Wikitech-l May 2002

wikitech-l@lists.wikimedia.org

22 participants
89 discussions

New server specs
by Jimmy Wales 16 May '02

16 May '02

Tyan S2462 motherboard with Dual AMD Athlon MP 1800+/266FSB 2 GB of ECC Reg. DDR-266/PC2100 ram (4 - 512 Mb pieces) IBM 36 GB Ultra 160 / 10 K RPM Dual onboard 3Com 10/100 adapters For the install, we'll go with MySQL 4.0 unless someone gives us a good reason not to do it -- this will enable us to cut the minimum keyword length in the search engine down to less than 4. We'll probably install the latest stable Kernel at the time we get the machine, 2.4.18 right now. I'm tempted to go with Apache 2.0.36, but I've haven't used Apache 2.x in production, so maybe we won't start with that. Opinions welcome. This should be a pretty sweet setup. The new server will host Wikipedia and Nupedia ONLY. --Jimbo

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New server
by Jimmy Wales 16 May '02

16 May '02

Good news! I'm buying Wikipedia a new and much more powerful server. Bomis.com needs a new server in our web cluster. As it turns out, ross.bomis.com (the current wikipedia server) is physically identical to our existing servers in our web cluster (because I bought ross at the same time), and is therefore ideal to include in the web cluster without complicating my load balancing over there. This means that the newly purchased server, which should be here in a couple of weeks, will be set up exclusively for wikipedia. I will be moving personal websites of mine (like jimmywales.com and kirawales.com) and experimental websites of mine OFF this machine, but not to the new machine. The new machine will be setup with different root password, and no real connection to the rest of my network. This means that I can give developers Unix shell accounts on the machine, and even the root password in some cases. The new machine will be a dual Athlon with 2 gig of ram and a much bigger SCSI harddrive than what we have now. The performance of the machine should be a lot better than the existing single PIII with 1 gig of ram. This will all come to pass in the next couple of weeks. This will remove me as a key bottleneck in the development/release cycle. --Jimbo

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AW: Re: (from [Wikipedia-l]) speed at last
by Magnus Manske 16 May '02

16 May '02

-- Original Nachricht -- >Gareth Owen wrote: >> >> Karen AKA Kajikit <kaji(a)labyrinth.net.au> writes: >> >> > Lars Aronsson wrote: >> >> I don't know what caused this, but I love it. >> >> Now I can start to promote Wikipedia more actively. >> > >> > It's good isn't it! >> >> I'm glad someone's getting joy. I'm timing out 4 times out of 5... > >I said it WAS good... alas it seems to have ground to a halt again. I >went from rapid access to all pages to no access at all. :( I had similar experiences today - either really fast, or not at all. Strangely, I had a fast page, a link from there (in a new window) timed out, and another one (started some seconds later) was fast again. The only explanation I can come up with is that some requests go to a slow thread/process, which would match with the "really big process" bug we encountered some time ago. Jimbos top-dump showed a zombie process, which was probably it. Is there a way we can find out if the bad process starts only on certain pages (e.g., the Most Wanted), or if it just happens at random? That would help enormously in error search. Magnus ________________________________________ Zeitschriftenabos online bestellen - jetzt neu im Infoboten! http://www.epost.de

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speed at last
by Lars Aronsson 16 May '02

16 May '02

Since 21:00 GMT (2 pm PDT) Wednesday, Wikipedia is really fast: - Static images load in less than one second. - Wiki pages load in 5 seconds (often less than 2). - Recent Changes loads in 5 seconds in 86% of my samples. - No responses ever take longer than 15 seconds. I don't know what caused this, but I love it. Now I can start to promote Wikipedia more actively. Note that I'm in Sweden and the server is in San Diego, and the single roundtrip time (ping) alone accounts for 0.25 seconds. Theoretically (speed of light, size of Earth), this could be reduced to 0.10 seconds. Starting "wget", opening a socket (one roundtrip), sending a request, and receiving a response (second roundtrip) containing the Wikipedia logotype, all in 0.70 seconds is pretty amazing. It never took longer than 0.91 seconds in the last 14 hours. -- Lars Aronsson <lars(a)aronsson.se> tel +46-70-7891609 http://aronsson.se/ http://elektrosmog.nu/ http://susning.nu/

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the bug bug
by Lars Aronsson 16 May '02

16 May '02

>From http://meta.wikipedia.com/wiki.phtml, the link for reporting bugs goes to a page gets hooked up in some redirect loop, http://wikipedia.sourceforge.net/fpw/wiki.phtml?title=wikipedia%3ABugs The displayed text says: You are being redirected to wikipedia.com Warning: Cannot add header information - headers already sent by (output started at /home/groups/w/wi/wikipedia/htdocs/fpw/wiki.phtml:5) in /home/groups/w/wi/wikipedia/htdocs/fpw/wiki.phtml on line 81 -- Lars Aronsson <lars(a)aronsson.se> tel +46-70-7891609 http://aronsson.se/ http://elektrosmog.nu/ http://susning.nu/

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Link to non-existing pages
by Jens Frank 15 May '02

15 May '02

Hello, I just clicked a red link (indicating that there currently is no article yet). The link triggered had a &action=edit -suffix and thus invoked the new page in edit-mode. The only problem was that in the meantime, just after the page was put to the pagecache, the article has been written. So I ended with the edit-mode of a quite fine article. While this is probably OK for a wikipedia contributor I think this might be confusing for a "user". I would like to ask whether it might make sense to change the URL invoked by red links to not end in "&action=edit". Then the automatic edit-mode for non-existent articles is triggered in case of a non-existing article and for articles written in the meantime the link would just show the article expected. Best Regards, jens frank

