[ZODB-Dev] blocked transactions?

[Chris Withers]

On 13/10/2010 15:23, Jim Fulton wrote:
>> Their occurences coincided with an app server cluster of 4 clients locking
>> up completely...
>
> Did the numbers get much bigger than 3?

Nope.

>> I would dearly love to know why that happened.
>
> Typically, it's due to a client that votes and fails to call finish.

Wouldn't I see storage errors in that case?
The only errors I saw were these and quite a few:

   File 
"/var/buildout-eggs/ZODB3-3.9.6-py2.6-linux-i686.egg/ZEO/ServerStub.py", 
line 377, in stub
     raise ValueError("Timeout waiting for protocol handshake")
ValueError: Timeout waiting for protocol handshake

>> Any way to interrogate a
>> running zeo server to find out what it thinks it's up to?
>
> You can connect to the monitor port in 3.9 and earlier,

When that's configured, what information does it provide and how do I 
get it? (if there are docs, lemme know and I'll go read them instead)

> You almost certainly want to set transaction-timeout in
> your server configuration.  This will cause transactions that take too
> long to be terminated.  We use a transaction timeout of 300 seconds.

5 mins is pretty high, though, right? Surely if all clients end up 
hanging for 230 seconds, they'll all be dropped by a load balancer?

Related: how can I find out how long transactions are taking?

cheers,

Chris

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