[Question] Using grpc compression weirdly leads to low throughput

[dentiny]

I have a service using grpc to stream data to client-side.
For the original implementation, the average throughput could be ~110MBps with a 1Gbps NIC, so I think bandwidth itself is a bottleneck. The usual way is to enable compression/decompression.

I found grpc supports compression natively. The only line of code I added at server side is

builder.SetDefaultCompressionLevel(GRPC_COMPRESS_LEVEL_LOW);

with no change at client-side. But the throughput drops stably.

With dstat -n, the throughput looks like

  33M  121k
2948B 1756B
 306B  166B
3026B  688B

which looks like the average throughput is 7MBps.
And with response.ByteSize(), I calculated the throughput is ~11MBps, still way below the one before compression.

The observation doesn't change as the compression level, whether it's low, medium or high.

I want to know, if I'm using the compression in grpc wrongly?

[Mark D. Roth]

I answered this on the grpc.io mailing list.