[Bug] CoreCLR / .NET 10: API.EmitServerLatent Causes Infinite NetThread Send Queue Flood & Deadlock on Consecutive Calls

[MosIbOad]

Summary

When using API.EmitServerLatent from a C# (.NET 10 / CoreCLR) client resource to transfer a payload exceeding ~1 MB (e.g., 1.5 MB), the initial transfer completes successfully. However, consecutive calls to EmitServerLatent cause an unrecoverable deadlock in NetThread, resulting in continuous Client::NetThread: Many packets in the send queue spam in the console. The payload never reaches the server, and outgoing latent traffic becomes permanently blocked until client reconnection.

Issue type

Client

Repro rate

Always

Server build version

FXServer-early-access b170 win32

OS

No response

CPU

No response

GPU

No response

RAM

No response

Storage type

None

Connection type

None

ISP and bandwidth

No response

DxDiag

No response

Network graph

No response

Platform

None

OS version / distribution

No response

CPU

No response

RAM

No response

Using txAdmin?

None

Hosting provider

None

Machine type

None

/perf endpoint output

No response

DDoS protection

No response

ulimit -n value (Linux only)

No response

Docker Compose file (Docker only)

No response

Steps to Reproduce

1. Define a minimal client-side command using API.EmitServerLatent:

[OnCommand("sendbigdataserver")]
public void SendBigDataTest()
{
    int sizeInBytes = 1024 * 1024 + (512 * 1024); // ~1.5 MB
    const string chars = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789";

    string bigData = string.Create(sizeInBytes, chars, (span, charSet) =>
    {
        var random = new Random(1337);
        for (int i = 0; i < span.Length; i++)
        {
            span[i] = charSet[random.Next(charSet.Length)];
        }
    });

    API.EmitServerLatent(-1, "server:sendBigData", bigData);
}

2. Register the corresponding server-side event listener:

[OnNetEvent("server:sendBigData")]
public void ServerBigDataTest([FromSource] Player player, string bigData)
{
    API.Log.Info($"[Server] bigData received successfully! Length: {bigData.Length}");
}

3. Open the F8 client console and execute: sendbigdataserver
   • The data arrives at the server, though Client::NetThread: Many packets in the send queue warnings appear temporarily during transfer.
   • Once the initial large payload finishes transmitting, execute the sendbigdataserver command in the console a second time.

Expected Behavior

The second latent event transmission should initialize normally, send all packets through the latent channel, and arrive at the server without packet drop.

Once an EmitServerLatent transmission completes, the client-side NetThread queue and latent channel state machine should flush and reset, allowing subsequent transfers without flooding the send buffer.

Actual Behavior

The second payload never reaches the server.
The client console enters an unrecoverable infinite loop, flooding the log continuously with:

Client::NetThread: Many packets in the send queue: 287
Client::NetThread: Many packets in the send queue: 512
Client::NetThread: Many packets in the send queue: 512
Client::NetThread: Many packets in the send queue: 287
Client::NetThread: Many packets in the send queue: 512

Evidence

https://www.youtube.com/watch?v=KbwGhbgowh4

Additional Context

No response

[wolfram-cfx]

Hi, thanks for the report. We will provide a improvement for large payloads in the next patch.

[Gogsi]

Hello,
A fix for this issue has been implemented in November 11 patch for FiveM for GTAV Enhanced. Please try again and let us know if the issue persists. Thanks for your help!