I did set the LCB_LOGLEVEL to 5 and change the libcouchbase to 2.4.0 again,
but unfortunately  uwsgi hide the debug output of the liccouchbase. And I
got a lot "*[err] evmap.c:401: Assertion ctx failed in evmap_io_active* "
this cycle. I wonder if there are some other methods to get the
libcouchbase debug output just like a log file or others.


2014-07-18 0:40 GMT+08:00 Mark Nunberg <[email protected]>:

> Unfortunately I am not very well versed in uwsgi, however from from what I
> see, you are instantiating the Connection object in global scope.
> Presumably the Category.on_post method is called inside the workers which
> are already spawned once the application has been loaded (inheriting the
> Connection object). This may lead to unwanted behavior, ranging from data
> corruption to random crashes.
>
> The crashes you are seeing seem to be coming from libevent which is
> obviously not happy about being forked (in the 2.4.0 client). The 2.3.x
> client crashes because it is receiving garbage data from the socket (since
> you have multiple processes reading from the same socket).
>
> Please set LCB_LOGLEVEL=5 in the environment before spawning your program.
> This will show a lot of debug output about the client library (continue
> using 2.4 for this); the output will tell us if you are actually trying to
> use the same client from multiple processes.
> If indeed this is the case you will need to figure out a way to ensure
> that the client object is never inherited from a parent to a child process.
> There is the Python `atfork` (https://pypi.python.org/pypi/atfork/0.1.2)
> module which you can use to help with this.
>
> Regards,
> Mark
>
> On Jul 17, 2014, at 9:31 AM, 孙如镇 <[email protected]> wrote:
>
> 33 keys were used by get_multi, my uwsgi command is "*sudo uwsgi -s
> /tmp/uwsgi.sock  --wsgi-file api.py --callable app --master --process 4  -R
> 10000", *I didn't use threads.
>
>
> 2014-07-18 0:24 GMT+08:00 Mark Nunberg <[email protected]>:
>
>> Just how many keys are you passing to get_multi/set_multi?
>>
>> Mentioning uwsgi, what form of thread/process configuration are you
>> using? Keep in mind that in the case of forking, you must ensure the
>> Connection object is create in the child process, not the parent process.
>>
>> On Jul 17, 2014, at 9:19 AM, 孙如镇 <[email protected]> wrote:
>>
>> Hi Nunberg,
>>
>>      My libcouchbase-dev is 2.3.2. I have tried to use your
>> libcouchbase-dev 2.4.0, but situation even be much worsen.A lot "
>> *timeout*" were throw out,but no *"src/server.c:666:
>> lcb_server_purge_implicit_responses: Assertion `c->cmd_log.nbytes' failed."*
>> errors. Now I am sure that the error " *src/server.c:666:
>> lcb_server_purge_implicit_responses: Assertion `c->cmd_log.nbytes' failed.*"
>> makes my python application container(uwsgi) down before. By the way some
>> time another error *"evmap.c:401: Assertion ctx failed in
>> evmap_io_active*", So really need your help.
>>
>> Best regards.
>>
>>
>> 2014-07-17 22:52 GMT+08:00 孙如镇 <[email protected]>:
>>
>>> Hi Nunberg,
>>>
>>>      Thanks for your replay. I will follow you advices and do some
>>> experiments.
>>>
>>> Best regards.
>>>
>>>
>>> 2014-07-17 22:42 GMT+08:00 M. Nunberg <[email protected]>:
>>>
>>> Hi
>>>>
>>>> Such errors would fall under the domain of the underlying libcouchbase.
>>>> What version of libcouchbase are you using? Version 2.3.1 and earlier has a
>>>> bug which may manifest itself in the symptom you are describing, so please
>>>> try 2.3.2 (http://www.couchbase.com/communities/c-client-library)
>>>>
>>>> I would also suggest you try to run your tests with the new 2.4.0-beta
>>>> version to see how that goes. Get it here
>>>> http://packages.couchbase.com/clients/c/index.html
>>>>
>>>>
>>>> On 07/17/2014 04:23 AM, Chen Sun wrote:
>>>>
>>>>> I am a new guy to couchbase.I try to use couchbase and couchbase's
>>>>> python client in my python-base web APIs.But I find some errors when I
>>>>> use ab(a tool to test the web api performence) to test the api with
>>>>> some
>>>>> concurrecny http requests. The errors of the python clinet throwed
>>>>> bellow here.I want know why these errors occoured,and how to solve this
>>>>> problem.
