Bash 并行进程模拟脚本

Question

我想编写模拟运行几个并发进程的 bash 脚本。
MAX_CONCURRENT_TASKS 表示一次可以运行多少个任务，而每个任务随机“工作”2-6 秒。

如果当前进程计数等于MAX_CONCURRENT_TASKS 和sleep 2~6 秒，是否有比简单的while..do 循环和使用wait 更“创造性”的方法来做到这一点？
任何人都知道如何为此使用信号？也许还有别的？

@EDIT：我想编写一个脚本来完成这项工作，我知道可以做到这一点的工具。

Answer 1

使用GNU Parallel。

for i in `seq 1 1000`; do
    echo "someFile$i"
done | parallel -j10 'md5sum {}'

一些简单的例子

Answer 2

是的，试试这个，我想你会喜欢的。尝试将 THREADLIMIT 和 MAXTHREADDUR 调整为您的参数。

这个程序确实应该被称为进程生成管理器，但这只是由于 BASH 在使用 & 符号进行分叉时的工作方式，它使用 fork() 或可能克隆到单独的 clone() 系统调用内存空间，而不是像 pthread_create() 这样共享内存的东西。如果 BASH 支持后者，则每个“执行序列”将运行相同，可以称为传统线程，同时获得更有效的内存占用。但是在功能上它的工作原理是一样的，尽管有点困难，因为每个工作克隆中都没有 GLOBAL 变量，因此使用进程间通信文件和基本的群信号量来管理关键部分。从 BASH 分叉当然是这里的基本答案，但我觉得好像人们知道这一点，但真的希望管理产生的内容，而不是仅仅分叉并忘记它。这演示了一种管理多达 200 个分叉进程实例的方法，这些进程都访问单个资源。我希望你喜欢它，我喜欢写它

#!/bin/bash

ME=$(basename $0)
IPC="/tmp/$ME.ipc"  #interprocess communication file (global thread accounting stats)
DBG=/tmp/$ME.log
echo 0 > $IPC           #initalize counter
F1=thread
SPAWNED=0       
COMPLETE=0
SPAWN=10000     #number of jobs to process
SPEEDFACTOR=1           #dynamically compensates for execution time
THREADLIMIT=200     #maximum concurrent threads
TPS=1                   #threads per second delay
THREADCOUNT=0           #number of running threads
SCALE="scale=5"         #controls bc's precision
START=$(date +%s)       #whence we began
MAXTHREADDUR=30         #maximum thread life span - demo mode

LOWER=$[$THREADLIMIT*100*90/10000]   #90% worker utilization threshold
UPPER=$[$THREADLIMIT*100*95/10000]   #95% worker utilization threshold
DELTA=10                             #initial percent speed change

threadspeed()        #dynamically adjust spawn rate based on worker utilization
{
   #vaguely assumes thread execution average will be consistent 
   THREADCOUNT=$(threadcount)
   if [ $THREADCOUNT -ge $LOWER ] && [ $THREADCOUNT -le $UPPER ] ;then 
      echo SPEED HOLD >> $DBG
      return
   elif [ $THREADCOUNT -lt $LOWER ] ;then 
      #if maxthread is free speed up
      SPEEDFACTOR=$(echo "$SCALE;$SPEEDFACTOR*(1-($DELTA/100))"|bc)
      echo SPEED UP $DELTA%>> $DBG
   elif [ $THREADCOUNT -gt $UPPER ];then
      #if maxthread is active then slow down
      SPEEDFACTOR=$(echo "$SCALE;$SPEEDFACTOR*(1+($DELTA/100))"|bc)
      DELTA=1                            #begin fine grain control
      echo SLOW DOWN $DELTA%>> $DBG
   fi

   echo SPEEDFACTOR $SPEEDFACTOR >> $DBG

   #average thread duration   (total elapsed time / number of threads completed)
   #if threads completed is zero (less than 100), default to maxdelay/2  maxthreads

   COMPLETE=$(cat $IPC)

   if [ -z $COMPLETE ];then
      echo BAD IPC READ ============================================== >> $DBG
      return  
   fi

   #echo Threads COMPLETE $COMPLETE >> $DBG
   if [ $COMPLETE -lt 100 ];then
      AVGTHREAD=$(echo "$SCALE;$MAXTHREADDUR/2"|bc)
   else
      ELAPSED=$[$(date +%s)-$START]
      #echo Elapsed Time $ELAPSED >> $DBG
      AVGTHREAD=$(echo "$SCALE;$ELAPSED/$COMPLETE*$THREADLIMIT"|bc)
   fi
   echo AVGTHREAD Duration is $AVGTHREAD >> $DBG

