Read multiple sockets from single thread [low-latency]

Question

As a network client I would like to follow the input from two TCP connections. Both servers send a few packets per second. Each packet is small in size when compared to the available bandwidth.

Ideally we'd like to read both sockets from a single thread for the best latency. My initial plan was to use FIONREAD from ioctl(2) on each connection in a loop, and only read when data is available. Are there other options? CPU consumption is less relevant than low latency.

@ikegami You do actually. This is a common misconception. It appears as though you don't, but in practice numerous subtle errors are possible if you use select() with blocking-mode sockets. — user207421
– user207421, Commented Mar 18, 2024 at 4:14
@ikegami accept() can return null. read() and write() can return -1/EAGAIN/EWOULDBLOCK. How many do you need? — user207421
– user207421, Commented Mar 18, 2024 at 7:03
@user207421 Re "accept() can return null.", So? /// Re "read() and write() can return -1/EAGAIN/EWOULDBLOCK.", well yeah, which is why you use select to let you know when it wouldn't return that. — ikegami
– ikegami, Commented Mar 18, 2024 at 13:09

score 1 · Accepted Answer · 2024-03-18 07:19:25Z

1

You want to use one of these I/O multiplexing primitives:

Non-blocking sockets which would give you similar behavior as your ioctl(2). Usually, it's combined with one of the options below to avoid a busy loop.
select(); "On Linux [...] it may be safer to use O_NONBLOCK on sockets that should not block"
poll()
epoll() (Linux)
POSIX aio_ family of functions. Not sure it's used much and Linux the library spawns threads.
uring (Linux)

Collectives™ on Stack Overflow

Read multiple sockets from single thread [low-latency]

1 Answer 1

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

Comments

Your Answer

Sign up or log in

Post as a guest

Related