jaespeak.blogg.se - Hypack tutorial

At the same time thread B needs resource X which is blocked by thread A. To identify the root cause of the deadlock, a thread dump is required.Įxample: Let’s consider a scenario in which thread A holds a resource X and needs resource Y which is blocked by thread B.

Deadlock:ĭeadlock is a situation when two or more threads are waiting for the other threads to complete their tasks in order to complete their own tasks. But the problem occurs when two or more threads utilize the same resources and leads deadlock situation. Java is a multi-threaded application that allows multiple thread execution at any particular time. A web server uses tens to hundreds of threads to process a large number of concurrent users and achieve multithreading.

Threads allow different tasks to be performed concurrently.

Cost of thread intercommunication is relatively low than that of process intercommunication.

Context switching between threads is usually less expensive than between processes.

Threads share the same address space and therefore can share both data and code.

A thread is lightweight and faster than a process.

Some of the basic features of a Thread are: Threads help to allow multiple activities within a single process and act like lightweight processes. Each thread has a unique identifier, name, and category.

All the Java threads are managed by JVM (Java Virtual Machine) which are mapped with operating system thread, also called as Native Thread. Thread:Ī thread is a series of statements which can be processed in parallel in the same program to achieve the concurrency. Are some threads stuck in deadlock? Are all the threads running? Which threads are waiting for the blocked resources etc? All these questions can be answered by analysing in the thread dump.īefore jumping on to Thread dump, firstly I would like to introduce you with some basic terms which are helpful to understand the concept of Thread Dump: 1. Thread Dump helps to find out what every thread in the JVM is doing at a particular point in time. Thread dumps are vital artefacts to diagnose CPU spikes, deadlocks, poor response times, memory problems, unresponsive applications and other system problems. Similar to Heap Dump, Thread Dump is a snapshot of the status of all the threads at a particular time. Now, let’s move further and try to understand what is the thread dump and how it can be analysed? We have already discussed Heap Dump and its analysis in the previous post. Dumping is a well-known term in the performance testing, whether it is heap dump or thread dump both are very useful to carry out the root cause analysis.