Ktor creates an extra Java process - java

I am working on a KTor server. I run the generated jar file using java -jar command. So I expect that only one Java process should run. After running for a while another Java process is being created which is bound to different port.
I checked the details of the process using ps -a [PID] and find this new Java process is "kotlin-compiler-embeddable" program.
I am wondering why this process is being created, what is use of this and is it safe to kill it.
Thanks for any pointer.

kotlin-compiler-embeddable is used in scenarios when you have to package the compiler in a single jar, and no external dependencies. This is the case of Ktor.

Related

Running Java program in a Docker Image

So I have a Docker network that has a Docker file with a bunch of information. I have a java program that is going to bring up the enviorment and then produce several commands to run within this enviorment. To be clear, the first command I need to run is NOT inside the Docker enviorment. I am having some challenges with the Process and Runtime classes.
First, say I wanted my java program to launch a new gnome terminal and then run a command to get into the docker network. I have this command,
Process process = Runtime.getRuntime().exec(new String[]{"gnome-terminal"});
Gnome terminal sucessfully comes up but any additional arguments I give in this array are just ignored. For example,
Process process = Runtime.getRuntime().exec(new String[]{"gnome-terminal","ls"});
Does not work. The command I ultimatly want to run would look something like this,
Process process = Runtime.getRuntime().exec(new String[]{"gnome-terminal","sudo","docker","exec","-it","sawtooth-shell-default", "bash"});
Second, Once I have this running, will additional commmands I run work within the Docker enviorment? I have a python file with a Stream handler that specifies the correct commands to run.
Other documentation on related issues was limited.
I made sure my code was wrapped in a runtime exception try catch and that I was running the correct .class file. Any help on this would be great!
Edit: I have also tried to run this in another linux terminal like Hyper and Tilda
I also am able to get a sudo sign in when I run the command like so,
Process process = Runtime.getRuntime().exec(new String[]{"gnome-terminal","--","sudo","docker","exec","-it","sawtooth-shell-default", "bash"});
However it closes immediatly after authorizing.
Okay this is what I was attempting to do.
https://www.atlassian.com/blog/software-teams/deploy-java-apps-with-docker-awesome
This site is outdated and I had to use this link for getting that latest version of the java PPA.
This process basically installs java into the docker contatiner so that I can run a java program that uses Runtime.

how to run kubectl command in java

I can run kubectl get secret/rabbitmq-expressmode -n expressmode in shell successfully.
However when I try to run it in java with either ProcessBuilder or Runtime.getRuntime().exec, the error:
Error from server (BadRequest): the server rejected our request for an unknown reason
is thrown out.
What's the possible reason?
Best approach would be to use official java client library.
Installation is pretty easy, and code examples shows you how to use it.
If the official one does not meet your requirements, there are also community-maintained client libraries:
Java (OSGi)
Java (Fabric8, OSGi)
Java
I had same issue but resolved by programmatically creating bash file containing kubectl... command I was trying to execute directly.
For example, create bash file and put your kubectl command there (i.e.: some-file.sh). Then try then executing it in bash process running within your java code (bash some-file.sh).

What is the difference between running by creating a process and running through command line?

I have a jar file. I am running this jar file by creating a process. So, what is the difference between running it through command prompt without creating a process? Will it affect the application's performance?
If your application requires you to run the jar file as a command in a separate process from your java application,It's the way to go.There is no question of performance.
However when you launch command prompt through Runtime.exec(),command line will be executed as a sub-process or a separate process in a random layer.
I'd rather recommend you to use ProcessBuilder,however it's a different topic.
For difference between Runtime.exec() and ProcessBulilder please go through this

using javaw to run jars in batch files results in more than one java processes in process explorer - XYNTService

