xwin-xdg-menu high cpu usage with rxvt-unicode

[Viet-Duc Le]

I've tested the patched version.
At the moment, xwin-xdg-menu no longer incurs high resources with multiple instances of rxvt-unicode.

@Takashi: Thanks for investigating the issues and providing a patch.
@Jon: Thanks for providing the test package.

‐‐‐‐‐‐‐ Original Message ‐‐‐‐‐‐‐

On Thursday, June 24th, 2021 at 1:41 AM, Jon Turney <jon.turney@dronecode.org.uk> wrote:

> On 23/06/2021 04:08, Takashi Yano wrote:
>
> > On Mon, 21 Jun 2021 05:49:28 +0000
> >
> > Viet-Duc Le wrote:
> >
> > > Hi,
> > >
> > > I've encountered a peculiar issue with rxvt-unicode launched from xwin-xdg-menu (20170321-1)
> > >
> > > The image below corresponds to two rxvt-unicode instances, each occupies 30% of system resouce.
> > >
> > > https://imgur.com/a/FTFwIrZ
> > >
> > > I'm using the the latest version of cygwin. 'cygcheck.out' is attached per guideline.
> > >
> > > Steps to reproduce:
> > >
> > > -   Start XWin Server from Start menu
> > > -   X applications menu -> System Tools -> rxvt-unicode
> > > -   Kill rxvt-unicode to free the resource again
> > >
> > > Other observations:
> > >
> > > -   XTerm does not incur high resources.
> > > -   Manually launching rxvt-unicode from XTerm does not incur high resources.
> > >
> > > I think this is not an issue with rxvt but with xwin-xdg-menu.
> > >
> > > On laptop, it is very noticeable when the fan kicks in.
> > >
> > > Insights and suggestions are much appreciated.
> > >
> > > Thanks.
> > >
> > > Viet-Duc
> >
> > I looked into this problem and found the cause.
> >
> > urxvt seems to close stdout while xwin-xdg-menu use select()
> >
> > to read stdout of the launched apps. Since stdout is closed,
> >
> > select() returns repeatedly without any output. This causes
> >
> > high cpu load.
> >
> > I also confirmed that the following patch for xwin-xdg-menu
> >
> > resolves the issue.
>
> [...]
>
> > Jon, could you please have a look?
>
> Thanks very much for looking into this, and the patch.
>
> That looks right.
>
> I applied the patch, and built and uploaded a xwin-xdg-menu-20210623-1
>
> test package.
>
> Perhaps you could try that, and see if it improves things for you?
>
> (Similar code is used in XWin, so I also need to make a similar change
>
> there)
>
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