Re: strange exception

My zope application is a multi-node application. Each node has two 
databases.
- One local file based database for some local storage. This does not 
create any exception. 
- One centralised database running on ZEO. (For this I maintain one global 
database connection across all threads). This connection is protected by a 
global lock.

Same thread can make changes in both databases, but in separate 
transactions. Application does not cause any consistency issues because 
both databases have independent information from each other.

When I keep number of threads about 15 then exception was not observed, but 
if i increase number of threads to 30 then it was observed consistently. 
Once this exception occurs then it keep happening until not restarted.

Do you need some more information to understand ?

On Thursday, 22 December 2016 20:42:35 UTC+5:30, Jim Fulton wrote:
>
>
>
> On Thu, Dec 22, 2016 at 4:25 AM, Sanjay Rao <[email protected] 
> <javascript:>> wrote:
>
>> Does anyone has any idea that in what conditions this exception can occur 
>> ?
>>
>
> Not really. I don't recall ever seeing this. An off-hand guess would be 
> some sort of threading or (given your follow-up message) perhaps a 
> process-contention issue of some sort.
>
> Please describe your setup, especially how you're using processes and 
> threads.
>
> Jim
>  
>
>>
>>   File "C:\Python27\lib\site-packages\zope\app\component\hooks.py", line 
>> 89, in getSiteManager
>>     context, zope.component.getGlobalSiteManager())
>>   File "C:\Python27\lib\site-packages\zope\app\component\hooks.py", line 
>> 95, in adapter_hook
>>     return siteinfo.adapter_hook(interface, object, name, default)
>>   File "C:\Python27\lib\site-packages\zope\app\component\site.py", line 
>> 407, in SiteManagerAdapter
>>     current = getattr(current, '__parent__', None)
>>   File 
>> "C:\Python27\lib\site-packages\zodb-4.4.3-py2.7.egg\ZODB\Connection.py", 
>> line 899, in setstate
>>     self._setstate(obj, oid)
>>   File 
>> "C:\Python27\lib\site-packages\zodb-4.4.3-py2.7.egg\ZODB\Connection.py", 
>> line 943, in _setstate
>>     p, serial = self._storage.load(oid, '')
>>   File 
>> "C:\Python27\lib\site-packages\zeo-4.3.0-py2.7.egg\ZEO\ClientStorage.py", 
>> line 825, in load
>>     result = self.loadBefore(oid, m64)
>>   File 
>> "C:\Python27\lib\site-packages\zeo-4.3.0-py2.7.egg\ZEO\ClientStorage.py", 
>> line 851, in loadBefore
>>     self._cache.store(oid, tid, end, data)
>>   File "C:\Python27\lib\site-packages\zeo-4.3.0-py2.7.egg\ZEO\cache.py", 
>> line 139, in _locked_wrapper
>>     return func(inst, *args, **kwargs)
>>   File "C:\Python27\lib\site-packages\zeo-4.3.0-py2.7.egg\ZEO\cache.py", 
>> line 647, in store
>>     self._store(oid, start_tid, end_tid, data, size)
>>   File "C:\Python27\lib\site-packages\zeo-4.3.0-py2.7.egg\ZEO\cache.py", 
>> line 661, in _store
>>     nfreebytes = self._makeroom(size+1)
>>   File "C:\Python27\lib\site-packages\zeo-4.3.0-py2.7.egg\ZEO\cache.py", 
>> line 447, in _makeroom
>>     del current[oid]
>>   File 
>> "C:\Python27\lib\site-packages\zodb-4.4.3-py2.7.egg\ZODB\fsIndex.py", 
>> line 167, in __delitem__
>>     del tree[key[6:]]
>> KeyError: '_\t'
>>
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>
>
>
> -- 
> Jim Fulton
> http://jimfulton.info
>

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