Develop Reference

Install4j: Is is possible to configure an install4j launcher to respond to kill -3 and generate a thread dump?

I would like to automatically create a thread dump as part of a log collection script I have written.
I know that it is possible to generate a thread dump using jstack or kill -3 . The customer running the log collection script will only have a JRE installed so jstack is not an option.
If I use jstack and the pid of the JVM that the install4j launcher creates I get the thread dump...however invoking kill -3 with the same pid generates no output. I am currently directing both stderror and stdout to files using the install4j launcher configuration.
This is a linux launcher that is configured with the service option.
FWIW...I have tried not directing the output and also running my application as a console program instead of a service and none of these allow 'kill -3' to work.
I'm using install4j 6.0
Lastly, I do not want to use -XX:+UnlockDiagnosticVMOptions -XX:+LogVMOutput -XX:LogFile=dump.log because of the unknown overhead it might create.
Any help would be appreciated!

I would suggest to use the ThreadMXBean to get this information programmatically in the same process rather than use signal handlers from another process. The API documentation is at
http://docs.oracle.com/javase/8/docs/api/java/lang/management/ThreadMXBean.html
Here's a full example of how to use this MBean.
In that way you can write the information explicitly to wherever you want it to go.

Running Java application from C# properly

I am trying to execute Java application from my c# code. I use Process class from System.Diagnostics.
I am able to run it and kill, but it seems that java starts subprocess when I am executing application. And when I am trying to kill the Process, I kill the parent java process, the second one, which was started behind the scenes, is still running.
Multiple executions of this logic cause dozens of java.exe processes and memory overflow.
Is there a way to do such thing as proper running Java application from c# code and be able to kill started processes?
I wonder if it is possible at all to resolve this issue if I don't have administrative rights

I would be tempted to use taskkill. It runs from this cmd command:
string.Format("cmd /c \"taskkill /f /pid {0}\" /t", this.processId);
the /t does a tree kill, that ends the child processes.

Find and kill a specific Java process from another Java App

I have several java processes running on a windows machine. I have a Java process which is supposed to monitor the other processes and periodically kill or restart new ones.
If I have a java process running com.foo.Main1 and one running com.foo.Main2 - how can my monitoring process find and kill just the Main2 process?
Update: I have some code that can execute a command line tasklist.exe and parse it, but no matter what I do, I only see the java.exe process, not which class is executing
Update 2: I do not have the ability to install non-java programs.

It's probably going to be a lot simpler using OS-specific tools and using Runtime.exec() to run them, but I'll try and give a platform independent answer:
It might be possible to do this platform independently using the Attach API. This comes with the JDK, so to use it just include tools.jar from your JDK on your program's classpath.
To get a list of virtual machines on the system, use VirtualMachine.list(). You can get/parse arguments from the virtual machine descriptor objects that are returned from this.
The attach API also allows you to load agents into already-running Java processes. Since you want to kill a Java process, you can write a Java agent that simply runs System.exit() (or if you really want it dead use Runtime.halt() instead) when the agent loads.
Once you identify the one you want to kill, attach to it and load the killer agent (the agent has to be built as a JAR file, accessible to the Java process it needs to be loaded into). Shortly after the agent is attached that process should die.
These links might help also:
An Oracle blog on the attach API
Package documentation for java.lang.instrument (has detailed instructions on how to build an agent JAR)

This is specific to Windows.
I was facing the same issue where I have to kill the specific java program using taskkill. When I run the java program, tasklist was showing the same program with Image name set as java.exe. But killing it using taskkill /F java.exe will stop all other java applications other than intended one which is not required.
So I run the same java program using:
start "MyProgramName" java java-program..
Here start command will open a new window and run the java program with window's title set to MyProgramName.
Now to kil this java-program use the following taskkill command:
taskkill /fi "MyProgramName"
Your Java program will be killed only. Rest will be unaffected.

killing a bash process does not kill the process the bash is currently running

The scenario is as follows: I have a java daemon, which is supposed to not terminate. However, in case of an unexpected error, the crashed JVM should be restarted by a script. So I wrote a command which starts a background bash which has a loop starting the JVM (so when the JVM terminates, it will be restarted again).
/bin/bash -c "while true; do java ...; done" &
In order to be able to stop the daemon, I thought of killing this bash background process (by saving it's process id in a file). This works insofar as the background bash doesn't restart the JVM, but still doesn't kill the currently running process - so the bash seems to end it's current command before it checks for a kill command. I would like to have the currently running JVM to be killed, too.
Since I don't want to manage 2 PIDs (one for the background bash and one for the currently running JVM), is there a way of "force kill" which by design stops the current command? (I couldn't find such thing in man kill)?

There are a number of process-management tools built for exactly this purpose: runit, daemontools, upstart... even an entry in the SysV inittab table.
All of these will automate restarting immediately on shutdown, track desired status as opposed to current status (and attempt to signal startup or shutdown as-desired), manage signal delivery, etc.
You can trap signals in bash and trigger events on them, but that only handles the subset which can be trapped (you can't trap a KILL, for instance). The better thing is to use a tool built-to-purpose.
The ProcessManagement page of the wooledge.org wiki (used by irc.freenode.org's #bash channel) has some other concrete suggestions on doing this yourself in bash... though it too suggests runit, daemontools, and their kin as the best-practices approach.

Why not use cron to start your app, and manage only 1 pid, the one belonging to your app? That way you'll always be killing the correct process.
Emphasising a bit, you could create a bash script to manage your app: start|stop|status. On start it will save the java pid to a file. Then you can schedule a cron job to verify the status of the app, and if the pid does not exist, relaunch it.

Isn't this the default behaviour of bash? I thought for example zsh does the opposite and doesn't send a SIGHUP to all child process? Maybe you can try this answer and write a little script and start it with disown?
see this question: Tie the life of a process to the shell that started it
I didn't test it but I need zsh in my webserver because I start it manually and exit my shell with double CTRL-D.

Is there a way to pause execution of a running Java program in Eclipse on Macbook Pro?

I use a MacBook Pro. Sometimes I want to pause the execution of a long heavy-duty experiment running on my system because I am on battery or for any other reason. Is there a way to do it in Eclipse ? Or even in Mac OS X itself ?

You can suspend any process in Mac OS X (or any Unix) using the kill command to send the SIGSTOP signal to the process.
Find the process ID (pid) for example we'll say it's 9281.
kill -SIGSTOP 9281
and to resume...
kill -SIGCONT 9281
To find the pid, use the ps command, ps -a will list all running processes, your process will be a java instance running your app.

You could start the application in debug mode and later pause it before setting the mac osx to sleep.

If you have already started the application, the best you can do is to use kill -STOP from the command line. You may need to do this to the eclipse process itself if the application is running in the eclipse jvm.

If the process is contained (no internet connection, no external dependency) just go to sleep or close the computer. It will be resumed after you turned it on.