Bug #5925: Performance: dynamic function lookup runs very slowly under Saxon-JS - SaxonJS - Saxonica Developer Community

Actions

Send by e-mail Copy link

Bug #5925

closed

Performance: dynamic function lookup runs very slowly under Saxon-JS

Added by Mary Holstege almost 2 years ago. Updated about 1 year ago.

Status:

Closed

Priority:

Low

Assignee:

Category:

Sprint/Milestone:

Start date:

2023-03-17

Due date:

% Done:

100%

Estimated time:

Applies to JS Branch:

2, Trunk

Fix Committed on JS Branch:

2, Trunk

Fixed in JS Release:

SaxonJS 2.6

SEF Generated with:

Platforms:

Company:

Contact person:

Additional contact persons:

Description

This is a strange performance issue.

I have tried to boil this down, but when I do so, the performance problem evaporates so I'm afraid there is a huge wodge of code here, for which I apologize.

When I run this stylesheet in XSLT, it runs in a few seconds. This is a direct translation of some XQuery code, which also runs in seconds. In node (or a browser), however it takes over a minute. If I run the full set of tests it takes 11 hours to run instead of half a minute.

I ran some basic profiling: it seems to be killing itself with GC if I'm reading this right. (see profile20230317.txt)

The script go.sh is how I'm running this; obviously all the paths and whatnot would need fixing. It is Saxon 12.0 to do the export to JSON and then xslt3.js to run it.

Saxon-JS 2.5, Saxon 12.0

Files

Download all files

20230317.zip (251 KB) 20230317.zip	Zip file of code	Mary Holstege, 2023-03-17 17:56
profile20230317.txt (16.8 KB) profile20230317.txt	Profile	Mary Holstege, 2023-03-17 18:01

Actions

Copy link

Updated by Norm Tovey-Walsh almost 2 years ago

Thanks, Mary. I'll try to look at this next week.

Actions

Copy link

Updated by Michael Kay almost 2 years ago

John Lumley points out that the example makes extensive use of packages. We may need to take a look at the SaxonJS code for binding cross-package component references (such as function calls), which has probably not been stress-tested.

Actions

Copy link

Updated by Norm Tovey-Walsh over 1 year ago

Status changed from New to Resolved
Applies to JS Branch Trunk added
Fix Committed on JS Branch Trunk added

A quick review of the profile pointed me to the code for dynamic function lookup. The test case does more than 600 lookups but only actually calls 5 functions. So we were doing ~595 unnecessary lookups. That's a linear search (I think) through all of the possible functions. Rather than trying to make a more complex data structure, I simply added a cache. The test case is now 13x faster and finishes easily in a couple of seconds.

The patch didn't apply cleanly to the saxonjs2 branch so I haven't ported it. If we end up doing another Saxon2 release, we should.

Actions

Copy link