Cleo (Apr 08 2009)


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Message boards : Technical News : Cleo (Apr 08 2009)

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Profile Matt Lebofsky
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Message 883493 - Posted: 8 Apr 2009, 20:00:28 UTC

The science database choked last night. Nothing terrible - it was just unable to deal with the pulse index rebuilds as well as the usual outage recovery. So the assimilators got a little hung up for a while until the current index build was finished. It's still a mystery why this was as big an issue as it was - we've built indexes before on live, fully functional databases. Hmm. Apparently we have to be a little less cavalier about it.

Turning off a server for good always has unintended consequences. Shutting down milkyway yesterday caused mail from the web server to fail. A couple red herrings later I found the problem - the milkyway mail server replacement (clarke) wasn't configured to allow relaying from the web server machine. Easy squeezy problem to fix. Now reset password requests, forum moderation notices, private message alerts, etc. are being sent.

Spent way too much time hunting down the cause of a seg fault in my NTPCker web page code. It's kinda hard when it's a C program that's being executed within a c-shell script, which in turn is being called by a php script, and which is all running under apache. It's frustrating when everything works on a command line, but not within apache. Anyway I finally figured it out, or at least got it working. The irony is this code was to produce a tiny close-up waterfall plot around any given signal (to immediately spot symptoms of RFI), and once it was running Jeff and I realized our database query logic was slightly wrong, and the correct logic would take too long to be of any use in a dynamically generated plot on the web anyway. Sigh. Looks like we'll have to batch job it or something like that.

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Message 883585 - Posted: 9 Apr 2009, 0:28:13 UTC - in response to Message 883493.

Having an approximation (plot) on the web would be fine, unless you want a table of values. Then, you're right: do the query offline and later have results on the web just read answers from a summary table.

Profile [KWSN]John Galt 007
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Message 883613 - Posted: 9 Apr 2009, 2:22:55 UTC

That dang clarke...gave me problems also...

More of the noise and power requirement type...

Glad to see the old boy up and running!!!
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Message 885131 - Posted: 13 Apr 2009, 22:42:39 UTC
Last modified: 13 Apr 2009, 22:43:30 UTC

Query - if the pulse database is re-built, why does the Science page state that there's been -506m pulses in the last 24 hrs?
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Message 885284 - Posted: 14 Apr 2009, 10:18:10 UTC - in response to Message 885131.

Query - if the pulse database is re-built, why does the Science page state that there's been -506m pulses in the last 24 hrs?


Maybe ET(s) stole all the pulses to try to stop us finding him/her/it/them.

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Message 885715 - Posted: 16 Apr 2009, 3:23:24 UTC - in response to Message 883493.

Matt, are you making any use of memcached?

Read-caching queries is one of its excellent uses. If you have a lot of cacheable queries, you may be able to drastically reduce QPS on the database. If you give that query an hour lifetime, then it'll behave like an offline query with an occasional unlucky person having to wait a few more seconds for the result.
The cache memory can be automatically distributed among available servers too.

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Message 885826 - Posted: 16 Apr 2009, 16:35:18 UTC

I am guessing that Matt is taking a week of vacation.
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Message 885844 - Posted: 16 Apr 2009, 17:33:30 UTC - in response to Message 885826.

So it would seem...
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Message 885872 - Posted: 16 Apr 2009, 19:18:23 UTC
Last modified: 16 Apr 2009, 19:18:51 UTC

A well earned vacation.
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Message boards : Technical News : Cleo (Apr 08 2009)

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