mysqldump和python子进程wait()不工作

Question

我使用了4个shell命令来导入和导出mysql

cmd1 > exports table structure 
cmd2 > exports table data 
cmd4 > imports table strcuture
cmd5 > imports table data

如果我直接在命令行上运行，下面4个命令运行得很好。每个命令都应该基于先前的cmd输出逐个执行。cmd2和cmd4可能需要一些时间，因为它是导出/导入表数据。cmd2未正确执行。我只看到空的输出文件。但是如果我直接在shell上运行，同样的命令也能正常工作。我尝试过这里给出的建议，python subprocess and mysqldump。但是得到了和以前一样的结果。

import subprocess

print("subprocess started....")

cmd1 = "mysqldump -h hostnamegoeshere -u FPS_DEV_User -pPASSWORD --single-transaction --no-data --triggers --routines novatime  --ignore-table=novatime.novatime_detail_paycom --ignore-table=novatime.novatime_schedules --ignore-table=novatime.novatime_schedules_new > /home/ec2/dba/subprocess/mysql-migration/novatime_mysqldump_so.sql 2> /home/ec2/dba/subprocess/mysql-migration/novatime_mysqldump_so_err.sql"
cmd2 = "mysqldump --host hostnamegoeshere -u FPS_DEV_User  -pPASSWORD --compress --single-transaction --no-create-info --add-locks --lock-tables --quick --disable-keys novatime > /home/ec2/dba/subprocess/mysql-migration/novatime_mysqldump_do.sql 2> /home/ec2/dba/subprocess/mysql-migration/novatime_mysqldump_do_err.sql"
cmd4 = "mysql --host hostnamegoeshere -u admin -PASSWORD -f novatime < /home/ec2/dba/subprocess/mysql-migration/novatime_mysqldump_so.sql 2> /home/ec2/dba/subprocess/mysql-migration/novatime_mysqldump_so_err.sql" 
cmd5 = "mysql --host hostnamegoeshere -u admin -PASSWORD -f novatime < /home/ec2/dba/subprocess/mysql-migration/novatime_mysqldump_do.sql 2> /home/ec2/dba/subprocess/mysql-migration/novatime_mysqldump_do.sql" 

try:
    
    print('process1')
    process1 = subprocess.Popen(cmd1,stdout=subprocess.PIPE, shell=True)

    process1.wait()
    print('process2')
    process2 = subprocess.Popen(cmd2,stdout=subprocess.PIPE, shell=True)

    process2.wait()
    print('process4')
    process4 = subprocess.Popen(cmd4,stdout=subprocess.PIPE, shell=True)

    process4.wait()
    print('process5')
    process5 = subprocess.Popen(cmd5,stdout=subprocess.PIPE, shell=True)

    process5.wait()

except:
    print('error')

Answer 1

您应该在等待之前关闭前面进程的stdout。

print('process1')
process1 = subprocess.Popen(cmd1,stdout=subprocess.PIPE, shell=True)

process1.stdout.close()
process1.wait()
print('process2')
process2 = subprocess.Popen(cmd2,stdout=subprocess.PIPE, shell=True)