Tile locking performance issue

[Dimitar Misev]

Locking seems to have a large overhead, to reproduce

#!/bin/bash

rasql -q 'create collection test GreySet'
# this will insert an object of 2601 tiles
rasql -q 'insert into test values marray i in [0:100,0:100] values 1c tiling aligned [0:1,0:1] tile size 4'
time rasql -q 'select sdom(c) from test as c' --out string 

[Dimitar Misev]

I submitted a patch that drastically reduces the performance overhead, however there is still significant overhead, I assume related to ecpg connections to postgres.

I haven't looked at it, are they established and terminated for every tile or something similar?

[Kinga Lipskoch]

The connection is established once at the creation of the lockmanager instance and closed once at the end of it's work.

[Kinga Lipskoch]

I will take a look and give some feedback as soon as I can.

[Dimitar Misev]

I submitted another patch that moves the prepared statements into the connect() method. This further improved the performance, so the above query sdom() query takes 1.6s now.

[Dimitar Misev]

Lowering priority as performance has been substantially improved.

[Kinga Lipskoch]

A patch simplifying the queries and the table structure was submitted and applied.
I will do further measurements to evaluate the current performance.

[Kinga Lipskoch]

Above are the measurements I made before and after the performance improvements.

Now, on my university computer, the select needs below 1 second to execute.

[Peter Baumann]

thanks for providing the results. 2 things I notice:

• select gets slower by a factor of 40 in the optimized lockmgr; we definitely need to work on this.
• insert: the "optimized lockmgr" version is the slowest, slower than unoptimized?

[Dimitar Misev]

Will you submit the patch soon Kinga?

[Kinga Lipskoch]

Yes, I will submit the patch soon. I wanted to finish my repeated measurements and
add some code documentation and will be able to submit the corresponding patch.

[Kinga Lipskoch]

Patch submitted.

[Kinga Lipskoch]

The patch was applied, so after a point you can close the ticket.

[Dimitar Misev]

changeset:a4535fe0f14e2c4b252acb06db16bc2251fa0462