• Post Reply Bookmark Topic Watch Topic
  • New Topic
programming forums Java Mobile Certification Databases Caching Books Engineering Micro Controllers OS Languages Paradigms IDEs Build Tools Frameworks Application Servers Open Source This Site Careers Other Pie Elite all forums
this forum made possible by our volunteer staff, including ...
Marshals:
  • Tim Cooke
  • Campbell Ritchie
  • Ron McLeod
  • Junilu Lacar
  • Liutauras Vilda
Sheriffs:
  • Paul Clapham
  • Jeanne Boyarsky
  • Henry Wong
Saloon Keepers:
  • Tim Moores
  • Tim Holloway
  • Stephan van Hulst
  • Piet Souris
  • Carey Brown
Bartenders:
  • Jesse Duncan
  • Frits Walraven
  • Mikalai Zaikin

Issues with Runtime.exec Process.getInputStream and Process.waitFor().

 
Ranch Hand
Posts: 103
  • Mark post as helpful
  • send pies
    Number of slices to send:
    Optional 'thank-you' note:
  • Quote
  • Report post to moderator
Hi,
I have written a code to check whether HSQl, JBoss, Radius (AAA sever) and MySQL is running or not.The code is written in an inifinte while loop to continuously monitor.Now I tested that if this service(let's say hsql) is running then "/bin/bash -c ps -ef | grep 'hsql' | wc -l" will return 3 when this is passed as an argument in Runtime.exec() method.Now I have come to know following facts

1.The inputstream or errstream of the forked process must not be overflowed.Otherwise it 'll cause deadlock.

Keeping that in mind I have written this code



Output I'm expecting as follows

HSQL is running/not running 1
JBoss is running/not running 1
MySQL is running/not running 1
-------------------1----------------

HSQL is running/not running 2
JBoss is running/not running 2
MySQL is running/not running 2
-------------------2----------------

and so on...

Howevere I'm not getting like that.Some times HSQL's status message is not printed or sometimes JBoss status message is not printed.Even sometimes I got the output like
------------------1----------------------

after this status messages are printed.All I'm trying to say is that seems to be some race condition or some synchronization problem.

Thanks & Regards,
Arka




 
Greenhorn
Posts: 11
  • Mark post as helpful
  • send pies
    Number of slices to send:
    Optional 'thank-you' note:
  • Quote
  • Report post to moderator

Arka Sharma wrote:All I'm trying to say is that seems to be some race condition or some synchronization problem.



I wouldn't call it a problem exactly. Sometimes you want to execute a program and let it run independently while your Java program continues to run; it depends on what that program does.

About synchronous / asynchronous operation, yes, you are right. Quoting from the the JDK API's ProcessBuilder page:

There is no requirement that a process represented by a Process object execute asynchronously or concurrently with respect to the Java process that owns the Process object.



If you need the program to run synchronously, it is possible. I've done this in the past but can't remember exactly how I did it; I'll have to get back to you on this. If you're not opposed to using API's for this, the Apache Commons Exec project might be useful to you, but its documentation assumes you know how Java executes other programs in detail. Executing other programs with Java can be tricky.

CNH
 
pie. tiny ad:
Building a Better World in your Backyard by Paul Wheaton and Shawn Klassen-Koop
https://coderanch.com/wiki/718759/books/Building-World-Backyard-Paul-Wheaton
reply
    Bookmark Topic Watch Topic
  • New Topic