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

[John Fox]

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
>>>
>>
>> _______________________________________________
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>> R-SIG-Mac using r-project.org
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>>
> 
-- 
John Fox, Professor Emeritus
McMaster University
Hamilton, Ontario, Canada
web: https://socialsciences.mcmaster.ca/jfox/