[R-SIG-Mac] tcltk causes help() to hang in R 4.2.0 on macOS

[John Fox]

On 2022-06-08 12:36 p.m., John Fox wrote:
> Dear Thomas,
> 
> Thanks for this additional information.
> 
> I added some of my own defensive code to the development version of the 
> Rcmdr package, to set the "help_type" option to "text" for macOS. I'll 

I should have added that help_type is set to "text" for R version 4.2.0 
only!

> modify that to all non-Windows platforms, and also include this in the 
> CRAN version of the package.
> 
> I currently test on macOS and Windows systems but when I have a chance 
> will get a Linux system working as well.
> 
> Best,
>   John
> 
> On 2022-06-08 12:16 p.m., Tomas Kalibera wrote:
>> For reference, this problem is not macOS specific, it also exists on 
>> Linux (but not on Windows which use a different code path) and the 
>> core problem is how to prevent re-entrant execution of R event 
>> handlers when run from the R/tcltk event loop, itself running from an 
>> R event handler.
>>
>> R-patched now contains a defensive work-around from Simon.
>>
>> We have added a more efficient and cleaner fix to R-devel, but there 
>> is some risk of breakage: this form is "the documented way" but didn't 
>> work on some systems ~22 years ago. So it would be great if people 
>> using Tcl/Tk in R on Unix, and particularly those with rarely used 
>> window managers, could test their applications or the tcltk package 
>> demos and report any issues well before the next release.
>>
>> Thanks
>> Tomas
>>
>> On 5/30/22 01:27, John Fox wrote:
>>> Dear Simon,
>>>
>>> Thank you for addressing this problem so promptly.
>>>
>>> Best,
>>>  John
>>>
>>> On 2022-05-29 6:51 p.m., Simon Urbanek wrote:
>>>> Actually, I take back the reference to the commit - the deadlock is 
>>>> true, and removing the line is a work-around, but r78421 was not 
>>>> necessarily the regression. The issue seems to be caused by a 
>>>> combination of Tcl/Tk and KaTeX (the latter causes the browser to 
>>>> issue multiple parallel http-requests and the former causes the 
>>>> deadlock in its event loop) which has not been there in earlier R 
>>>> versions.
>>>>
>>>> Cheers,
>>>> Simon
>>>>
>>>>
>>>>> On 30/05/2022, at 10:09 AM, Simon Urbanek 
>>>>> <simon.urbanek using r-project.org> wrote:
>>>>>
>>>>> John,
>>>>>
>>>>> thanks, this is a regression caused by r78421 (deadlock when 
>>>>> TclTk's event loop is called in http processing). Removing L875 in 
>>>>> src/modules/internet/Rhttpd.c restores the previous behavior, but 
>>>>> the underlying problem is more complex and will require more 
>>>>> investigation.
>>>>>
>>>>> Cheers,
>>>>> Simon
>>>>>
>>>>>
>>>>>> On 29/05/2022, at 5:36 AM, John Fox <jfox using mcmaster.ca> wrote:
>>>>>>
>>>>>> Dear R-sig-mac list members,
>>>>>>
>>>>>> I've discovered that loading the tcltk package apparently causes R 
>>>>>> 4.2.0 (including the current patched version) to hang on an M1 Mac.
>>>>>>
>>>>>> Try, e.g.,
>>>>>>
>>>>>> library("tcltk")
>>>>>> help("lm")
>>>>>>
>>>>>> My session info:
>>>>>>
>>>>>> ------- snip -------
>>>>>>
>>>>>>> sessionInfo()
>>>>>> R version 4.2.0 Patched (2022-05-28 r82413)
>>>>>> Platform: aarch64-apple-darwin20 (64-bit)
>>>>>> Running under: macOS Monterey 12.3.1
>>>>>>
>>>>>> Matrix products: default
>>>>>> BLAS: 
>>>>>> /Library/Frameworks/R.framework/Versions/4.2-arm64/Resources/lib/libRblas.0.dylib 
>>>>>>
>>>>>> LAPACK: 
>>>>>> /Library/Frameworks/R.framework/Versions/4.2-arm64/Resources/lib/libRlapack.dylib 
>>>>>>
>>>>>>
>>>>>> locale:
>>>>>> [1] en_US.UTF-8/en_US.UTF-8/en_US.UTF-8/C/en_US.UTF-8/en_US.UTF-8
>>>>>>
>>>>>> attached base packages:
>>>>>> [1] tcltk     stats     graphics  grDevices utils datasets  methods
>>>>>> [8] base
>>>>>>
>>>>>> loaded via a namespace (and not attached):
>>>>>> [1] compiler_4.2.0
>>>>>>
>>>>>> ------- snip -------
>>>>>>
>>>>>> Some additional details: The problem occurs both in the R macOS 
>>>>>> console and, if options(help_type="html"), when R is run in a 
>>>>>> terminal window on macOS, but not when options(help_type="text"). 
>>>>>> The former is the default in the Mac R console, the latter when R 
>>>>>> is run in a terminal.
>>>>>>
>>>>>> The problem is apparently new in R 4.2.0 -- it doesn't, e.g., 
>>>>>> occur in R 4.1.3. My apologies for not turning it up earlier.
>>>>>>
>>>>>> I discovered the problem when accessing help in the Rcmdr GUI, 
>>>>>> which uses tcltk, caused R to hang.
>>>>>>
>>>>>> Has anyone else encountered this problem?
>>>>>>
>>>>>> Best,
>>>>>> John
>>>>>> -- 
>>>>>> John Fox, Professor Emeritus
>>>>>> McMaster University
>>>>>> Hamilton, Ontario, Canada
>>>>>> web: https://socialsciences.mcmaster.ca/jfox/
>>>>>>
>>>>>> _______________________________________________
>>>>>> R-SIG-Mac mailing list
>>>>>> R-SIG-Mac using r-project.org
>>>>>> https://stat.ethz.ch/mailman/listinfo/r-sig-mac
>>>>>>
>>>>>
>>>>> _______________________________________________
>>>>> R-SIG-Mac mailing list
>>>>> R-SIG-Mac using r-project.org
>>>>> https://stat.ethz.ch/mailman/listinfo/r-sig-mac
>>>>>
>>>>
-- 
John Fox, Professor Emeritus
McMaster University
Hamilton, Ontario, Canada
web: https://socialsciences.mcmaster.ca/jfox/