simply about difficult
Let’s say we need to terminate Spring Boot Yarn application due to checked exception. To do this, in the AppMaster class (it must be specified in the appmaster-class property in application.yml) we need to call the method in the place we need: If you need to stop the application from outside the AppMaster class, you can […]
READ MORELet’s imagine that we have a task: And the code for its execution: And we need to get the return value after completing the task. For this, Runnable must be replaced with Callable: And when sending a task to an ExecutorService, you need to use submit method instead of execute, and capture a Future<Object> object:
READ MORELet’s imagine we have a gRPC service: We are writing a unit test or integration test, and we need to make a test stub for this service. Let’s use Mockito. The code we write below can be used in any way. You can even use it in pure Java. Let’s connect the dependencies to the project: Now, let’s mock […]
READ MORELet’s say you need to run the distcp command: But as a result, you get an error like this: One of the non-obvious reasons for such an error may be that node1:8020 is not an active node. Recheck the hostname and run the command again.
READ MOREThe error looks like this: To solve the problem, you need to update the bytebuddy version to 1.9.3: If the version update did not fix the error, you need to find the correct version of the dependency. Instructions are here: https://mchesnavsky.tech/determine-versions-of-dependencies-of-library-maven/
READ MOREImagine you need to determine the version of Apache commons-lang dependency in ZooKeeper 3.6.2. The easiest way to do this is to find the artifact page in the mvn repository. For ZooKeeper 3.6.2: https://mvnrepository.com/artifact/org.apache.zookeeper/zookeeper/3.6.2. On the page, you need to find the Compile Dependencies section, and find the required dependency there. In our case, the commons-lang 2.6 dependency […]
READ MORELet’s imagine that we need to pass data between the interceptor and the service (or we need to sharedata between the interceptor and the service, or we need to exchange data between the interceptor and the service). We have a service: We have the code for starting the gRPC server: In your Interceptor class, in […]
READ MORELet’s imagine that we need to get the client’s ip address from the request. We have a service: And the code for starting the gRPC server: Let’s create a new class: And register a new interceptor in the gRPC server launch code: Done. If you need to pass the ip address from the interceptor to the […]
READ MOREWhen you try to execute the mvn deploy command, you may encounter the error: The error could actually means (thanks to randomsimon): That is, maven cannot find the repository at the specified url. Check, that the url of the repository is correct, and in general it exists and specified. A repository url can be specified via […]
READ MOREThe documentation states that setting an ACL via the ZooKeeper CLI usually works like this: In the case of the x509 scheme, the Authenticated ID for the user is the DN string of their certificate. In confirmation of this, when a user connects via a certificate, there is a line in the server log: Now, […]
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