This post explores how threads in Kotlin enter a BLOCKED state when they cannot acquire a lock held by another thread. A sample program demonstrates this scenario with 10 threads attempting to access a synchronized method, causing 9 to be blocked. It also discusses diagnosing BLOCKED threads through manual and automated approaches.
The application connecting to the Oracle RAC cluster experienced performance issues due to resource constraints, causing unresponsiveness. Troubleshooting artifacts were collected and analyzed using yCrash, revealing that 46% of threads were blocked waiting for database responses. After escalating to the DBA, resource adjustments resolved the slowdown, restoring normal application function.
Apache PDFBox is an open-source library for handling PDF documents in Java. A recent deadlock issue was identified in the library, which occurs when two threads are blocked, waiting for resources held by each other. The problem was diagnosed using a thread dump, and a ticket was filed, resulting in a prompt fix by the PDFBox team.
This post discusses deadlock in multi-threaded applications, specifically in Kotlin. It defines deadlock and provides a practical example using trains on a single track. A sample Kotlin program illustrates how deadlock occurs between two threads. Troubleshooting deadlock involves capturing thread dumps and analyzing them with tools like yCrash for clearer insight.
The post discusses troubleshooting intermittent HTTP 502 Bad Gateway errors in an application running on AWS Elastic Beanstalk. The errors were traced to the Tomcat server, which was terminated due to insufficient RAM (1GB). Upgrading to a 2GB RAM EC2 instance resolved the issue, eliminating the errors.
To troubleshoot OutOfMemoryError, follow three steps: capture heap dump using JVM arguments to automate collection when errors occur, restart the application to maintain stability, and diagnose the problem using tools like Eclipse MAT or HeapHero for automated analysis. This approach can streamline the troubleshooting process significantly.