如何将非阻塞stderr捕获添加到线程popen-howtoaddnonblockingstderrcapturetothreadedpopen's

I've got a python 3 script i use to backup and encrypt mysqldump files and im having a particular issues with one database that is 67gb after encryption & compression. The mysqldump is outputting errorcode 3, so i'd like to catch the actual error message, as this could mean a couple of things. The random thing is the backup file is the right size, so not sure what the error means. it worked once on this database...

我有一个python 3脚本,我用来备份和加密mysqldump文件,我有一个特殊的问题,一个数据库,加密和压缩后67GB。 mysqldump正在输出错误代码3,所以我想捕获实际的错误消息,因为这可能意味着一些事情。随机的是备份文件的大小合适,所以不确定错误的含义。它在这个数据库上工作过一次......

the code looks like the below and i'd really appreciate some help on how to add non-blocking capture of stderr when the return code is anything but 0 for both p1 and p2.

代码如下所示,我非常感谢有关如何在返回代码为p1和p2的0以外的任何内容时添加非阻塞捕获stderr的一些帮助。

Also, if im doing anything glaringly obvious wrong, please do let me know, as i'd like to make sure this is a reliable process. it has been working fine on my databases under 15gb compressed.

此外,如果我做任何明显错误的事情,请告诉我,因为我想确保这是一个可靠的过程。在15gb压缩下,它在我的数据库上工作正常。

def dbbackup():
    while True:
        item = q.get()
        #build up folder structure, daily, weekly, monthy & project
        genfile = config[item]['DBName'] + '-' + dateyymmdd + '-'
        genfile += config[item]['PubKey'] + '.sql.gpg'
        if os.path.isfile(genfile):
            syslog.syslog(item + ' ' + genfile + ' exists, removing')
            os.remove(genfile)
        syslog.syslog(item + ' will be backed up as ' + genfile)
        args = ['mysqldump', '-u', config[item]['UserNm'],
                '-p' + config[item]['Passwd'], '-P', config[item]['Portnu'],
                '-h', config[item]['Server']]
        args.extend(config[item]['MyParm'].split())
        args.append(config[item]['DBName'])
        p1 = subprocess.Popen(args, stdout=subprocess.PIPE)
        p2 = subprocess.Popen(['gpg', '-o', genfile, '-r',
                               config[item]['PubKey'], '-z', '9', '--encrypt'], stdin=p1.stdout)
        p2.wait()
        if p2.returncode == 0:
            syslog.syslog(item + ' encryption successful')
        else:
            syslog.syslog(syslog.LOG_CRIT, item + ' encryption failed '+str(p2.returncode))
            p1.terminate()
        p1.wait()
        if p1.returncode == 0:
        #does some uploads of the file etc..
        else:
            syslog.syslog(syslog.LOG_CRIT, item + ' extract failed '+str(p1.returncode))
        q.task_done()


def main():
    db2backup = []
    for settingtest in config:
            db2backup.append(settingtest)
    if len(db2backup) >= 1:
        syslog.syslog('Backups started')
        for database in db2backup:
            q.put(database)
            syslog.syslog(database + ' added to backup queue')
        q.join()
        syslog.syslog('Backups finished')


q = queue.Queue()
cOnfig= configparser.ConfigParser()
config.read('backup.cfg')
backuptype = 'daily'
dateyymmdd = datetime.datetime.now().strftime('%Y%m%d')


for i in range(2):
    t = threading.Thread(target=dbbackup)
    t.daemon = True
    t.start()

if __name__ == '__main__':
    main()

1 个解决方案

#!/usr/bin/env python3
from configparser import ConfigParser
from datetime import datetime
from multiprocessing.dummy import Pool
from subprocess import Popen, PIPE

def backup_db(item, conf): # config[item] == conf
    """Run `mysqldump ... | gpg ...` command."""
    genfile = '{conf[DBName]}-{now:%Y%m%d}-{conf[PubKey]}.sql.gpg'.format(
                cOnf=conf, now=datetime.now())
    # ...
    args = ['mysqldump', '-u', conf['UserNm'], ...]
    with Popen(['gpg', ...], stdin=PIPE) as gpg, \
         Popen(args, stdout=gpg.stdin, stderr=PIPE) as db_dump:
        gpg.communicate() 
        error = db_dump.communicate()[1]
    if gpg.returncode or db_dump.returncode:
        error

def main():
    cOnfig= ConfigParser()
    with open('backup.cfg') as file: # raise exception if config is unavailable
        config.read_file(file)
    with Pool(2) as pool:
        pool.starmap(backup_db, config.items())

if __name__ == "__main__":
    main()