Open-source monitoring system with database plugins.
  • Zabbix: Open-source monitoring system with database monitoring capabilities.

General-Purpose Tools:

  • Wireshark: Network protocol analyzer for capturing and inspecting database traffic.
  • tcpdump: Command-line tool for capturing network packets, including database traffic.

Key Considerations for Choosing Tools:

  • Database platform: Ensure compatibility with your specific RDBMS.
  • Features: Identify the debugging and profiling capabilities you need.
  • Ease of use: Consider the tool’s interface and learning curve.
  • Integration: Assess how well it integrates with your existing tools and workflows.
  • Cost: Evaluate pricing models for commercial tools versus open-source options.