Menu
If my web application and ejb application are on the same machine (on same JVM) and all the ejb calls are local calls , will the use of ThreadLocal create any issue while passing information from web to ejb?
Any workaround if the ejb calls are remote? Will ThreadLocal information be available from web application to ejb application? Is use of ThreadLocal advisable in such scenario?
992
ThreadLocal is useful, when you want to have some state that should not be shared amongst different threads, but it should be accessible from each thread during its whole lifetime. As an example, imagine a web application, where each request is served by a different thread.
ThreadLocal instances are typically private static fields in classes that wish to associate state with a thread (e.g., a user ID or Transaction ID). For example, the class below generates unique identifiers local to each thread. A thread's id is assigned the first time it invokes ThreadId.
The Java ThreadLocal class enables you to create variables that can only be read and written by the same thread. Thus, even if two threads are executing the same code, and the code has a reference to the same ThreadLocal variable, the two threads cannot see each other's ThreadLocal variables.
Java ThreadLocal class provides thread-local variables. It enables you to create variables that can only be read and write by the same thread. If two threads are executing the same code and that code has a reference to a ThreadLocal variable then the two threads can't see the local variable of each other.
For the first question, there is no problem as long as you remove the ThreadLocal variables at the end of every call. This is important because containers (servlet or ejb) typically use threadpools and therefore reuse threads, this has two effects: one "call" may see threadlocal info coming from a previous call, and if you remove an app from the container without stopping the JVM some classes may not be garbage collected because they are still referenced by a container thread. So put data in a threadlocal in a try / finally block and remove in the finally part.
Here is a post showing one way to handle the problem: ThreadLocal in web applications
For the second question as data is threadlocal it will not come with a remote call, you have to add a parameter to your interfaces, extract threadlocal data on one side and recreate it on the other side...
66
If you love us? You can donate to us via Paypal or buy me a coffee so we can maintain and grow! Thank you!
Donate Us With
