[Bug] macOS 下持续输出大量 SSH 日志时会话被断开并显示 code 0

[omingkai]

Operating system

macOS 26.6.1 (Apple Silicon / arm64)

Netcatty version

1.1.81

How did you install Netcatty?

GitHub Release (.dmg / .exe / .AppImage / .deb / .rpm / .pacman)

Affected area

SSH connection / terminal

Can you reproduce it?

Always (100%) when the remote log output is sufficiently high-volume.

Steps to reproduce

1. Open Netcatty on macOS and connect to a Linux/OpenSSH server through SSH.

2. Run a continuous tail against a busy application log:

   tail -n 200 -F /path/to/high-throughput.log

3. Wait until the log starts producing many lines in a very short interval (multiple lines can arrive within the same millisecond).

4. Netcatty disconnects the SSH session and shows the disconnect overlay.

5. The terminal ends with:

   [session closed (code 0)]
   

6. Reconnect and reduce terminal output using a filter:

   tail -n 200 -F /path/to/high-throughput.log \
     | grep --line-buffered -Ei 'ERROR|Exception|Caused by:'

   Reducing the amount of rendered output mitigates the problem.

Expected behavior

High-volume terminal output should be handled with bounded buffering/backpressure or reduced rendering frequency. The terminal may skip intermediate visual frames if necessary, but the active SSH connection should remain established.

Actual behavior

During sustained high-volume text output, the entire SSH session is disconnected. Netcatty displays Disconnected, requires a reconnect, and prints [session closed (code 0)].

This does not look like an idle timeout because the connection is actively receiving data when it closes. Filtering the stream to reduce the number of rendered lines mitigates the disconnect.

Logs / screenshots

The visible terminal state at failure is:

Disconnected
[session closed (code 0)]

The original screenshot contains private host information, so it is intentionally not attached.

Possibly related, but with different trigger conditions:

• Web SSH 终端频繁从客户端侧主动断开，导致 session 丢失且无法重连恢复 #1181 reports general client-initiated Web SSH disconnects.
• [Bug] 版本1.1.78连接Openwrt系统时退出（报代码0） #2935 reported code 0 on OpenWrt with v1.1.78; this report reproduces on macOS desktop v1.1.81 with a Linux/OpenSSH target specifically under sustained high-volume log output.

Before submitting

• I searched existing issues and did not find an issue with the same high-volume-output trigger.
• I removed passwords, private keys, host addresses, usernames, and other secrets from this report.

[netcatty-bot]

感谢反馈。这是 macOS 上 SSH 终端在持续大量输出时把会话直接断开的问题，我们会按这个方向处理。

刷日志时连接应当一直保持。画面可以少画几帧，但不该整段掉线，然后出现断开和 session closed code 0。减少输出行数后现象减轻，也说明问题出在客户端消化流量这一侧，而不像空闲超时。

终端里其实已经有输出节流，本来就是为这种持续刷屏准备的。但在高峰时仍可能把会话收成已断开。维护者会从终端输出和 SSH 连接这条链路接手跟进。

如果再次出现，方便的话把断线前几秒的应用日志一并附上，会更快判断是画面跟不上还是底层连接被关掉。

[binaricat]

现有信息还无法定位，最好能把ssh日志贴出来。我这里还没办法复现。

[omingkai]

现有信息还无法定位，最好能把ssh日志贴出来。我这里还没办法复现。

我又尝试了下 暂时也没复现出来了 但是之前出现了两次。

[binaricat]

现有信息还无法定位，最好能把ssh日志贴出来。我这里还没办法复现。

我又尝试了下 暂时也没复现出来了 但是之前出现了两次。

没事 那这个issue先开着观察一下吧，后续如果再能复现贴日志给我。我自己没法复现，同macos。