在Java中将Shell脚本作为线程执行

Question

I need to execute a shell script in a java program. I figured out that i can use processbuilder and runtime.exec.. but my webserver times out every 180 sec but my script execution takes more than that..i do not want to use process for this approach.. is there any other way where i can use thread for this execution.

thanks.

Answer 1

I'm assuming that the response from the script is intended for humans to read.

Good interface design, and human nature, suggests that if your script is taking over 180 seconds to run, then it should be run separately from the web server. On linux, I would suggest putting it into 'cron', and letting it run on a regular basis. You would only serve the results of the script via the web server, with a response time in seconds instead of minutes.

If your script depends on parameters from the http request, or other information that is only available from within the web server's environment, you have the following choices.

1. If you can figure out the likely combinations of parameters, run the script automatically for each combination of parameters, again only serving the results through the web.
2. If the majority of the time is spent in a single command, and the results of that command don't change much between runs, move that command into a separate script that runs automatically, and use the results of that separate script to build the web response.
3. Break the response up into segments, only showing a portion of the data for each request, allowing the user to page through the response. The script would be rewritten to only request the necessary data for the current page, reducing the amount of time needed to obtain that data.
4. Rewrite the script in a compilable language, which might gain you enough time to make running it for every request reasonable. However, if the problem is a database query, this won't do you any good. You'd have to go with option (3), whether you rewrote it in a compilable language or not.

Without additional information, like an example of the script, or a description of where you're getting the results from, that's the best I can do.

Answer 2

A process can run several threads, but they still are parts of the process.

So, all threads inside a java program are the threads of the java process, and a thread cannot run another program's threads.

A shell script is ran by a program : the shell program ! (/bin/bash or /bin/sh)

Anyway a shell script will mostly ran other programs inside several other processes.

No, you cannot run a shell inside a thread of java.

Answer 3

In general, if you have code that is separate from your Java program, such as code that is in a separate script, then there is no justification for why your code would execute an outside script when that code could be instead integrated into the program. It is insecure at best. Your basically allowing arbitrary code to be executed by your program since the outside script is editable. What you are doing sounds to me almost like it should be confined either a unit test or a build task.

As a unit test task and you could use a threaded JUnit runner to run your outside script during the test phase of your project.

Also, separately from your program, you could also execute it using a Gradle task and by using the parallellforks option that Gradle has.