This cannot be enabled by default, as it is a functional change

My understanding is that linux also requires this to be after the bind call, while freebsd requires it to be before the bind call.

Thanks for review 。I have add environment variable SO_REUSEPORT to control this flag。In addition
。In Linux，setsockopt need to be called before bind。Below is the document。

SO_REUSEPORT (since Linux 3.9)
Permits multiple AF_INET or AF_INET6 sockets to be bound
to an identical socket address. This option must be set
on each socket (including the first socket) prior to
calling bind(2) on the socket.

Ah, you are right, I had that backwards (FreeBSD must be afterwards)

Ah, you are right, I had that backwards (FreeBSD must be afterwards)

OS usually check the port in bind call。so i think we should call setsockopt before bind。And i find this document(https://www.freebsd.org/cgi/man.cgi?query=setsockopt&sektion=2&format=html) that also describe this。

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I think it's a good resolution to resolve the issue of nodejs/node#37343

I don't think using an environment variable is the libuv way to do this. I think a better option would be defining a specific uv_tcp_flags flag: UV_TCP_REUSEPORT that can be passed to uv_tcp_bind().

Thanks for review. I have change the code. Looking forward to your review again

I think it's a good resolution to resolve the issue of nodejs/node#37343

I have add this flags into my Node.js branch(branch add-reuseport of https://github.com/theanarkh/node). You can test the performance in Linux 3.9 and above.

Codewise, except some style nits I think it's good, but I've been thinking about it and I'm not sure we should add this option as the SO_REUSEPORT seems to be implemented differently across platforms. (see: https://stackoverflow.com/a/14388707). From what I understand this PR is focused in the Linux implementation which only seems to be implemented also on FreeBSD 12+ by using the SO_REUSEPORT_LB option. So I see two options:

1. Don't add this as you can accomplish the same by calling setsockopt() yourself before calling uv_tcp_bind().
2. Rename the option to UV_TCP_REUSEPORT_LB to be clearer what's the purpose of the flag and have it implemented only where supported (linux 3.9+, FreeBSD 12+).

My choice would be 1 but let's see what other @libuv/collaborators think.

Codewise, except some style nits I think it's good, but I've been thinking about it and I'm not sure we should add this option as the SO_REUSEPORT seems to be implemented differently across platforms. (see: https://stackoverflow.com/a/14388707). From what I understand this PR is focused in the Linux implementation which only seems to be implemented also on FreeBSD 12+ by using the SO_REUSEPORT_LB option. So I see two options:

1. Don't add this as you can accomplish the same by calling setsockopt() yourself before calling uv_tcp_bind().
2. Rename the option to UV_TCP_REUSEPORT_LB to be clearer what's the purpose of the flag and have it implemented only where supported (linux 3.9+, FreeBSD 12+).

My choice would be 1 but let's see what other @libuv/collaborators think.

Thanks for your advice, What I think is that Node.js Server runs under Linux in most cases, so supporting this flag allows Node.js to benefit from Linux. For systems that do not support this flag, I also added compatible code for Node.js(demo code: https://github.com/theanarkh/node/pull/1/files). Do you mean not to support this flag in Libuv, or do not modify the code in uv_tcp_bind? Nginx supports this flag already.

Do you mean not to support this flag in Libuv, or do not modify the code in uv_tcp_bind?

What I mean is that the consumer of libuv (nodejs in this case) could call setsockopt() directly only on specific platforms before calling uv_tcp_bind()

Do you mean not to support this flag in Libuv, or do not modify the code in uv_tcp_bind?

What I mean is that the consumer of libuv (nodejs in this case) could call setsockopt() directly only on specific platforms before calling uv_tcp_bind()

before uv_tcp_bind the socket have not been made(make in uv__tcp_bind). consumer make the socket？

Yeah, I forgot to add, use uv_tcp_init_ex() instead of uv_tcp_init() to create the socket

Yeah, I forgot to add, use uv_tcp_init_ex() instead of uv_tcp_init() to create the socket

I think it should be that the bottom layer supports certain features, and then the upper layer decides whether to enable it, rather than when the upper layer needs to use the feature, it needs to write similar repetitive code, which will increase the burden on the upper layer.

I understand, but the issue here is that it's not a feature that can be implemented cross-platform. BTW, as a reference here's an issue from some years ago about this very same topic: #1229 (comment). The solution it refers to is also using uv_tcp_init_ex().

I understand, but the issue here is that it's not a feature that can be implemented cross-platform. BTW, as a reference here's an issue from some years ago about this very same topic: #1229 (comment). The solution it refers to is also using uv_tcp_init_ex().

Thanks again, i get it, i try to support this in C++ and js of Node.js。

This issue has been automatically marked as stale because it has not had recent activity. It will be closed if no further activity occurs. Thank you for your contributions.

I'm going to close this. Please feel free to re-open in case you thing there's more to discuss. Thanks

I have read the source code of libuv, and found that the function of uv__set_reuse was called in uv__udp_bind. Does this make harmful for cross-platform envrionment?

@yunnysunny I'm not sure I understand your question. Can you elaborate?

@yunnysunny I'm not sure I understand your question. Can you elaborate?

@santigimeno said we should use uv_tcp_init_ex to set the option of SO_REUSEPORT instead of setting it in the function of uv__tcp_bind directly. But when use the option of SO_REUSEPORT, it sets it just in uv__udp_bind. I think we should use the same design to resolve the similar problems in our code.

SO_REUSEPORT is different between tcp and udp. For udp it means mutilcast which is supported in multiple platform. So i think this is why the Libuv supports it.

SO_REUSEPORT is different between tcp and udp. For udp it means mutilcast which is supported in multiple platform. So i think this is why the Libuv supports it.

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