The popen method found in jruby/core/src/main/java/org/jruby/RubyIO.java. It calls into the Ruby19POpen class.

There's a block of code in the Ruby19POpen class that is changing forward slashes to back slashes. It may be doing it where it should not:

 if (Platform.IS_WINDOWS) {
  String commandString = _cmd.convertToString().toString().replace('/', '\\');
   _cmd = runtime.newString(commandString);
   if (_cmdPlusArgs != null) _cmdPlusArgs[0] = _cmd;
   } else {
      _cmd = _cmd.convertToString();
      if (_cmdPlusArgs != null) _cmdPlusArgs[0] = _cmd;
 }

For example, the forward slash in the following command should not be converted to a backslash:

typeperf "\Processor Information(*)\Interrupts/sec"

@NickMRamirez Can you try again with a newer version of JRuby 9.0.0.0 please? There were a lot of changes made since 9.0.0.0.pre2. The current release is 9.0.1.0.

@nirvdrum I updated to jruby 9.0.1.0 (2.2.2) 2015-09-02 58f336. The problem still exists.

Running: jruby -S irb

And then:

IO.popen('typeperf "\Processor Information(*)\Interrupts/sec"') { |o| o.each { |line| puts line }}

Displays:
Exiting, please wait...
Error: No valid counters.

Can i do any workaround for this problem?

@erikpar Using Open3.popen3 seemed to work, but I couldn't get my unit tests to pass when I switched to using it. But in a pinch, you might try downloading and building the logstash-input-perfmon plugin and changing the call to IO.popen to use Open3.popen3 instead. Its usage isn't exactly the same, so you'd have to change things up a little, but only a little in the code around that call to IO.popen. Until jruby is fixed.

Didn't managed to make it work

@erikpar Since JRuby's IO.popen is buggy for Windows, I have changed the logstash-input-perfmon plugin to use Open3.popen3 instead. I will push to rubygems sometime soon, but you can get the source now.

Thanks its working :-)

This is still a problem in JRuby 9.0.5.0

I believe this is still an issue at least in 9.1.13.0:

irb(main):001:0> IO.popen("curl -v http://www.google.com")
=> #<IO:fd 100675>
* Rebuilt URL to: http:\\www.google.com/
* Port number ended with '\'
* Closing connection -1
curl: (3) Port number ended with '\'

Also the code mentioned above by @NickMRamirez is still there: https://github.com/jruby/jruby/blob/master/core/src/main/java/org/jruby/RubyIO.java#L3972-L3975