Is there a scheduled downtime for DBpedia, or did I just pick an unfortunate time to ask it about hockey? Both my code and my browser at getting 503's at the moment, where they weren't 10 minutes ago.

asked 09 May '11, 13:50

Ryan%20Kohl's gravatar image

Ryan Kohl
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:( Too many people uses dbpedia as a sandbox, and some ill queries runs much longer than predicted by the compiler, causing redundand load and wasted working set. Fortunately, many important applications use private replicas of dbpedia (or whole LOD), so they does not suffer from unpredictable overloads of the public server and the public served does not suffer from quite predictable overloads of these apps :)

The scheduled downtime of DBpedia is quite minor and the cache warm-up after start is very aggressive, so the lag between server start and reaching 30-50% of the peak performance is surprisingly small. Scheduled downtimes of LOD are a bit longer (at least I've seen maintainance page on LOD myself but I've never seen it on dbpedia). The long part of LOD maintainance is free-text indexing, because both the number of graphs and the size of vocabulary are "a bit bigger" than average. dbpedia is more convenient for free-text because it's all about single graph.

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answered 09 May '11, 16:12

Ivan%20Mikhailov%201's gravatar image

Ivan Mikhail...
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edited 10 May '11, 00:41

Would you say, then, that the 503 response I saw (which was also matched by the dbpedia.org site) today was due to a scheduled downtime? I noticed the site and endpoint were back up within the hour.

(09 May '11, 16:48) Ryan Kohl Ryan%20Kohl's gravatar image

The DBpedia SPARQL endpoint was down for a scheduled binary upgrade today, as announced on twitter ...

(09 May '11, 20:59) hwilliams hwilliams's gravatar image
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@hwilliams which twitter account, for the curious and lazy ;)

(10 May '11, 03:00) Jerven ♦ Jerven's gravatar image

@Jerven: OpenLink's twitter account, perhaps: http://twitter.com/OpenLink or maybe search for hashtag #dbpedia. HTH

(10 May '11, 14:33) Tim.Haynes Tim.Haynes's gravatar image

According to Mondeca's SPARQL Endpoint Status, DBpedia has a service disruption right now (it's red). Don't know if it's scheduled.

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answered 09 May '11, 14:23

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cygri ♦
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Serves me right for not giving the Endpoint Status site more than a few minutes to detect the outage. At least I know it isn't just me now :)

(09 May '11, 14:39) Ryan Kohl Ryan%20Kohl's gravatar image

In the name of science, we recently did some experiments where we crawled a selection of URLs from different domains, each month, for nine months during 2010.

Domains were accessed twice per second. The crawler had timeouts set at 128 s for sockets, and 64 s for connecting. Crawls were done midnight between Sat/Sun.

We derived a stability score of 86% for DBpedia from 8,942 URLS, meaning that each URL from DBpedia was successfully retrieved on average, 7.74 of the 9 attempts.

47% of the URLs were retrieved in all snapshots.

Interpret those results how you will.

YMMV.

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answered 09 May '11, 14:11

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Signified ♦
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edited 09 May '11, 14:12

Unfortunately, no Doc Brown quotes come to mind.

Do you recall the distribution of http codes when you ran into failures?

(09 May '11, 14:20) Ryan Kohl Ryan%20Kohl's gravatar image
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Doing a quick grep, failures were primarily of the timeout variety, primarily connection timeouts and then read timeouts. The only error response code returned were low numbers of 500 and 503. No 4xx response codes were found.

(09 May '11, 18:31) Signified ♦ Signified's gravatar image
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question asked: 09 May '11, 13:50

question was seen: 2,355 times

last updated: 10 May '11, 14:33