I have a somewhat strange issue. I have a java application that installs few services that run as Jars. Previously I used installed Java to run these Jars. There are four services and all will be instantiated from a single batch file with sequential call to each other. Something like this,
start %JAVA_HOME% commandtoruntjarfile
would work and all four services will run in the background and only one java.exe visible in process explorer. So I had another service installed as windows service which would start stop these services by calling the run bat or shutdown bat.
Now the customer requirement changed to using an internalized version of java. I extract java to a location, make our own environment variable name "ABC_HOME" and the required syntax in batch changes to
%ABC_HOME%\javaw commandtorunjarfile
When its run it works. but there is no stopping these. When I go to process explorer I see 4 java.exe running each for the four run commands in the batch file. If I stop the windows service all the four keep working. If I restart the windows service the number of java.exe in process explorer goes to eight and keeps going up until windows has had enough of it.
How do I get around it? I think the solution should be to have the one java process in process explorer but I cant seem to find any solution for that.
[EDIT]
The four sub services are actually XYNT processes. In the normal scenario it would be something like this
[Process1]
CommandLine = java -Xrs -DasService=yes -cp jarfiles
WorkingDir = c: bin scache
PauseStart = 1000
PauseEnd = 1000
UserInterface = No
Restart = Yes
For using java from a specific location the following change was needed
CommandLine = %JAVA_PATH%\bin\java.exe -Xrs -DasService=yes -cp jarfiles
but this wouldn't work as it would not accept the path variable in XYNT.ini file. so I called a batch file here and in that batch file I used the above code. So here is what the change looks like,
CommandLine = batchfile.bat
and in batchfile.bat
%JAVA_PATH%\bin\java.exe -Xrs -DasService=yes -cp jarfiles
Usually, every Java program run on your system has its own virtual machine running, which means: one java.exe/javaw.exe per instance of your program.
I can not tell why it "worked" from your point of view with java.exe like you described first, but the behaviour you described for javaw.exe (having 4 java processes in the process explorer) would be what I'd have expected.
For me the question is not why you're seeing 4 vs. 1 java processes, but how you can start/stop the "services". Killing the Java VM externally doesn't seem a very good solution. I'd consider building some IPC into the Java services that allow you to gracefully terminate the processes.

Java running as a Unix service [duplicate]

This question already has answers here:
How to Daemonize a Java Program?
(11 answers)
Closed 7 years ago.
I have built a little daemon in Java and I would like to run it as a service under Unix (e.g. Debian 5). I have read that there is a possibility of using a Java wrapper, but isn't there any other option which is easier to implement? Can't I just use a Unix command such as xxx java -jar program.jar?
Well, if you want to run your java program even when you exit out of your shell, the following is the most simple way:
$nohup java -jar program.jar &
You need to create an appropriate script in /etc/init.d and link it to /etc/rcX.d directories. The script should support at least start, stop, and status parameters. During start it should run java command with appropriate arguments, probably via nohup java <arguments> &. Then you should save PID of your newly-started process to file /var/run/yourservice.pid. stop command should read this PID file and kill this service.
The details vary from distribution to distribution, most distributions provide some macros to make whole job easier. It's best to look at examples of other services in /etc/init.d for your distribution.
Additionally:
If your service isn't accessed from other computers from the network, but it opens some port, make it unavailable with firewall.
If your service processes some 'delicate' data, it's good to add another user and invoke an appropriate sudo command in your /etc/init.d file.
You can start it as:
java -jar program.jar
Unix daemons are normally started by init or started by a script in /etc/init.d or /etc/rc.d, and started at specific runlevels - normally by soft links in /etc/rcX.d. (where X is the intended "runlevel" which is normally 3.
I think debian are moving to using "upstart", a init-replacement. It uses config files in /etc/init to define jobs, and they are quite easy to write. Check that out.
Daemons traditionally closes stdin, sdtout and stderr, and does a "double fork" when starting, in order to detach from the session and also to signal that they are ready to handle whatever they should handle. This is not really necessary, as long as the daemon is not started from the terminal.
If you want a simple shell wrapper to start you program; you just need to write a small shell script:
#!/bin/sh
/full/path/to/java -jar /full/path/to/program.jar
... and make it executable (chmod 755 )
This article contains a few useful tricks for running a Java application as a daemon:
http://barelyenough.org/blog/2005/03/java-daemon/
Alternatively, you can have a look at the Apache Commons Daemon project, although this requires native code (Unix and Win32 supported):
http://commons.apache.org/daemon/
You can use a cron job to schedule your program. You can also check out this article for details on how to run scripts on startup. You can write a script that runs your java program and run it on startup as mentioned in the article.

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