Threading nightmare


#1

The scenario (for test purposes) I’m trying to accomplish when running
rake on a new Rakefile is:

  1. start a java server (which doesn’t have an option to ‘daemonize’
    it) and get its pid
  2. interact with the server by sending things or accessing it
  3. stop the server

I’ve tried using IO’s popen, fork, thread, even sending the server to
/dev/null when starting it but none of them work as I expected. Once
the server (step 1) starts it just hangs in there, not letting the
following steps to run. But if I kill the server (control+c) the step
2 tries to run and fails because the server is no longer running.

Any ideas how it can be done?

Thanks a lot.

Thiago


#2

On 1/10/07, Thiago J. removed_email_address@domain.invalid wrote:

the server (step 1) starts it just hangs in there, not letting the
following steps to run. But if I kill the server (control+c) the step
2 tries to run and fails because the server is no longer running.

If you’re on a non-Windows system, then you can use Ara’s “slave” gem.

Check out Ara’s “systemu” gem as well – although I do not think it
allows you to send information to the forked process.

Blessings,
TwP


#3

Tim,

I’m on a unix box but I’m trying to accomplish this without having to
be system specific. If I have no choice than I’ll have to do it only
for *nix systems.

Thiago


#4

On 1/10/07, Thiago J. removed_email_address@domain.invalid wrote:

Tim,

I’m on a unix box but I’m trying to accomplish this without having to
be system specific. If I have no choice than I’ll have to do it only
for *nix systems.

Also, check out popen4. There is a Windows version and Unix version.
Both do what you need, but you’ll have platform specific code in your
script.

Blessings,
TwP


#5

Thanks for the help, but I was able to accomplish it using a
combination of fork, STDERR and exec and it seems to be working fine.

Thiago


#6

On Thu, 11 Jan 2007, Thiago J. wrote:

The scenario (for test purposes) I’m trying to accomplish when running
rake on a new Rakefile is:

  1. start a java server (which doesn’t have an option to ‘daemonize’
    it) and get its pid
  2. interact with the server by sending things or accessing it
  3. stop the server

you don’t have an easy choice. if you want to interact you’ll want to
be unix
specifc.

how do you want to interact? via stdin/stdout? does the process need
to be a
daemon or should it depend on the process controlling it also existing?
is
the controlling process transient or permanent?

I’ve tried using IO’s popen, fork, thread, even sending the server to
/dev/null when starting it but none of them work as I expected.

does the server allow itself to run without a tty? some programs don’t
and
then you’ll need to use the ruby pty lib. this would also limit you to
unix.

Once the

server (step 1) starts it just hangs in there, not letting the following
steps to run.

is it waiting for input?

But if I kill the server (control+c) the step 2 tries to

run and fails because the server is no longer running.

makes sense…

regards.

-a