Logging will slow the start up of the server. Use logging for debugging only. Recording limit: Though the recording limit for class caching is set to a specific class, you can configure this class in your environment to a different class. WebLogic Server classloading is centered on the concept of an application. An application is normally packaged in an Enterprise Archive EAR file containing application classes. Everything within an EAR file is considered part of the same application.
The following may be part of an EAR or can be loaded as standalone applications:. If you deploy an EJB and a Web application separately, they are considered two applications. If they are deployed together within an EAR file, they are one application. You deploy modules together in an EAR file for them to be considered part of the same application. Every application receives its own classloader hierarchy; the parent of this hierarchy is the system classpath classloader.
This isolates applications so that application A cannot see the classloaders or classes of application B. In hierarchy classloaders, no sibling or friend concepts exist. Application code only has visibility to classes loaded by the classloader associated with the application or module and classes that are loaded by classloaders that are ancestors of the application or module classloader. WebLogic Server automatically creates a hierarchy of classloaders when an application is deployed.
A child classloader is created for each Web application WAR file. This architecture also allows Web applications to be redeployed without redeploying the EJB tier. This concept is discussed in more detail in the next section Application Classloading and Pass-by-Value or Reference. You can create custom classloader hierarchies for an application allowing for better control over class visibility and reloadability. You achieve this by defining a classloader-structure element in the weblogic-application.
The following diagram illustrates how classloaders are organized by default for WebLogic applications. An application level classloader exists where all EJB classes are loaded. For each Web module, there is a separate child classloader for the classes of that module. This hierarchy is optimal for most applications, because it allows call-by-reference semantics when you invoke EJBs. It also allows Web modules to be independently reloaded without affecting other modules.
Further, it allows code running in one of the Web modules to load classes from any of the EJB modules. This is convenient, as it can prevent a Web module from including the interfaces for EJBs that it uses. Note that some of those benefits are not strictly Java EE-compliant. The ability to create custom module classloaders provides a mechanism to declare alternate classloader organizations that allow the following:.
You can declare the classloader hierarchy in the WebLogic-specific application deployment descriptor weblogic-application. The top-level element in weblogic-application. If you do not specify this element, then the standard classloader is used. Also, if you do not include a particular module in the definition, it is assigned a classloader, as in the standard hierarchy. That is, EJB modules are associated with the application root classloader, and Web application modules have their own classloaders.
The classloader-structure element allows for the nesting of classloader-structure stanzas, so that you can describe an arbitrary hierarchy of classloaders. There is currently a limitation of three levels. The outermost entry indicates the application classloader.
For any modules not listed, the standard hierarchy is assumed. The following is an example of a classloader declaration defined in the classloader-structure element in weblogic-application. The organization of the nesting indicates the classloader hierarchy. The above stanza leads to a hierarchy shown in the following diagram.
User-defined classloader restrictions give you better control over what is reloadable and provide inter-module class visibility. This feature is primarily for developers. It is useful for iterative development, but the reloading aspect of this feature is not recommended for production use, because it is possible to corrupt a running application if an update includes invalid elements.
Custom classloader arrangements for namespace separation and class visibility are acceptable for production use. However, programmers should be aware that the Java EE specifications say that applications should not depend on any given classloader organization.
Some classloader hierarchies can cause modules within an application to behave more like modules in two separate applications. For example, if you place an EJB in its own classloader so that it can be reloaded individually, you receive call-by-value semantics rather than the call-by-reference optimization Oracle provides in our standard classloader hierarchy. Also note that if you use a custom hierarchy, you might end up with stale references. Therefore, if you reload an EJB module, you should also reload the calling modules.
There are some restrictions to creating user-defined module classloader hierarchies; these are discussed in the following sections. If you use a custom classloader hierarchy, servlet reloading is disabled for Web applications in that particular application. Nesting is limited to three levels including the application classloader.
Deeper nestings lead to a deployment exception. Thus other modules can invoke an EJB, even though they do not include the interface classes in their own module. This is possible because EJBs are always loaded into the root classloader and all other modules either share that classloader or have a classloader that is a child of that classloader.
With the custom classloader feature, you can configure a classloader hierarchy so that a callee's classes are not visible to the caller. In this case, the calling module must include the interface classes. This is the same requirement that exists when invoking on modules in a separate application. The standard classloader hierarchy provided with WebLogic Server allows for calls between modules within an application to use call-by-reference semantics.
This is because the caller is always using the same classloader or a child classloader of the callee. With this feature, it is possible to configure the classloader hierarchy so that two modules are in separate branches of the classloader tree.
In this case, call-by-value semantics are used. You should use the correct way like below.. When I run the command line, the -d64 option is not recognized. Is there a specific java version I need to use for this? Jay, I have learned a lot from this website, being a newbie to WebLogic. You and your friends are extremely knowledgeable and thanks for providing answers to many people. I have my environment with WebLogic The admin server started crashing with growing heap for no reason.
This was working all fine in WebLogic 9. Should I have to do the whole weblogic installation, with the generic jar file and also install 64 bit JDK separately. Hi Kumar, You are facing very high heap utilization issue at your end…. The bitJVM architecture has many advantages like in tat you can assign a very large heap space as well which is not possible in bit jvm.
So we would recommend you to please enable the Garbage collection logs on your server and then analyze it as mentioned in the following articles … or if you want then you can also provide us a copy of the GC log contact middlewaremagic. For example, wlfullclient.
Nor does wlfullclient. Generate the wlfullclient. Obtain an instance of the service object by performing a lookup using the initial context. This instance can then be used just like a local object reference. Sample code to for a simple WebLogic full client is provided in Example So I threw this bash command-line to accomplish the same thing. Sign up or log in Sign up using Google. Sign up using Facebook. Sign up using Email and Password. Post as a guest Name.
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