The "java.lang.OutOfMemoryError: unable to create new native thread" occurs when an application cannot create new threads due to memory constraints or exceeding operating system limits. Solutions include adjusting thread creation rates, increasing thread limits, allocating more memory, reducing heap space, minimizing processes, and managing thread stack size.
Thread dumps are essential for diagnosing various system issues, including CPU spikes and memory problems. The article outlines nine methods to capture thread dumps, such as using yCrash script, jstack, kill -3, JVisualVM, JMC, and jcmd, emphasizing that yCrash, jstack, kill -3, and jcmd are particularly effective and user-friendly.
I was surprised to witness the Java Executor behavior – which caused “java.lang.OutOfMemoryError: unable to create new native thread” in our application. I would like to share my surprise (i.e. problem) and resolution to it.
The application using DataStax's Java driver to connect with Apache Cassandra faced a 'java.lang.OutOfMemoryError' due to an excessive number of runnable threads, linked to the netty library. This issue arose when Cassandra ran out of space, highlighting the need for client applications to handle such scenarios more resiliently without resulting in OutOfMemoryError.
The article outlines strategies for troubleshooting CPU spikes in Java applications, highlighting issues like repeated Full GC, non-terminating loops, and non-synchronized access to HashMap. It presents tactical and strategic solutions, including monitoring garbage collection, analyzing thread dumps, and replacing HashMap with ConcurrentHashMap to mitigate CPU performance issues.