gabotechs commented on code in PR #12083:
URL: https://github.com/apache/arrow-rs/pull/12083#discussion_r4482262320
##########
arrow-ipc/benches/ipc_writer.rs:
##########
@@ -81,6 +81,34 @@ fn criterion_benchmark(c: &mut Criterion) {
})
});
+ for (rows, threads) in [(8192, 1), (65536, 1), (8192, 16), (65536, 16)] {
+ group.bench_function(
+
format!("StreamEncoder/encode_10/lz4/rows={rows}/threads={threads}"),
+ |b| {
+ let batch = create_batch(rows, true);
+ b.iter(|| {
+ std::thread::scope(|s| {
+ for _ in 0..threads {
+ s.spawn(|| {
+ let options = IpcWriteOptions::default()
+
.try_with_compression(Some(CompressionType::LZ4_FRAME))
+ .unwrap();
+ let mut encoder =
StreamEncoder::try_new_with_options(
+ batch.schema().as_ref(),
+ options,
+ )
+ .unwrap();
+ for _ in 0..10 {
+ black_box(encoder.encode(&batch).unwrap());
Review Comment:
Single thread just measures raw compression speed. The threads=16 cases are
there to catch contention that only shows up when multiple encoders run at
once, e.g. allocator pressure from each one setting up its own buffers. Without
concurrent cases, that kind of regression (or improvement) would be invisible
in these benchmarks.
My guess for there to be contention is that different threads will start
competing for big allocations through a single global allocator doing syscalls,
but it's just a guess, the main reason for me to include the multithreaded
cases is because I have empirically tested that the biggest performance
improvements happen there.
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