>>>>>
>>>>> The errors
>>>>> ------------------------------------------------------------
>>>>> ---------------------------------------------------------------
>>>>>
>>>>> uwsgi: src/server.c:666: lcb_server_purge_implicit_responses:
>>>>> Assertion `c->cmd_log.nbytes' failed.
>>>>> python-couchbase: self->nremaining == 0 at src/oputil.c:77.
>>>>> AbortTraceback (most recent call last):
>>>>>    File "api.py", line 111, in falcon.api.API.__call__
>>>>> (falcon/api.c:1389)
>>>>>      #                                             startkey=start,
>>>>> endkey=end,
>>>>>    File "api.py", line 96, in falcon.api.API.__call__
>>>>> (falcon/api.c:1210)
>>>>>      #                 end = '/' + adid + '/' + end
>>>>>    File "api.py", line 174, in on_post
>>>>>      query_results = couchbase_category.get_multi(keys, quiet=True)
>>>>>    File "/usr/local/lib/python2.7/dist-packages/couchbase/connection.py",
>>>>> line 1053, in get_multi
>>>>>      return _Base.get_multi(self, keys, ttl=ttl, quiet=quiet,
>>>>> replica=replica, no_format=no_format)
>>>>> couchbase.exceptions._TimeoutError_0x17 (generated, catch
>>>>> TimeoutError): <Key=u'com.htc.fm', RC=0x17[Client-Side timeout
>>>>> exceeded for operation. Inspect network conditions or increase the
>>>>> timeout], Operational Error, Results=34, C Source=(src/multiresult.c,286)
>>>>> >
>>>>>
>>>>> ------------------------------------------------------------
>>>>> ------------------------------------------------------------
>>>>> ------------
>>>>>
>>>>> My python code
>>>>>
>>>>> couchbase_category=  Couchbase.connect(
>>>>>
>>>>>              bucket='Category',  host='127.0.0.1',  timeout=5)
>>>>> class  Category:
>>>>>
>>>>>      def  on_post(self,  req,  resp):
>>>>>
>>>>>          t1=  datetime.datetime.now()
>>>>>          content=  {}
>>>>>          # try:
>>>>>          params=  json.load(req.stream,  'utf-8')
>>>>>          keys=  []
>>>>>          for  appin  params['apps']:
>>>>>
>>>>>              keys.append(app['bundle_id'])
>>>>>
>>>>>          unknown_apps=  []
>>>>>          result=  {}
>>>>>          result['known_bundle_ids']  =  []
>>>>>          result['unknown_bundle_ids']  =  []
>>>>>          result['apps']  =  []
>>>>>          result['categorys']  =  []
>>>>>
>>>>>          query_results=  couchbase_category.get_multi(keys,
>>>>>  quiet=True)
>>>>>          for  keyin  query_results:
>>>>>
>>>>>              if  query_results[key].success:
>>>>>                  result['apps'].append(query_results[key].value)
>>>>>                  result['known_bundle_ids'].append(key)
>>>>>                  result['categorys'].append(
>>>>>                      query_results[key].value['categoryName'])
>>>>>              else:
>>>>>                  result['unknown_bundle_ids'].append(key)
>>>>>          result['categorys']  =  list(set(result['categorys']))
>>>>>          for  itemin  params['apps']:
>>>>>
>>>>>              if  item['bundle_id']  in  result['unknown_bundle_ids']:
>>>>>                  unknown_apps.append(item)
>>>>>          timestamp=  time.time()
>>>>>          pipe=  r.pipeline()
>>>>>          for  appin  unknown_apps:
>>>>>
>>>>>              pipe.zadd('uncached_apps',  timestamp,  app)
>>>>>          pipe.execute()
>>>>>          content['is_ok']  =  True
>>>>>          content['result']  =  result
>>>>>          t2=  datetime.datetime.now()
>>>>>
>>>>>          content['total_time']  =  (t2 - t1).total_seconds()
>>>>>          # except Exception, err:
>>>>>       #   content['is_ok'] = False
>>>>>          # finally:
>>>>>          resp.status  =  falcon.HTTP_201
>>>>>          resp.body  =  json.dumps(content)
>>>>>
>>>>>
>>>>> --
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>>>>>
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>>>
>>>
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