springboot | spring boot demonstration | Application Framework library

SpringBoot v2.5.1

There is an endpoint requesting a long running process result and it is created somehow
(for simplicity it is Mono.fromCallable( ... long running ... ).

Client make a request and triggers the publisher to do the work, but after several seconds client aborts the request (i.e. connection is lost). And the process still continues to utilize resources for computation of a result to throw away.

What is a mechanism of notifying Project Reactor's event loop about unnecessary work in progress that should be cancelled?

I have a Springboot project and I know I can send a application.properties file as a argument, but is this possible using a jar file?

I built my jar file using maven and in my application I have this piece of code that runs the programm if the user sent the argument run.

Is there any method that allows me to set the application properties if I receive it through argument? Or does the override of the file happens automatically as it does when I use the command mvn spring-boot:run -Dspring.config.location=your.properties

There is a Java 11 (SpringBoot 2.5.1) application with simple workflow:

1. Upload archives (as multipart files with size 50-100 Mb each)
2. Unpack them in memory
3. Send each unpacked file as a message to a queue via JMS

When I run the app locally java -jar app.jar its memory usage (in VisualVM) looks like a saw: high peaks (~ 400 Mb) over a stable baseline (~ 100 Mb).

When I run the same app in a Docker container memory consumption grows up to 700 Mb and higher until an OutOfMemoryError. It appears that GC does not work at all. Even when memory options are present (java -Xms400m -Xmx400m -jar app.jar) the container seems to completely ignore them still consuming much more memory.

So the behavior in the container and in OS are dramatically different. I tried this Docker image in DockerDesktop Windows 10 and in OpenShift 4.6 and got two similar pictures for the memory usage.

Dockerfile

I have used Embedded Redis for caching in my springboot application. The redis runs on localhost and default port "6379" on application start up.

Is there a way to get metrics(memory-used, keyspace_hits, keyspace_misses, etc..) for embedded redis, from outside the application, may be command line or any API?

PS: I have used Redisson as client to perform cache operations with redis.

Thanks.

I'm trying to provide CloseableHttpClient to Spring Cloud OpenFeign. Spring Cloud Open Feign Documentationsays it supports CloeableHttpClient. Spring documentation doesn't give any example of actually replacing the HTTP client.

Basically, I'm providing SSLContext to the HTTP client and I want Feign to use this SSLContext loaded client. How to inject this CloseableHttpClient into the Feign?

Following is my relevant configuration:

1. I'm using SpringBootApp

This is now fixed with SpringBoot 2.5.1

Small question about a warning I am receiving please.

After the release of 2.5.0 of SpringBoot, I just did a version bump from 2.4.x to 2.5.0, without any code change.

Suddenly, on application start up, I am getting

kground-preinit] o.s.h.c.j.Jackson2ObjectMapperBuilder: For Jackson Kotlin classes support please add "com.fasterxml.jackson.module:jackson-module-kotlin" to the classpath

The thing is, my Springboot all is not a Kotlin app, it is a Java app.

It has nothing Kotlin.

Furthermore, I am not even doing any explicit JSON parsing.

May I ask how I can disable, resolve this warning please?

I am working on an application which has 2 modules.

1. server module which is SpringBoot.
2. ui which is in Angular

I am unable to run any E2E tests for my application as it is not starting before the tests run. I have below defined in the test class which should bring up the application context but it seems it does not.

I'm a beginner with spring and I have this little issue. "No property questionId found for type CourseTestCompleteField!" I have 2 model classes that are connected via a one to one join. That 2 model class are:

I have got a Spring Boot project with two data sources, one DB2 and one Postgres. I configured that, but have a problem:

The auto-detection for the database type does not work on the DB2 (in any project) unless I specify the database dialect using spring.jpa.database-platform = org.hibernate.dialect.DB2390Dialect.

But how do I specify that for only one of the database connections? Or how do I specify the other one independently?

Additional info to give you more info on my project structure: I seperated the databases roughly according to this tutorial, although I do not use the ChainedTransactionManager: https://medium.com/preplaced/distributed-transaction-management-for-multiple-databases-with-springboot-jpa-and-hibernate-cde4e1b298e4 I use the same basic project structure and almost unchanged configuration files.