I have a long running Java process running in CentOs Machine. I have both info and error logs set-up properly. The process ran for longer time (18+ hours) and disappeared all of a sudden. There is no trace of error/exception (OutOfMemoryError/ OutOfDiskSpace Error). How to figure out what has really happened, as in why and how the process got killed?
These are the OS details. CentOS release 5.11 (Final) Kernel \r on an \m
Are there any standard system logs or commands to figure out? This job is running in a servlet in Tomcat. Tomcat is also going down mysteriously.
Your process is mostly likely killed because the system runs out of memory. When it happens it first tries to kill short-running processes instead of long running ones. OOM Killer is unlikely to be logged in your application logs.
dmesg and try to find there info about killing
Here is how “badness” of a tasj to kill determined in Linux https://www.kernel.org/doc/gorman/html/understand/understand016.html#toc21 :
badness_for_task = total_vm_for_task / (sqrt(cpu_time_in_seconds) * sqrt(sqrt(cpu_time_in_minutes)))
Kernel steps through all running tasks.
OpenJDk or Open Java Development Kit is a free, open-source framework of the Java Platform, Standard Edition (or Java SE). It contains the virtual machine, the Java Class Library, and the Java compiler. The difference between the Oracle OpenJDK and Oracle JDK is that OpenJDK is a source code reference point for the open-source model. Simultaneously, the Oracle JDK is a continuation or advanced model of the OpenJDK, which is not open source and requires a license to use.
In this article, we will be installing OpenJDK on Centos 8.
#tutorials #alternatives #centos #centos 8 #configuration #dnf #frameworks #java #java development kit #java ee #java environment variables #java framework #java jdk #java jre #java platform #java sdk #java se #jdk #jre #open java development kit #open source #openjdk #openjdk 11 #openjdk 8 #openjdk runtime environment
According to some surveys, such as JetBrains’s great survey, Java 8 is currently the most used version of Java, despite being a 2014 release.
What you are reading is one in a series of articles titled ‘Going beyond Java 8,’ inspired by the contents of my book, Java for Aliens. These articles will guide you step-by-step through the most important features introduced to the language, starting from version 9. The aim is to make you aware of how important it is to move forward from Java 8, explaining the enormous advantages that the latest versions of the language offer.
In this article, we will talk about the most important new feature introduced with Java 10. Officially called local variable type inference, this feature is better known as the **introduction of the word **
var. Despite the complicated name, it is actually quite a simple feature to use. However, some observations need to be made before we can see the impact that the introduction of the word
var has on other pre-existing characteristics.
#java #java 11 #java 10 #java 12 #var #java 14 #java 13 #java 15 #verbosity
Logstash is a free, open source, server-side data collection and processing engine which uses dynamic pipelining capabilities. It takes in information from multiple data sources, reconstructs it, and then sends it to a destination of our choice. Logstash also cleans and modifies the data for use in an advanced outbound analytics and visualization use cases. It is the L in the ELK stack (Elasticsearch, Logstash and Kibana) and is typically responsible for sending data to Elasticsearch.
Effectively administrating Linux systems requires familiarity with the locations of and possible contents of logs. Application and system-level logs provide insight into an application’s behavior or the system that might not be apparent on the surface. When many cooperating systems each provide their logs, aggregating, and processing that information becomes imperative. This is where Logstash shines.
#tutorials #apt transport https #data filters #data pipeline #data processing #elasticsearch #elk #event pipeline #java #java jdk #kibana #log collector #log collectors #log files #logs #logstash #ubuntu #ubuntu 18.04
On March 16th, 2021, Java 16 was GA. With this new release, tons of new exciting features have been added. Check out the release notes to know more about these changes in detail. This article’s focus will be on Java Records, which got delivered with JEP 395. Records were first introduced in JDK 14 as a preview feature proposed by JEP 359, and with JDK 15, they remained in preview with JEP 384. However, with JDK 16, Records are no longer in preview.
I have picked Records because they are definitely the most favored feature added in Java 16, according to this Twitter poll by Java Champion Mala Gupta.
I also conducted a similar survey, but it was focused on features from Java 8 onwards. The results were not unexpected, as Java 8 is still widely used. Very unfortunate, though, as tons of new features and improvements are added to newer Java versions. But in terms of features, Java 8 was definitely a game-changer from a developer perspective.
So let’s discuss what the fuss is about Java Records.
#java #springboot #java programming #records #java tutorials #java programmer #java records #java 16
Java is not the hardest language to start with. So, it becomes way popular among novice developers joining the ranks of Java coders every single day. If you are reading this blog post, you might be interested in learning Java.
Java is widely used across industry, and especially in the area of Enterprise software, which results in many high paying job opportunities and makes this programming language a common language for newbies. A general promotion of it within colleges and other institutions providing a formal Computer Science education also contributes to its popularity.
However, these are not the only advantages of Java — among other things, it allows you to adopt good practices and makes it way easier to learn other languages in the future. And with no doubt, you can easily learn it if you’re following the right approach. In this post, I am going to share some of them with you.
Beyond all doubt, practice is important and valuable. But, before we get to the advantages of hands-on experience, I want to draw your attention to one essential thing I often tell my students.
New programmers who are just learning and start implementing things, without being supervised, often end up adapting bad practices. To avoid that, especially when you are making your first steps in programming, I recommend looking for a person who will supervise you and teach you. A strong mentorship with someone engaged in a serious project, as well as communication within the community in the form of sharing code and asking for feedback, is worth the effort. Similarly, when you are applying for your first job, you want to be looking for a company with a strong team and a good leader who would be keen on investing into your learning.
Now, let’s return to practical experience. Learning by doing is different from learning by passively consuming the information. To make sure we can use all the newly acquired technology, we should put our skills to test and write tons of code. The benefits of hands-on experience are almost endless.
By practicing, you get a clear understanding of what programming is. Consequently, you start doing better with each new hands-on task, complete it faster, and thus become more productive.
Even if you are not working on real-world projects yet, it’s important to get used to having deadlines. They are inextricably linked to the programming process. My recommendation is to set up your own deadlines while practicing stage and follow them as closely as possible.
#java #learn java #java code #learn java in easy way #learn java course #learn java development