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Re: PBXT "hangs" sometimes but regularly

 

Hi Erkan,

Yes. Strange pause. But I cannot see what the engine is doing in that time.

There must be activity in some missing statistics, for example, record, row or index file writing.

Unfortunately, when displaying all statistics, the output is very wide. What xtstat needs is a feature which logs all statistics but just displays what you select.

Then, if you see a problem that does not show up in the displayed statistics you can still go back and check the others at the time.

On Nov 30, 2010, at 3:05 AM, erkan yanar wrote:

Moin Paul

On Mon, Nov 29, 2010 at 10:23:38AM +0100, Paul McCullagh wrote:


The problem here is the index cache is full, and the thread which is
flushing the index is hanging in sync (i.e. flush to disk). The rest
of the system is hanging because it needs a clean page in the index.

I did quite a bit of work to improve this in 1.1 and 1.5.

But in general, if the index cache is really large, it need to be
flushed more regularly to ensure that too many changes do not
accumulate. Checkpointing should do this, but there is a bug in 1.0.

You checkpoint frequency is 128M, xtstat says to-chkpt = 1049M. This
means the checkpoint has not occurred as often as he should.

This problem should be fixed in 1.1.


While 1.5.02 Beta handles IO a lot better than 1.0.11-7, you may be
interested in that checkpointing issue:
pbxt_checkpoint_frequency    = 67108864

time time xact xact xact xact stat stat ilog ilog ilog ilog ilog xlog xlog xlog xlog xlog xlog xlog xlog to to to sweep row row row row curr msec commt rollb waits dirty read write in out rd.ms wr.ms syncs/ms in out rd.ms wr.ms syncs sy.ms hits miss chkpt write sweep waits sel ins upd del 101130 03:45:13 5001 198t 0 0 10.9t 0 198t 320M 0 83 0 0/0 0 21.1M 0 12 9 3576 69.6t 0 813M 9833K 0 13 0 198t 0 0 101130 03:45:18 5001 9501 0 0 5148 0 9501 0 0 0 0 0/0 0 0 0 0 0 5001 0 0 813M 9833K 0 1 0 9501 0 0 101130 03:45:23 5001 0 0 0 5148 0 0 0 0 0 0 0/0 0 0 0 0 0 5001 0 0 813M 9833K 0 0 0 0 0 0 101130 03:45:28 5001 80.1t 0 0 13.8t 0 80.1t 0 0 0 0 0/0 0 8192K 0 4 1 4993 1 0 814M 17.6M 115M 5 0 80.1t 0 0 101130 03:45:33 5001 179t 0 0 10.3t 0 179t 0 0 0 0 0/0 1244K 19.7M 0 8 20 4395 119t 39 837M 6772K 0 13 0 179t 0 0 101130 03:45:38 5001 12.7t 0 0 9084 0 12.7t 0 0 0 0 0/0 0 0 0 0 0 5001 5507 0 837M 3756K 0 1 0 12.7t 0 0 101130 03:45:43 5001 78.4t 0 0 8907 0 78.4t 0 0 0 0 0/0 0 8192K 0 3 1 4994 18.1t 0 840M 8192K 0 5 0 78.4t 0 0 101130 03:45:48 5001 156t 0 0 4410 0 156t 0 0 0 0 0/0 0 16.0M 0 8 2 4985 67.5t 0 856M 8192K 0 11 0 156t 0 0 101130 03:45:53 5001 78.9t 0 0 7213 0 78.9t 0 0 0 0 0/0 0 8192K 0 6 1 4991 1 0 864M 16.0M 0 7 0 78.9t 0 0


Best Regards
Erkan

--
über den grenzen muß die freiheit wohl wolkenlos sein




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