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Bash: Regulating the number of processes a script can spawn

 
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Top Forums UNIX for Dummies Questions & Answers Bash: Regulating the number of processes a script can spawn
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Old 05-08-2010
achenle,
your approach looks very promising, but I have following questions:

1. What does "set -bm" stand for?
2. How does the flow look like? There are two variants I can think of:
Let's assume every job will run for 5 minutes and let's forget about that SIGCHLD thing.
2.a It starts with line 20, the function startjob is called, "started=$(($started+1))" does *NOT* take effect, 1st job gets started, $count=1, line 20 calls the startjob function again ................................. $count=100 !! All 100 jobs are running at the same time.
2.b It starts with line 20, the function startjob is called, $started=1, 1st job gets started, $count=1, .... Script ends after 10 jobs, because $started=10.
3. IMHO that "wait" line is pretty unnecessary (pls. correct me if I'm wrong)

Is there an error in the way I think how it will work Smilie
 
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LEARN ABOUT FREEBSD

posix_spawnattr_getschedpolicy

POSIX_SPAWNATTR_GETSCHEDPOLICY(3)			   BSD Library Functions Manual 			 POSIX_SPAWNATTR_GETSCHEDPOLICY(3)

NAME

     posix_spawnattr_getschedpolicy, posix_spawnattr_setschedpolicy -- get and set the spawn-schedpolicy attribute of a spawn attributes object

LIBRARY

     Standard C Library (libc, -lc)

SYNOPSIS

     #include <spawn.h>

     int
     posix_spawnattr_getschedpolicy(const posix_spawnattr_t *restrict attr, int *restrict schedpolicy);

     int
     posix_spawnattr_setschedpolicy(posix_spawnattr_t *attr, int schedpolicy);

DESCRIPTION

     The posix_spawnattr_getschedpolicy() function obtains the value of the spawn-schedpolicy attribute from the attributes object referenced by
     attr.

     The posix_spawnattr_setschedpolicy() function sets the spawn-schedpolicy attribute in an initialized attributes object referenced by attr.

     The spawn-schedpolicy attribute represents the scheduling policy to be assigned to the new process image in a spawn operation (if
     POSIX_SPAWN_SETSCHEDULER is set in the spawn-flags attribute).  The default value of this attribute is unspecified.

RETURN VALUES

     The posix_spawnattr_getschedpolicy() and posix_spawnattr_setschedpolicy() functions return zero.

SEE ALSO

     posix_spawn(3), posix_spawnattr_destroy(3), posix_spawnattr_getschedparam(3), posix_spawnattr_init(3), posix_spawnattr_setschedparam(3),
     posix_spawnp(3)

STANDARDS

     The posix_spawnattr_getschedpolicy() and posix_spawnattr_setschedpolicy() functions conform to IEEE Std 1003.1-2001 (``POSIX.1'').

HISTORY

     The posix_spawnattr_getschedpolicy() and posix_spawnattr_setschedpolicy() functions first appeared in FreeBSD 8.0.

AUTHORS

     Ed Schouten <ed@FreeBSD.org>

BSD
								  March 24, 2008							       BSD