As described in an earlier email to this list, we've got a problem with our installation of Fuseki 3.4.0(*) where it goes into a state of very high CPU usage, and load average climbs to high levels, leading to the database becoming unresponsive. We've managed to extract some stats on queries when this happens, and while we haven't been able to draw any conclusions on why it happens, we have spotted one odd thing.
We've got a server-wide timeout setting of "20000,40000". When the server is behaving, almost all queries are answered within 100ms. When it's not, we see queries running for much, much longer - in some cases, up to almost 6 minutes. This would seem to be something of a mismatch with the timeout settings. I would expect to see a bunch of queries being killed at shortly after 20s, and a bunch being killed at shortly after 40s, and nothing beyond that point. Why is Fuseki ignoring the timeout settings we've given it? Is there a parameter that can be passed to Fuseki (an HTTP header?) which overrides the default timeouts? Have we simply misunderstood what the timeout setting in the server config file does? Thanks, Hugo. (*) We're running 3.4.0 because when we tried a later version, the application failed even more often than it does right now. I don't know if the failure mode was the same as this one - that predates this current investigation by a year or more, and I wasn't involved in that. Hugo Mills Development Team Leader agrimetrics.co.uk Reading Enterprise Centre, Whiteknights Road, Reading, UK, RG6 6BU
