What is class loader WebSphere?
The WebSphere extensions class loader loads the WebSphere Application Server classes that are required at run time. WebSphere Application Server classes are provided as a set of OSGi bundles. Each bundle is loaded by a separate class loader within a network of OSGi class loaders.
What is thread dump in WebSphere application server?
As a WebSphere administrator, you should be aware of taking thread dumps and tools to analyze them. Thread dumps are often needed to diagnose the application performance issue like deadlocks, hung threads, and bottlenecks in Java threads.
How do I enable verbose class loading in WebSphere?
In the Server Infrastructure section, open Java and Process Management and select Process Definition. Under Additional Properties, select Java Virtual Machine. Check the Verbose class loading checkbox. Click OK.
What is difference between heap dump and thread dump?
A thread dump is a dump of the stacks of all live threads. Thus useful for analysing what an app is up to at some point in time, and if done at intervals handy in diagnosing some kinds of ‘execution’ problems (e.g. thread deadlock). A heap dump is a dump of the state of the Java heap memory.
Why heap dump is generated in WebSphere?
Although heap dumps are generated only in response to a detected memory leak, you must understand that generating heap dumps can have a severe performance impact on WebSphere Application Server for several minutes.
What is Java core dump in WebSphere?
A javacore file is a snapshot of a running Java process. The IBM Java SDK produces a javacore in response to specific operating system signals. Javacore files show the state of every thread in the Java process, as well as the monitor information identifying Java synchronization locks.
How many class loaders are present in JVM explain?
three class loaders
When the JVM is started, three class loaders are used: Bootstrap class loader. Extensions class loader. System class loader.
How are classes loaded by JVM?
In order to actually load a class, the JVM uses Classloader objects. Every already loaded class contains a reference to its class loader, and that class loader is used to load all the classes referenced from that class.
What are the different class loaders used by JVM?
When the JVM is started, three class loaders are used:
- Bootstrap class loader.
- Extensions class loader.
- System class loader.
What is meant by class loader?
The Java Class Loader is a part of the Java Runtime Environment that dynamically loads Java classes into the Java Virtual Machine. Usually classes are only loaded on demand. The Java run time system does not need to know about files and file systems as this is delegated to the class loader.
What is heap dump and thread dump in WebSphere?
What is heap dump used for?
A heap dump is a snapshot of all the objects in the Java Virtual Machine (JVM) heap at a certain point in time. The JVM software allocates memory for objects from the heap for all class instances and arrays.
What is the use of WebSphere extensions class loader?
The WebSphere extensions class loader loads the WebSphere Application Server classes that are required at run time. WebSphere Application Server classes are provided as a set of OSGi bundles. Each bundle is loaded by a separate class loader within a network of OSGi class loaders.
How do I resolve a classloader exception in WebSphere?
Make sure the classloader exception is generated in the WebSphere logs (SystemOut.log) and the trace file (trace.log). Run the collector tool against the problem profile.
What is the difference between web module class loader and application class loader?
By default, web module class loaders load the contents of the WEB-INF/classes and WEB-INF/lib directories. The application class loader is the parent of the web module class loader. You can change the default behavior by changing the web application archive (WAR) class-loader policy of the application.
What is the default War class loader for a web application?
By default, web modules have their own WAR class loader to load the contents of the WEB-INF/classes and WEB-INF/lib directories. The default WAR class loader value is Class loader for each WAR file in application, which uses a separate class loader to load each WAR file.