[Zope] 3 of 4 Zope threads hanging - how to find culprit?

[Dario Lopez-Kästen]

Hello,

I am experiencing 3 of 4 of Zopes threads hanging and only being released by
restarting Zope. The threads have been hanging up to more than 78 000
seconds before we restarted the application.

We use DCOracle2 all the time, several SQL-queries for each request. Due to
the natuerw of the underlying SQL the response from the database can tale up
to 15 seconds to complete, and requests get stacked waiting for the repsonse
from the database server.

This leads to the situation that only 1 Zope-thread responds to requests.
There is no difference in the queries executed by each thread.

Any advice in how to prevent threads from locking up is appreciated, as well
as advice on how to find out why the threads lockup.

Zope 2-5-1, RedHat 7.2

DCO2 is not the latest release, but from somwhere this summer (fromCVS).

Thanks,

/dario

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Dario Lopez-Kästen, IT Systems & Services Chalmers University of Tech.