On Jun 22, 2009, at 11:06 AM, Andreas Jung wrote:

> On 22.06.09 16:56, Pedro Ferreira wrote:
>> Hello all,
>> We occasionally get some messages like this in the logs:
>> 2009-06-22T14:12:42 (30651/ Transaction blocked
>> waiting for storage. Clients waiting: 1.
>> But today we eventually got to:
>> 2009-06-22T16:00:11 (30651/ Transaction blocked
>> waiting for storage. Clients waiting: 204.
>> Which lasted some minutes.  During that time, our system seemed to  
>> hang,
>> even if it was possible to connect to the db through the command  
>> line.
>> It eventually went back to normal by itself.
>> Any clue on what might have caused this?
> The reason is likely a long running transaction. Since the storage  
> server
> is single-threaded, a long running transaction will block pending  
> requests.

No, the storage server is only blocked in the very last stage of a two- 
phase commit, not for the entire duration of the transaction.


Jim Fulton
Zope Corporation

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