   #calculate timing to achieve spawning each workers fast enough
   # to utilize threadlimit - average time it takes to complete one thread / max number of threads
   TPS=$(echo "$SCALE;($AVGTHREAD/$THREADLIMIT)*$SPEEDFACTOR"|bc)
   #TPS=$(echo "$SCALE;$AVGTHREAD/$THREADLIMIT"|bc)  # maintains pretty good 
   #echo TPS $TPS >> $DBG

}
function plot()
{
   echo -en \\033[${2}\;${1}H

   if [ -n "$3" ];then
         if [[ $4 = "good" ]];then
            echo -en "\\033[1;32m"
         elif [[ $4 = "warn" ]];then
            echo -en "\\033[1;33m"
         elif [[ $4 = "fail" ]];then
            echo -en "\\033[1;31m"
         elif [[ $4 = "crit" ]];then
            echo -en "\\033[1;31;4m"
         fi
   fi
      echo -n "$3"
      echo -en "\\033[0;39m"
}

trackthread()   #displays thread status
{
   WORKERID=$1
   THREADID=$2
   ACTION=$3    #setactive | setfree | update
   AGE=$4

   TS=$(date +%s)

   COL=$[(($WORKERID-1)/50)*40]
   ROW=$[(($WORKERID-1)%50)+1]

   case $ACTION in
      "setactive" )
         touch /tmp/$ME.$F1$WORKERID  #redundant - see main loop 
         #echo created file $ME.$F1$WORKERID >> $DBG
         plot $COL $ROW "Worker$WORKERID: ACTIVE-TID:$THREADID INIT    " good
         ;;
      "update" )
         plot $COL $ROW "Worker$WORKERID: ACTIVE-TID:$THREADID AGE:$AGE" warn
         ;;
      "setfree" )
         plot $COL $ROW "Worker$WORKERID: FREE                         " fail
         rm /tmp/$ME.$F1$WORKERID 
         ;;
      * )

      ;;
   esac
}

getfreeworkerid()
{
   for i in $(seq 1 $[$THREADLIMIT+1])
   do 
      if [ ! -e /tmp/$ME.$F1$i ];then
         #echo "getfreeworkerid returned $i" >> $DBG
         break
      fi
   done
   if [ $i -eq $[$THREADLIMIT+1] ];then
      #echo "no free threads" >> $DBG
      echo 0
      #exit
   else
      echo $i
   fi
}

updateIPC()
{
   COMPLETE=$(cat $IPC)        #read IPC
   COMPLETE=$[$COMPLETE+1]     #increment IPC
   echo $COMPLETE > $IPC       #write back to IPC
}


worker() 
{
   WORKERID=$1
   THREADID=$2
   #echo "new worker WORKERID:$WORKERID THREADID:$THREADID" >> $DBG 

   #accessing common terminal requires critical blocking section
   (flock -x -w 10 201
      trackthread $WORKERID $THREADID setactive
   )201>/tmp/$ME.lock

   let "RND = $RANDOM % $MAXTHREADDUR +1"

   for s in $(seq 1 $RND)       #simulate random lifespan
   do
      sleep 1;
      (flock -x -w 10 201
         trackthread $WORKERID $THREADID update $s
      )201>/tmp/$ME.lock
   done

   (flock -x -w 10 201
      trackthread $WORKERID $THREADID setfree
   )201>/tmp/$ME.lock

   (flock -x -w 10 201
      updateIPC
   )201>/tmp/$ME.lock
}

threadcount()
{
   TC=$(ls /tmp/$ME.$F1* 2> /dev/null | wc -l)
   #echo threadcount is $TC >> $DBG
   THREADCOUNT=$TC
   echo $TC
}

status()
{
   #summary status line
   COMPLETE=$(cat $IPC)
   plot 1 $[$THREADLIMIT+2] "WORKERS $(threadcount)/$THREADLIMIT  SPAWNED $SPAWNED/$SPAWN  COMPLETE $COMPLETE/$SPAWN SF=$SPEEDFACTOR TIMING=$TPS"
   echo -en '\033[K'                   #clear to end of line
}

function main()
{
   while [ $SPAWNED -lt $SPAWN ]
   do 
      while [ $(threadcount) -lt $THREADLIMIT ] && [ $SPAWNED -lt $SPAWN ]
      do
         WID=$(getfreeworkerid)
         worker $WID $SPAWNED &
         touch /tmp/$ME.$F1$WID    #if this loops faster than file creation in the worker thread it steps on itself, thread tracking is best in main loop 
         SPAWNED=$[$SPAWNED+1]
         (flock -x -w 10 201
            status
         )201>/tmp/$ME.lock
         sleep $TPS
        if ((! $[$SPAWNED%100]));then
           #rethink thread timing every 100 threads
           threadspeed
        fi
      done
      sleep $TPS
   done

   while [ "$(threadcount)" -gt 0 ]
   do
      (flock -x -w 10 201
         status
      )201>/tmp/$ME.lock
      sleep 1;
   done

   status
}

clear
threadspeed
main
wait
status
echo