[WSL2] Using head with some binaries hangs the terminal

[onomatopellan]

• Your Windows build number: (Type ver at a Windows Command Prompt)
  Version 10.0.18980.1
  Ubuntu 18.04 WSL2 from the Store.

• What you're doing and what's happening:
  head $(which gzip)

• What's wrong / what should be happening instead:
  In WSL1 it shows some characters and ends with the message "head: error writing 'standard output': Input/output error"
  In WSL2 the Ubuntu terminal/Windows Terminal hangs after showing some characters and not even CTRL+C works. Only option is closing the tab/window.
  Head works correctly in VScode's terminal with Remote WSL plugin or using xterm with VcXsrv though.

[Biswa96]

I can reproduce your issue. I think the bug is in the wsl.exe read/write thread pools. There is no error in strace output and LxssManager event logging. I also tried it with my puppy without any issue. Here is the output of wsl.exe event logs:

[Microsoft.Windows.Subsystem.Lxss] LxssException File:onecore\vm\wsl\lxss\lxcmdlineshared\relay.cpp FunctionName: Line number:232 Type:0 HRESULT:0x80074005 Message: Code:
[Microsoft.Windows.Subsystem.Lxss] LxssVerboseLog File:onecore\vm\wsl\lxss\lxcmdlineshared\relay.cpp FunctionName: Line number:447 Type:2 HRESULT:0x80074005 Message:onecore\vm\wsl\lxss\lxcmdlineshared\relay.cpp(232)\wsl.exe!00007FF665C7946D: (caller: 00007FF665C7919C) Exception(1) tid(594) 80074005  Code:

[onomatopellan]

Thanks for confirm it. I wasn't sure if it was more a terminal/conPTY issue but I see is Lxss related.

[Biswa96]

WSL1 and WSL2 do not use ConPTY for normal Linux processes. It is used only during execution of Win32 process.

[onomatopellan]

@benhillis Can you reproduce this bug? Since gzip binary can be updated in any moment a better repro step would be:

for i in /bin/*; do head ${i}; done

With this there is always a binary that hangs the terminal.

Edit: VSCode problem was not related.

VSCode default terminal has this issue too, it's the VSCode terminal when using "VSCode Remote WSL plugin" that can handle head without a hang.

[benhillis]

@onomatopellan - Sorry didn't see this thread. I am not seeing a hang, but I am seeing us exit out of the shell when I run some binaries. I'll look into this today.

[benhillis]

Tracking this here: microsoft/terminal#3320

[onomatopellan]

Great, thanks!

[onomatopellan]

I just tested latest Windows Terminal on build 19033 and indeed problem it's already fixed. Thanks again!