Shell Programming and Scripting

  1 #!/bin/bash
  2 
  3 ##
  4 ## process_runner.sh <concurrent> <total procs>
  5 ##
  6 ## Example script given the maximum number of processes to
  7 ## run concurrently, c, and the total number of processes, n
  8 ## runs at most c, processes in the background until all n
  9 ## Have been run.
 10 ##
 11 ## Author Donald 'Paddy' McCarthy Dec. 17 2007
 12 ##
 13 
 14 # how many processes to run in parallel
 15 concurrent=$1
 16 # total processes to run
 17 maxprocs=$2
 18 
 19 printf "\n## STARTING %i Processes, %i at a time\n\n" \
 20   $maxprocs $concurrent
 21 
 22 
 23 # main loop wait time between checking background procs.
 24 tick=1
 25 
 26 
 27 # dummy processes sleep for a random time
 28 function runproc {
 29   local -i n=$1
 30   local -i j
 31   (( j = 5+$RANDOM*10/32767 ))
 32   #(date; printf "#>>>JOB %i : Sleeping for %i\n" $n $j)
 33   printf "OUT JOB ,%03i, Sleep for ,%2i,  , @,%s\n" $n $j "`date`"
 34   sleep $j
 35   returned=$?
 36   printf "IN  JOB ,%03i, Slept for ,%2i, returned ,%i, @,%s\n" \
 37     $n $j $returned "`date`"
 38   #(date; printf "#<<<JOB %i : Slept for %i\n" $n $j)
 39 }
 40 
 41 function print_runstats {
 42   printf '# %i Jobs in background. %i/%i started\n\n'  \
 43     `jobs -r|wc -l` $ran $maxprocs
 44 }
 45 
 46 # Bash array running keeps track of the background process numbers
 47 # Start with nothing running (sentinel value will not be a process number
 48 for ((i=0; i<$concurrent; i+=1 )); do running[$i]=123456789; done
 49 
 50 ran=0
 51 until
 52   while [ $ran -lt $maxprocs ]; do
 53     for ((p=0; p<$concurrent; p+=1 )); do
 54       proc=${running[$p]}
 55       # Over all running processes...
 56       # $proc still running?
 57       ps -p $proc | fgrep $proc >/dev/null
 58       if [ $? -ne '0' ] ; then
 59         # Not found  i.e. finished
 60         # Run another in background and store the proc number
 61         runproc $ran &
 62         running[$p]=$!
 63         ((ran+=1))
 64         if [ $ran -ge $maxprocs ]; then break 1; fi
 65       fi
 66     done
 67     sleep $tick
 68     # Status
 69     print_runstats
 70   done
 71 
 72   sleep $tick
 73   # Status
 74   print_runstats
 75 do [  `jobs -r|wc -l` -eq 0 ]
 76 done
 77 wait
 78 printf "\n## FINISHED\n"
 79 
 80 exit 0
 81 
 82 sample_output=<<!
 83 bash$ ./process_runner.sh 2 5
 84 
 85 ## STARTING 5 Processes, 2 at a time
 86 
 87 OUT JOB ,000, Sleep for ,10,  , @,Tue Dec 18 09:26:00 GMTST 2007
 88 OUT JOB ,001, Sleep for , 8,  , @,Tue Dec 18 09:26:00 GMTST 2007
 89 # 2 Jobs in background. 2/5 started
 90 
 91 # 2 Jobs in background. 2/5 started
 92 
 93 # 2 Jobs in background. 2/5 started
 94 
 95 # 2 Jobs in background. 2/5 started
 96 
 97 # 2 Jobs in background. 2/5 started
 98 
 99 # 2 Jobs in background. 2/5 started
100 
101 IN  JOB ,001, Slept for , 8, returned ,0, @,Tue Dec 18 09:26:09 GMTST 2007
102 # 1 Jobs in background. 2/5 started
103 
104 OUT JOB ,002, Sleep for ,11,  , @,Tue Dec 18 09:26:09 GMTST 2007
105 IN  JOB ,000, Slept for ,10, returned ,0, @,Tue Dec 18 09:26:10 GMTST 2007
106 # 2 Jobs in background. 3/5 started
107 
108 OUT JOB ,003, Sleep for , 7,  , @,Tue Dec 18 09:26:11 GMTST 2007
109 # 2 Jobs in background. 4/5 started
110 
111 # 2 Jobs in background. 4/5 started
112 
113 # 2 Jobs in background. 4/5 started
114 
115 # 2 Jobs in background. 4/5 started
116 
117 # 2 Jobs in background. 4/5 started
118 
119 IN  JOB ,003, Slept for , 7, returned ,0, @,Tue Dec 18 09:26:18 GMTST 2007
120 # 1 Jobs in background. 4/5 started
121 
122 OUT JOB ,004, Sleep for , 6,  , @,Tue Dec 18 09:26:19 GMTST 2007
123 # 2 Jobs in background. 5/5 started
124 
125 IN  JOB ,002, Slept for ,11, returned ,0, @,Tue Dec 18 09:26:20 GMTST 2007
126 # 1 Jobs in background. 5/5 started
127 
128 IN  JOB ,004, Slept for , 6, returned ,0, @,Tue Dec 18 09:26:25 GMTST 2007
129 
130 ## FINISHED
131 !
132 
133 
134