Shell Programming and Scripting

I have a BASH script that runs a continuous loop, reading a line from a file, and then spawning a background process to use it. I've placed "date" commands inside it to see where it's slowing down, and everything inside -- including reading the line from the file -- is fast, but the loop bogs down AROUND THE "DONE" STATEMENT. Before the end of the loop and getting back to the top often takes 30 to 200 seconds!!

I've tried many things to no avail. I've also limited the number of background processes from 400 all the way down to ZERO (runs the single command in foreground), but the end of the loop is a KILLER.

HELP ME UNDERSTAND THIS (and fix it!!)

As we have nothing or no code to view and test then we cannot possibly hazard a guess.

Please give us the script or something similar so that we can emulate your problem.

OS, machine, bash version and any other details would be of help to us too...

TIA...

Code:

while [ true ] do

(copy a text file over if out of lines)

while [ pointer is less than end of file ] do

  (spawn a job) < ------ background (&) or foreground both take over 30-100 seconds to get past this

done
done

---------- Post updated at 05:13 PM ---------- Previous update was at 05:08 PM ----------

Okay -- I posted the code, and here are some details. I'm running BASH on Redhat Linux 4.6 on an HP server, and I'm usually the only person running on the machine.

Thanks for the quick reply, BTW!! MUCH appreciated!

We are going to need to know what (spawn a job) actually is before we can tell you why it's taking 300 seconds to complete.

What the job does is take that line of the file that it's given as an argument and uses that to make seven or eight data accesses. Right now they're stubs, but in the future, they'll be accessing some hardware that may take awhile. Hence, spawning the job to run in background.

At first, I thought that running over 200 of these jobs as bogging down the machine. So I reduced the number, and reduced and reduced until I had a single job that made some accesses and exited. Still a huge delay at the end of the loop. But there's no testing there -- it's just supposed to return and run the loop again. The test for the line number in the file is in the inner loop. The outer loop continues reading a new copy of the external file *inside* the loop, not where the slowdown is occurring. Not knowing exactly what BASH is doing internally, I don't know what's going on at the head and footer of the loop. But it occasionally slows down a LOT.

And without seeing your actual bash script, we don't know what's going on at the head and footer of your loop.

I can imagine lots of things you could be doing that would cause the symptoms you're seeing. But instead of us guessing at what you're doing, why don't you actually show us your code so we can give you some input that might actually make a difference in the way your code runs???

I am using BASH 4.1.2 on the Linux machine.

Since I've said I've "spawned" the job at that point in background, but folks are saying that it may still be responsible for the slowdown, is there some sort of delay in starting a job like that that may slow down the main loop regardless of it taking awhile to start running independently?