Overhead of JSON validation is quite noticeable especially for large documents

Build 5.5.0-1960.

Environment:

• 1 node
• 1 ephemeral bucket
• passive compression mode

Here is my write-only workload (50K updates/sec):

./cbc-pillowfight --batch-size 100 --num-items 5000000 --num-threads 25 --min-size $size --max-size $size --set-pct 100 --num-cycles 40000 --no-population --compress --json --rate-limit 50000  --spec couchbase://172.23.133.13/bucket-1?password=password

I iterate using different document sizes (from 256B to 8KB). In the meantime, I measure overall CPU utilization ("Solaris mode") and CPU overhead of two expensive calls:

• JSON_checker::Validator::validate
• snappy::RawUncompress

Overhead of those functions is measured using Linux perf. I picked mc:worker_0 for profiling.

Of course, my micro-benchmark doesn't represent typical production workloads. I am rather trying to examine a very specific code path. In regular tests the overhead is usually less than 10%.

Reported results are still very concerning in my opinion. Passive compression mode made things a little bit worse since we need to inflate JSON documents before validation.