[ecbadeaux]

Add a writer performance test

Adds performance_tests/writer_performance_test/, a second performance test that measures recording through the writers across socket writers (UDP, Unix), buffer sizes, thread counts, loads and ways of using a counter. The existing performance_test is unchanged.

How it works

• The test opens its own local socket in place of spectatord and counts what arrives.
• Each configuration records in a separate process through the public API (Registry, Config, WriterConfig, Counter), then exits normally so the library flushes.
• Each configuration is measured three times; the report shows the median and the spread.

What it reports

• Lines recorded per second, per thread, and speed-up over one thread
• Time per call: median, 99th percentile, longest
• Processor time per line
• Share of recorded lines that arrived, and lines per datagram
• Under a paced load, the delay from recording a line to its arrival
• Optional CSV output and comparison against an earlier run (--baseline)

Running it

source venv/bin/activate
BUILD_DIR=cmake-build-release BUILD_TYPE=Release ./build.sh skiptest
./cmake-build-release/performance_tests/writer_performance_test/writer_performance_test --full
The default run takes about 2 minutes, --full about 12 minutes, and --smoke a few seconds. See the README in the folder for options and how to read the report.