TTree Scan function on windows platform, using vscode to connect wsl connection jupyter reported a deadlock.

[Esword618]

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Description

On windows, when vscode is used to connect pyroot's jupyter of wsl subsystem, pyroot's TTree Sacn function is stuck. Other jupyter lab in wsl do not have this situation. Why is this, is there any solution? Note that vscode is used to connect to jupyter lab in wsl.

Reproducer

from ctypes import c_double, c_int
from ROOT import TFile, TTree,TCanvas
guan = TFile("guan.root", "recreate")

ming = TTree("ming", "This is my first tree")
i = c_int(1)
a = c_double(2.2)
b = c_double(0.0)

ming.Branch("i", i, "i/I")
ming.Branch("a", a, "a/D")
ming.Branch("b", a, "b/D")

for j in range(100):
    i = j
    a = i * 0.1
    b = a * a * 9
    ming.Fill()

ming.Write()
# BUG
ming.Scan()

ROOT version

root_v6.30.01.Linux-ubuntu22-x86_64-gcc11.4

Installation method

build

Operating system

wls and ubuntu22.04

Additional context

No response

[guitargeek]

Hi! What happens when you do Write() at the end, and not before Scan()? Usually the write should happen only after interacting with the object, so maybe that's worth to try out. Otherwise I have no idea.

[Esword618]

The "write" function is normal, and the "scan" function is abnormal.

[guitargeek]

Yes I understand that, but is the Scan() still abnormal if you don't do the Write() before?

[Esword618]

The same is true when I read a root file, which is independent of the "Write" function.

[guitargeek]

Ok, then I think we can't help you without a reproducer. The only Windows user I know in the ROOT team is @bellenot, so I assigned the PR to him.

[bellenot]

On windows, when vscode is used to connect pyroot's jupyter of wsl subsystem

Can you describe exactly how you connect from VS Code to PyRoot's Jupyter in WSL?

[bellenot]

OK, I managed to set-up an environment. Here is what I get with your example and root_v6.30.02.Linux-ubuntu22-x86_64-gcc11.4:

Welcome to JupyROOT 6.30/02
************************************************
*    Row   *       i.i *       a.a *       b.b *
************************************************
*        0 *         1 *       2.2 *       2.2 *
*        1 *         1 *       2.2 *       2.2 *
*        2 *         1 *       2.2 *       2.2 *
*        3 *         1 *       2.2 *       2.2 *
*        4 *         1 *       2.2 *       2.2 *
*        5 *         1 *       2.2 *       2.2 *
*        6 *         1 *       2.2 *       2.2 *
*        7 *         1 *       2.2 *       2.2 *
*        8 *         1 *       2.2 *       2.2 *
*        9 *         1 *       2.2 *       2.2 *
*       10 *         1 *       2.2 *       2.2 *
*       11 *         1 *       2.2 *       2.2 *
*       12 *         1 *       2.2 *       2.2 *
*       13 *         1 *       2.2 *       2.2 *
*       14 *         1 *       2.2 *       2.2 *
*       15 *         1 *       2.2 *       2.2 *
*       16 *         1 *       2.2 *       2.2 *
*       17 *         1 *       2.2 *       2.2 *
*       18 *         1 *       2.2 *       2.2 *
*       19 *         1 *       2.2 *       2.2 *
*       20 *         1 *       2.2 *       2.2 *
...
*       33 *         1 *       2.2 *       2.2 *
*       34 *         1 *       2.2 *       2.2 *
*       35 *         1 *       2.2 *       2.2 *
*       36 *         1 *       2.2 *       2.2 *
*       37 *         1 *       2.2 *    
Output is truncated. View as a scrollable element or open in a text editor. Adjust cell output settings...
Type <CR> to continue or q to quit ==> Type <CR> to continue or q to quit ==> Type <CR> to continue or q to quit ==> Type <CR> to continue or q to quit ==>

And then, if I type again ming.Scan() in a new cell I got the same output...

[Esword618]

My data volume is relatively large, and the one-time output of the Scan function is limited. I guess this is the reason. This uses jupyter lab for code editing in the browser, and using the Scan function is not a problem. Mainly in vscode, I use vscode to connect to the local wsl subsystem and use vscode's jupyter editor. Will this know the reason for the jupyter in vscode itself?

[bellenot]

Mainly in vscode, I use vscode to connect to the local wsl subsystem and use vscode's jupyter editor.

Same here.

Will this know the reason for the jupyter in vscode itself?

What do you mean? I tried your example and it works just fine...

[pcanal]

Type to continue or q to quit ==>

This is the potential source of the problem (i.e. Scan waiting for user input). To disable this feature use:

tree->SetScanField(0);

[Esword618]

okk,thanks.

[bellenot]

OK, then I close this issue

[github-actions[bot]]

Hi @bellenot,

It appears this issue is closed, but wasn't yet added to a project. Please add upcoming versions that will include the fix, or 'not applicable' otherwise.

Sincerely, :robot: