如何解决Python脚本创建重复的进程
我的python3脚本创建了自己的副本。它不应该这样做，我也不知道它是如何（或为什么）这样做的。为什么要创建重复项，以及如何阻止这样做？
两个进程同时运行，并且彼此不干扰。但是，脚本会监视目录并根据添加到该目录的文件发布MQTT消息。最终结果是，MQTT代理收到两条相同的消息，彼此间隔几秒钟，每个进程一条。
该脚本是从命令行调用的。
$ python3 fwedge_camera.py -i local_camera.json -b ignition_broker.json
在ps -ef中，看起来只有一个过程：
$ ps -ef
UID PID PPID C STIME TTY TIME CMD
...
devuser 11971 11958 0 14:13 pts/1 00:00:00 /bin/bash
devuser 12046 11971 39 15:17 pts/1 00:01:48 python3 fwedge_camera.py -i local_camera.json -b ignition_broker.json
在htop中可见重复的过程：
__PID USER PRI NI VIRT RES SHR S cpu% MEM% TIME+ Command
11971 devuser 20 0 2960 1640 1172 S 0.0 0.2 0:00.12 /bin/bash
12046 devuser 20 0 47564 25636 3500 R 47.7 2.5 2:41.12 `- python3 fwedge_camera.py -i local_camera.json -b ig
12054 devuser 20 0 47564 25636 3500 S 0.0 2.5 0:00.52 `- python3 fwedge_camera.py -i local_camera.json -b
12053 devuser 20 0 47564 25636 3500 R 48.4 2.5 2:32.86 `- python3 fwedge_camera.py -i local_camera.json -b
两个进程之间的资源分配总是这样的；第一个过程消耗了大部分资源。
这是源代码。我省略了250行数据处理和MQTT发布。我将根据要求发布未删节的消息源。
# File fwedge_camera.py
#
# This version of `fwedge_camera.py` performs the following tasks:
# - Watch the directories at:
# /home/devuser/xxxxx/<date>/<time>/
# for added files.
# - Extract data from the `prediction.txt` file.
# - Publish the data using MQTT Sparkplug B.
# - Publish the `image.txt` file using MQTT Sparkplug B.
from binascii import b2a_base64
from datetime import datetime
import getopt
import json
import os # for remove,listdir,environ,path.getsize
from re import split
import string
import sys
from time import sleep
import paho.mqtt.client as mqtt
from watchdog.observers.polling import PollingObserver
from watchdog.events import PatternMatchingEventHandler
sys.path.insert(0,"./tahu/client_libraries/python/")
import sparkplug_b as sparkplug
from sparkplug_b import *
from date_to_epoch import date_to_epoch
from mulato import Mulato
from clibridge import read_setting_value
# [ ... 250 lines deleted ... ]
##### Main part of program #####
def usage():
print('python parse_chooch.py <options>')
print('Options:')
print('-h or --help : print this message')
print('-i <file.json> or --input=<file.json> : specify input device')
print('-b <file.json> or --broker=<file.json> : specify MQTT broker')
print('--debug : debug (verbose) output')
def parse_cmdline(argv):
debug_flag = False
local_file = ""
mqtt_file = ""
# logprint("Args are:",argv)
try:
opts,args = getopt.getopt(argv,"hi:b:",["help","input-device=","broker=","debug"])
except getopt.GetoptError:
logprint("Error: Command line Syntax error")
print("Error: Command line Syntax error")
usage()
sys.exit(2)
for opt,arg in opts:
if opt in ("-h","--help"):
usage()
sys.exit()
elif opt in ("-i","--input"):
if os.path.isfile(arg):
local_file = arg
else:
logprint("Error: input file '%s' not found" % arg)
print("Error: input file '%s' not found" % arg)
usage()
sys.exit(2)
elif opt in ("-b","--broker"):
if os.path.isfile(arg):
mqtt_file = arg
else:
logprint("Error: broker file '%s' not found" % arg)
print("Error: broker file '%s' not found" % arg)
usage()
sys.exit(2)
elif opt in ("--debug"):
debug_flag = True
if local_file == "" or mqtt_file == "":
logprint("Error: must specify an input file and a broker file")
print("Error: must specify an input file and a broker file")
usage()
sys.exit(2)
return local_file,mqtt_file,debug_flag
def on_modified(event):
# Watchdog function.
#
# Make sure the directory has a file "prediction.txt" in it
# If it does,return the full pathname and the directory name
# Otherwise,we don't care
if event.is_directory:
pathname = event.src_path
logprint("Directory",pathname,"modified")
if os.path.isfile(pathname + '/prediction.txt'):
pathname = event.src_path
dirname = pathname.split('/')[-1]
do_stuff([pathname])
def on_created(event):
# Watchdog function.
#
# Make sure the directory has a file "prediction.txt" in it
# If it does,"created")
if os.path.isfile(pathname + '/prediction.txt'):
pathname = event.src_path
dirname = pathname.split('/')[-1]
do_stuff([pathname])
def do_stuff(directories):
global datapoints
for d in directories:
event_id = d.split("/")[-1].replace("-","")
# logprint(d," ",event_id)
json_data,count,score = read_json_file(d + '/prediction.txt')
# Only publish events above a minimum score threshold.
if score > score_THRESHOLD:
the_stats_JSON_object = parse_json(json_data,event_id,count)
try:
image_size,imagebytes,image_string = get_image(d + '/image.jpg')
except:
image_na = './image_not_available.jpg'
logprint("File %s not found. Using %s instead." % \
(d + '/image.jpg',image_na))
image_size,image_string = get_image(image_na)
datapoints = datapoints[:-1]
megastring = create_megastring(the_stats_JSON_object,image_string)
# print("MEGASTRING: ",megastring)
publishDData(mqttClient);
logprint("*****");
def do_nothing_forever():
while(True):
sleep(3600)
if __name__ == '__main__':
local_file,debug_flag = parse_cmdline(sys.argv[1:])
logprint("\n=====\nStarted %s on %s" % (sys.argv[0],datetime.Now()))
mq_groupid,mq_device = setup_local(local_file)
mq_nodename = set_nodename()
mqttClient = setup_mqtt(mqtt_file)
if mqttClient == None:
do_nothing_forever()
interval = set_interval()
homedir = os.environ['HOME']
logpath = homedir + '/apps/xxxxx'
patterns = "20*"
ignore_patterns = ""
ignore_directories = False
case_sensitive = True
my_event_handler = PatternMatchingEventHandler(
patterns,ignore_patterns,ignore_directories,case_sensitive)
my_event_handler.on_created = on_created
my_event_handler.on_modified = on_modified
observer = PollingObserver()
logprint("Scheduled observer for path " + logpath + \
" and pattern '" + patterns + "'")
o = observer.schedule(my_event_handler,logpath,recursive=True)
# logprint("Observer is watching " + o.path + " and recursive is " + o.recursive)
logprint("Observer is watching " + o.path)
observer.start()
try:
while(True):
sleep(1)
mqttClient.loop()
except KeyboardInterrupt:
logprint("Stopped",sys.argv[0],"gracefully")
observer.stop()
observer.join()
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