[ZODB-Dev] "Transaction blocked waiting for storage"

[Andreas Jung]

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 (30651/137.138.128.213:35787) Transaction blocked
> waiting for storage. Clients waiting: 1.
>
> But today we eventually got to:
>
> 2009-06-22T16:00:11 (30651/137.138.4.153:53416) 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.

-aj
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