Hugh performance issues on heavy Tags usage

[andrerom]

It's been observed by several (partners, eZ folks) that Tags bundle does not perform at all due to excessive cache lookups, the issue is most visible on v2 as in-memory cache on v1 tends to hide it. From profiling @bdunogier could see 4 duplicate lookups for tags due to fromHash() being implicitly called several times, and this seems to correspond to what @dspe observed during an audit too.

From initial look it seems two things could be done in fromHash:

• change to multi lookup of tags to avoid the foreach loading approach
• local caching of values (for instance property with cached value, checksum of ids looked for, and timestamp to not cache too long on cli operations)

Or the lookup should rather be done in external storage or something.

Local cache might not be needed once we ship SPI cache with in-memory cache in 2.5, but TagsHandler will need to be adapted for it will most likely be per handler logic.

[emodric]

Thanks for the report @andrerom 👍

If you have specific suggestions on how to improve ( a PR ;) ), I'll gladly merge them!

[andrerom]

Not really as it seems to go deep, but I might be wrong, @bdunogier was the one spotting this so he might know.

[emodric]

@andrerom Will this be closed by #97 ?

[andrerom]

Mostly, so yes you can close this once it's merged.

Remaining issues:

• doing this in fromHash (but no clear alternative for now)
• why kernel called fromHash several times (4) in the profilings done, as opposed to just once

[emodric]

Mostly, so yes you can close this once it's merged.

:+1:

why kernel called fromHash several times (4) in the profilings done, as opposed to just once

I'll try to investigate.

[emodric]

Mostly fixed by #97