问题
I am trying to read meta info from celery task in case of timeout (if task is not finished in given time). I have 3 celery workers. When I execute tasks on 3 workers serially my timeout logic (getting meta info from redis backend) works fine. But, when I execute tasks in parallel using threads, I get error 'AttributeError: 'DisabledBackend' object has no attribute '_get_task_meta_for''.
main script.
from threading import Thread
from util.tasks import app
from celery.exceptions import TimeoutError
# from celery.task.control import revoke
from celery.result import AsyncResult
def run(cmd, workerName, async=False, timeout=9999999):
print "Executing Celery cmd: ", cmd
ret = app.send_task(workerName+'.run_cmd', args=[cmd], kwargs={}, queue=workerName)
if async:
return ret
else:
try:
return ret.get(timeout=timeout)
except TimeoutError:
task = AsyncResult(ret.task_id)
# print task.info
out = task.info['PROGRESS']
# stop_task(ret.task_id)
print 'TIMEOUT', out
return 'TIMEOUT', out
cmd = r'ping 10.10.10.10'
threads = []
# this block works
print "This block works"
run(cmd, 'MH_VTF203', timeout=10)
run(cmd, 'MH_VTF1661', timeout=10)
run(cmd, 'MH_VTF106', timeout=10)
# this block errors
print "This block erros"
for vtf in ['MH_VTF203', 'MH_VTF1661', 'MH_VTF106']:
t = Thread(target=run, args=[cmd, vtf], kwargs={'timeout': 10})
t.start()
threads.append(t)
for t in threads:
t.join()
util.tasks.py
from celery import Celery
import subprocess
app = Celery('tasks', backend='redis://', broker='redis://localhost:6379/0')
app.conf.CELERY_IGNORE_RESULT = False
app.conf.CELERY_RESULT_BACKEND = 'redis://localhost:6379/0'
@app.task()
def run_cmd(*args, **kwargs):
cmd = " ".join(args)
print "executing command :",cmd
try:
p = subprocess.Popen(cmd, stdout=subprocess.PIPE, stderr=subprocess.PIPE)
out = ""
while p.poll() is None:
l = p.stdout.readline()
print l
out += l
run_cmd.update_state(
state='PROGRESS',
meta={'PROGRESS': out}
)
l = p.stdout.read()
print l
out += l
return out
except subprocess.CalledProcessError, e:
print 'Error executing command: ', cmd
return str(e)
Output.
C:\Python27\python.exe C:/Users/mkr/Documents/work/New_RoD/testing/run.py
This block works
Executing Celery cmd: ping 10.10.10.10
TIMEOUT
Pinging 10.10.10.10 with 32 bytes of data:
Request timed out.
Request timed out.
Executing Celery cmd: ping 10.10.10.10
TIMEOUT
Pinging 10.10.10.10 with 32 bytes of data:
Request timed out.
Request timed out.
Executing Celery cmd: ping 10.10.10.10
TIMEOUT
Pinging 10.10.10.10 with 32 bytes of data:
Request timed out.
Request timed out.
This block erros
Executing Celery cmd: ping 10.10.10.10
Executing Celery cmd: ping 10.10.10.10
Executing Celery cmd: ping 10.10.10.10
Exception in thread Thread-1:
Traceback (most recent call last):
File "C:\Python27\lib\threading.py", line 810, in __bootstrap_inner
self.run()
File "C:\Python27\lib\threading.py", line 763, in run
self.__target(*self.__args, **self.__kwargs)
File "C:/Users/mkr/Documents/work/New_RoD/testing/run.py", line 18, in run
out = task.info['PROGRESS']
File "C:\Python27\lib\site-packages\celery\result.py", line 356, in result
return self._get_task_meta()['result']
File "C:\Python27\lib\site-packages\celery\result.py", line 339, in _get_task_meta
return self._maybe_set_cache(self.backend.get_task_meta(self.id))
File "C:\Python27\lib\site-packages\celery\backends\base.py", line 292, in get_task_meta
meta = self._get_task_meta_for(task_id)
AttributeError: 'DisabledBackend' object has no attribute '_get_task_meta_for'
Exception in thread Thread-2:
Traceback (most recent call last):
File "C:\Python27\lib\threading.py", line 810, in __bootstrap_inner
self.run()
File "C:\Python27\lib\threading.py", line 763, in run
self.__target(*self.__args, **self.__kwargs)
File "C:/Users/mkr/Documents/work/New_RoD/testing/run.py", line 18, in run
out = task.info['PROGRESS']
File "C:\Python27\lib\site-packages\celery\result.py", line 356, in result
return self._get_task_meta()['result']
File "C:\Python27\lib\site-packages\celery\result.py", line 339, in _get_task_meta
return self._maybe_set_cache(self.backend.get_task_meta(self.id))
File "C:\Python27\lib\site-packages\celery\backends\base.py", line 292, in get_task_meta
meta = self._get_task_meta_for(task_id)
AttributeError: 'DisabledBackend' object has no attribute '_get_task_meta_for'
Exception in thread Thread-3:
Traceback (most recent call last):
File "C:\Python27\lib\threading.py", line 810, in __bootstrap_inner
self.run()
File "C:\Python27\lib\threading.py", line 763, in run
self.__target(*self.__args, **self.__kwargs)
File "C:/Users/mkr/Documents/work/New_RoD/testing/run.py", line 18, in run
out = task.info['PROGRESS']
File "C:\Python27\lib\site-packages\celery\result.py", line 356, in result
return self._get_task_meta()['result']
File "C:\Python27\lib\site-packages\celery\result.py", line 339, in _get_task_meta
return self._maybe_set_cache(self.backend.get_task_meta(self.id))
File "C:\Python27\lib\site-packages\celery\backends\base.py", line 292, in get_task_meta
meta = self._get_task_meta_for(task_id)
AttributeError: 'DisabledBackend' object has no attribute '_get_task_meta_for'
Process finished with exit code 0
回答1:
using app.AsyncResult worked for me
回答2:
Celery operations are not thread safe - you probably want to wrap the call to task.info in a lock.
Also mixing celery and threads like that is a little odd.
来源：https://stackoverflow.com/questions/31098547/attributeerror-disabledbackend-object-has-no-attribute-get-task-meta-for