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Top Forums Shell Programming and Scripting BASH Execution Delay / Speedup Post 302933014 by Don Cragun on Tuesday 27th of January 2015 03:07:37 AM
Old 01-27-2015
So, from this code it seems that your intention is to simultaneously run an infinite number of jobs for every line in some file on your system. You do not care if any of these jobs start successfully. You do not care if any of these jobs complete successfully (or at all). You believe that you should be able to start an infinite number of jobs and all of those jobs should run as though they are the only job running on your system.

Unfortunately, I do not know of any system that will act anything at all like that. Nor, do I understand why you need an infinite loop to read lines in a file forever. Presumably your script terminates when the system kills it because it realizes you have exhausted system resources.

You say that a while read loop performs about the same way. You are correct in noting that an infinite loop is an infinite loop, but a while read loop would only have needed one process per line processed while your current nested loops use four processes per line processed plus 3 processes each time the file is processed. And, and a while read loop would read your file once each time you process the file while your current code reads the entire file n+1 times if your file contains n lines.

If, instead of processing a single file an infinite number of times, you want to process each line in a file once; and if instead of ignoring the success or failure of all of the jobs you start, you'd like to actually log any failures that might occur during processing and not terminate your script until all lines have been processed, tell us more about your system:
  1. Given the expected load on your system and the number of processors available to run your script, how many simultaneous processes should your script expect to be able to run?
  2. What does my_job do? (If it doesn't exit with a zero exit status if it completes successfully and exit with a non-zero exit status if it does not complete successfully, rewrite it so it does! If it exits before all children it has started have completed, rewrite it so it doesn't return until all of its children have finished!)
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mailq(1)						      General Commands Manual							  mailq(1)

NAME
mailq - prints the mail queue SYNOPSIS
DESCRIPTION
prints a summary of the mail messages queued for future delivery. The first line printed for each message shows the internal identifier used on this host for the message, the size of the message in bytes, the date and time the message was accepted into the queue, and the envelope sender of the message. The second line shows the error message that caused this message to be retained in the queue; it will not be present if the message is being processed for the first time. The status characters are: to indicate that the job is being processed to indicate that the load is too high to process the job to indicate that the job is too new in the queue to process. The output lines that follow the second line show the message recipients, one per line. is identical to Options The supported options are: Show the mail submission queue specified in the file instead of the MTA queue specified in the file. Show the lost items in the mail queue instead of normal queue items. Show the quarantined items in the mail queue instead of the normal queue items. Limit processed jobs to those containing substr as a substring of the queue ID or not when is specified. Limit processed jobs to quarantined jobs containing substr as a substring of the quarantine reason or not when is specified. Limit processed jobs to those containing substr as a substring of one of the recipients or not when is specified. Limit processed jobs to those containing substr as a substring of the sender or not when is specified. Print verbose information. This adds the priority of the message and a single character indicator or blank) indicating whether a warning message has been sent on the first line of the message. In addition, extra lines may be intermixed with the recipients indicating the `controlling user' information. This shows who owns the programs that are executed on behalf of this message and the name of the alias this command expanded from, if any. RETURN VALUE
The utility exits with 0 on success, and >0 if an error occurs. AUTHOR
was developed by the University of California, Berkeley, and originally appeared in 4.0BSD. FILES
mail queue files for SEE ALSO
sendmail(1M). mailq(1)
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