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response times
by Lars Aronsson 15 May '02

15 May '02

I'm looking again at my log files, comparing three days: - Thursday May 9, before Jimmy's change (old talk links) - Friday May 10, after Jimmy's change (no talk links) - Tuesday May 14, with the new version (new talk links) The overall performance was best on Friday. It is now getting worse again, albeit not as bad as Thursday. The new version is a real improvement over the old talk links, but we aren't quite done yet. The number of OK responses (HTTP status code 200) which take absurdly long (longer than 60 seconds) is still very high (3-30 %), with the Main Page of the English Wikipedia being the main exception (0 %). Response times above some limit (say, 30, 60 or 120 seconds) can be defined as absurdly long, because the user will have left for other websites and is no longer waiting for the response. Instead of spending more system resources (CPU cycles and allocated memory) on these requests, it would be better to set a hard time out (in PHP or Apache) and return an error message that says "sorry for the delay". This would free up system resources that can be better used to serve other requests. In <http://www.php.net/manual/en/function.set-time-limit.php>, the PHP function set_time_limit() is said to have a default of 30 seconds, unless the configuration file has defined max_execution_time. Will calling this function set the time limit for the current request only, or set a permanent value for the server? What happens when PHP execution times out? Is the connection to the client abruptly closed? Or is an error message returned? Does an error message appear in the log file? I haven't seen any timeouts of this kind. However, even if a PHP execution timeout is set, the limit will not include time that the request spent waiting to start execution. This wait could happen in the UNIX socket listen backlog, waiting for the connection to be accepted, or inside Apache, waiting for a child process to become available. Increasing the value of a parameter like ListenBacklog (in Apache httpd.conf) is not necessarily a solution, because this will only keep more requests in queue, increasing overall response time. Instead, the problem should be fixed at the exit end of the queue. The key to better performance is keeping the server fast and queues short, getting things done. Here are some pages on Apache performance issues: - Hints on Running a High-Performance Web Server, http://httpd.apache.org/docs/misc/perf.html - Apache Performance Notes, http://httpd.apache.org/docs/misc/perf-tuning.html - Professional Apache, chapter 8, http://www.devshed.com/Talk/Books/ProApache/ - Tuning Your Apache Web Server, http://dcb.sun.com/practices/howtos/tuning_apache.jsp - Linux HTTP Benchmarking HOWTO, http://www.xenoclast.org/doc/benchmark/HTTP-benchmarking-HOWTO/ -- Lars Aronsson (lars(a)aronsson.se) Aronsson Datateknik Teknikringen 1e, SE-583 30 Linuxköping, Sweden tel +46-70-7891609 http://aronsson.se/ http://elektrosmog.nu/ http://susning.nu/

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"Really big process bug"?
by Axel Boldt 15 May '02

15 May '02

> Anyway, currently the 'pedia seems to run fast and stable. I have been seeing several fast accesses and every once in a while an extremely slow one. It could be that one of the special functions (or search?) behaves badly. > Is the "really big process" bug back?? What is the "really big process" bug? I have been wondering before whether it's possible to have memory leaks in php scripts: is everything automatically released once the page is served? Somebody somewhere could be eating memory, and that would slow everything. If memory is indeed the bottleneck, then caching might not be a good idea, since we in effect transport twice as much data between database and php script, and I would expect that the data is buffered in memory on both ends. Some top/ps outputs would really help. Axel

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Re: Link update script
by Brion Vibber 15 May '02

15 May '02

Tisdag, 14 Maj 2002, Jimmy Wales skribte: > I've switched to the CVS version and corrected a few bugs. But the > site is sluggish again, and load is creeping upward. I wonder if > getOtherNamespaces is the issue again? It could be the temporary workaround I had put in place for the certain-common-words-cause-searches-to-fail-completely bug, which falls back to a slow but reliable LIKE search when the MATCH fails. I've disabled the fallback in CVS; update special_dosearch.php and see if performance (if not search results) improves. The search system needs some major work, alas... -- brion vibber (brion @ pobox.com)

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Fixes to watchlist
by Brion L. VIBBER 15 May '02

15 May '02

I've just checked in a rewrite of the watchlist function; instead of doing a zillion separate database queries, it now does just two: one to get the watchlist from the user table, the other to grab the info needed to fill out the table/list. Please, check over it and make sure it looks okay before we let yet another horribly misshappen watchlist version wander over the land! As a hack to get non-blank, non-talk namespaces listed until we have a separate field that contains the title but *not* the namespace, all valid namespaces get prepended to the titles-to-be-watched in the list given to the database to check against. I've also fixed the bug whereby clicking "add to my watchlist" on a page with a non-blank namespace results in a redirect to the equivalent title in the blank namespace. (It would also be possible, if preferred, to limit the namespace-laxity in the watchlist to just "X" and "X talk" pairs. Personally, I've seen enough pages get moved from blank to "wikipedia:" that I'd prefer to keep complete namespace agnosticism in my watchlist: the less I have to add and subtract things to keep my watchlist relevent, the better.) -- brion vibber (brion @ pobox.com)

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Wikitech-l May 2002