[bifrost]

Reinventing TCP over UDP is sortof silly, I hope they have a better reason than "they don't want to upstream our changes" lol.

[wmf]

I think the inability to upstream changes into Windows and (ironically) old versions of Android are bigger motivations for using UDP.

[jumpingmice]

Isn't it a pretty good reason? gRPC is terrible in a datacenter context without Google's internal TCP fixes that Linux won't adopt (and which have been advocated for in numerous conference papers since at least 2009). If they are steadfast cavemen what other workaround exists?

[ToFab123]

Apparently Microsoft is considering gRPC as an future replacement for WCF, so that might change. https://news.ycombinator.com/item?id=21055487

[greglindahl]

The standard workaround is to send short messages using UDP and long ones using TCP.

[derefr]

What parts of gRPC are fixed by using it over QUIC vs. TCP (presuming intra-DC traffic and equally long-lived flows)?

[jumpingmice]

Latency caused by packet loss. TCP needs microsecond timestamps and the ability to tune RTOmin down to 1ms before it is suitable for use in a datacenter. With the mainline kernel TCP stack you are looking at, at a minimum, a 20ms penalty whenever a packet is dropped.

[toast0]

TCP over UDP seems rather silly to me, but congestion control and segmentation in userland is pretty useful. Especially so, since Google and partners have made an ecosystem where kernel updates on deployed devices don't happen.