UNIX for Dummies Questions & Answers

Hi. Before throwing my question, thanks to everybody for paying attention. Sorry if my english isn't good enough, but it's not my mother tongue.

That's my question:

I have a java program that throws an external program with "Process p = Runtime.getRuntime.exec(***)". The communication between them is by xml files. Mi program writes a file that will be the input of the other, and the other one writes an output file wich my program reads after wait with "p.waitFor()". Both programs are executed in a remote server through an ssh connection.

My problem is, sometimes, my java program freezes. If I take a look to the running process with "ps -l" the result is similar to this:

Code:

F S   UID   PID  PPID  C PRI  NI ADDR SZ   WCHAN  TTY          TIME    CMD
0 S  712     ****  *******1  2  97  19     -     *****  184466      ?          **********    java
0 S  712     ****  ******  99  99   19       -   *****  pipe_w     ?          **********    ext.prog.

I'm not looking for someone to solve my whole problem, but if you could give me at least some clues about what does pipe_w means and what could cause it I'd be very grateful.

Thanks a lot.

Edit: I forgot to say that it doesn't happen always. For example, sometimes it fail all the executions over an hour, and sometimes it works fine all day. I don't know if it's about my program, something that it's happening in the server...

Edit again: This is the actual situation. The other one was a "reconstruction" xD

Code:

0 S   712 26295     1  0  97  19 - 365416 184466 ?       00:02:47   java
0 S   712 29201 26295  0  99  19 - 60796 pipe_w ?        00:00:00 **********

---------- Post updated 20-11-09 at 02:22 AM ---------- Previous update was 19-11-09 at 11:27 AM ----------

I found the problem, thank you. It was a bug in the external program that produced an unfinished loop. I think you can close this thread.

Sorry for the quotes.

It's a wait state on read/write against a pipe.

If you own the processes, run strace. I am guessing you'll see your process waiting on a read from some other process. It is called a deadlock condition.

I've only seen pipe_w in Linux so I'm assuming you are on Linux. Your OS information might help.

Yes, I'm on Linux. Sorry.

Thanks for the info. Like I said, I found the actual problem, but it's good to know.