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Questions and Answers : Pirates@Home Problems : Database was unavailable
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On an attempt to go directly to http://pirates.spy-hill.net/forum_thread.php?id=847, I've got a polite response Database unavailable It was 3-4 minutes ago. I've tred multiple times, the same. Instead if my logo and "Logout" button at the upper right corner, there was only "Login" button, pressing it did not allow me to log in. Then suddenly everyting was fine. What did happen? DB restart, or high load? Uptime ____________ Peter .-) ![]() | |
ID: 6730 | Rating: 0 | rate:
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I'm seeing a pattern here. We get these occasional high load conditions when the database is full of work (done or otherwise). But not when the database is empty of work (as it was recently after a long lull). | |
ID: 6742 | Rating: 0 | rate:
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Again just now, and no load this time: Database unavailable Uptime Captain's Cabin temperature monitor Cold enough :-) And: Workflow status ____________ Peter .-) ![]() | |
ID: 6756 | Rating: 0 | rate:
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To track this problem futher I've added the number of "slow" queries in the database section of the server status page. I previously didn't list this, as it was just a sum of all of them since the server was started, but now I divide by the uptime to get an average number of them per hour. We'll see how this does as we go through normal operations. | |
ID: 6763 | Rating: 0 | rate:
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I have increased the maximum number of database connections from (presumably) 100 to 150, which I hope will cut down on the number of "database unavailable" errors and load spikes. | |
ID: 6771 | Rating: 0 | rate:
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And again few times, one hour ago. CACHED 4:59 AM EST on 12 Nov 2007 (updated every 10 minutes) I can see nothing wrong among these numbers, the clue must be somewhere else. ____________ Peter .-) ![]() | |
ID: 6797 | Rating: 0 | rate:
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Just had another one. Database unavailable Unable to connect to database - please try again later Error: 1040 Too many connections ____________ Jord. Used to be a single voice that vanished in a crowd. Vague just like a distant sun when hidden by the clouds. Found a way to surface and to speak my truth aloud. Be powerful. Stand fast and proud | |
ID: 6805 | Rating: 0 | rate:
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Thank for reporting these events. I wish they were not happening, and I hoped increasing the max clients to 150 would have fixed it, but it helps to know what's happening in any case. I'll have to think more about what might help fix this. | |
ID: 6806 | Rating: 0 | rate:
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ID: 6807 | Rating: 0 | rate:
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Scott Brown wrote:
I suspect the overall status page is the culprit. Not by itself, though it does do a lot with the database, but combined with the regular load of machines constantly hitting the scheduler to ask for new work. That, in turn, is likely higher than "normal" because Pirates workunits are both short and few. I can try increasing the max clients further. I hadn't thought yet of increasing physical memory, but now I will. Thanks. ____________ -- Eric Myers "Education is not the filling of a pail, but the lighting of a fire." -- William Butler Yeats | |
ID: 6810 | Rating: 0 | rate:
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That is why I was curious about the mechanical turk addition. It looks like the database is hit everytime a CAPTCHA is completed to award credit under the current reward scheme? If that is the case, then the additional load from the turk might be enough (in addition to the normal hits rather than by itself) to push the load over the maximum when several members of the crew are typing them in. | |
ID: 6824 | Rating: 0 | rate:
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Scott Brown wrote: That is why I was curious about the mechanical turk addition. It looks like the database is hit everytime a CAPTCHA is completed to award credit under the current reward scheme? If that is the case, then the additional load from the turk might be enough (in addition to the normal hits rather than by itself) to push the load over the maximum when several members of the crew are typing them in. It's true that there is a DB hit with each CAPTCHA, but the number of people using the turk is small compared to the number of active hosts hitting the scheduler. That, in turn, changes with the amount of work available and length of workunits. In the past the worst load spikes seemed to appear when we were releasing lots of work. I thought at first it was just the increased load of releasing the work, but I now think it's also the increased work required her hit to search the larger volume of data in the database. So I think the M/T load is small in comparison, but it's good to try to think of everything that might be relevant. ____________ -- Eric Myers "Education is not the filling of a pail, but the lighting of a fire." -- William Butler Yeats | |
ID: 6828 | Rating: 0 | rate:
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Wormholio wrote:
It may also be because the clients try again sooner. When there is no work the average connection frequency is going to be close to 4 hours. When there is plenty of work that rate will drop dramatically, possibly nearly as short as the average task. ____________ BOINC WIKI ![]() ![]() Dirty John Rackham | |
ID: 6835 | Rating: 0 | rate:
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Dirty John wrote: It may also be because the clients try again sooner. When there is no work the average connection frequency is going to be close to 4 hours. When there is plenty of work that rate will drop dramatically, possibly nearly as short as the average task. That seems to be the case. The DB query rate was around 14/sec with no work, and now it's closer to 20/sec. I'm stopping work generation for a while and we'll see how that changes, if it does. ____________ -- Eric Myers "Education is not the filling of a pail, but the lighting of a fire." -- William Butler Yeats | |
ID: 6837 | Rating: 0 | rate:
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Questions and Answers : Pirates@Home Problems : Database was unavailable
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