On 2/21/24 08:01, webmail.gandi.net wrote:
Thank you, Ivan for this investigation. I inspected the R changes file
(https://cran.r-project.org/doc/manuals/r-devel/NEWS.html) and found nothing
about this. I should inspect the sources too!
It could possibly break other Tcl/Tk related stuff. The doc about
Tcl_ServiceAll and Tcl_DoOneEvent is confusing. On one hand, it says when Tcl
is used from an external program, Tcl_ServiceAll should be used in its event
loop instead of Tcl_DoOneEvent (and the change in the latest R versions goes in
that direction). But in the other hand, it is indicated that Tcl_ServiceAll
does not always handle all Tcl events and extra Tcl_DoOneEvent should be called
in this case. I think we spotted one case where Tcl_ServiceAll is not doing its
job correctly. There may be others.
Since the {tcltk} package was working fine with "while (Tcl_DoOneEvent(TCL_DONT_WAIT) && max_ev)
max_ev—;", unless there is a clear performance enhancement with "while (i-- &&
Tcl_ServiceAll())", it would perhaps be wise to revert this back.
Yes, for now I've done that in R-devel. The Tcl documentation is really
hard to follow, but debugging reveals that Tcl_ServiceAll() doesn't
queue new events, as also Ivan reports.
Tomas
Indeed, when I use this on the server side with R 4.3.2:
library(tcltk)
cmd <- r"(
proc accept {chan addr port} { ;# Make a proc to accept connections
puts "$addr:$port says [gets $chan]" ;# Receive a string
puts $chan goodbye ;# Send a string
close $chan ;# Close the socket (automatically
flushes)
} ;#
socket -server accept 12345 ;# Create a server socket)"
.Tcl(cmd)
.Tcl("vwait myvar")
It works again as expected. And vwait is known to call Tcl_DoOneEvent. Of
course, in this case, R is blocked and waits for the `myvar` variable on the
Tcl side. Anyway, the problem seems to be really in Tcl_ServiceAll not catching
all Tcl events.
All the best,
Philippe
..............................................<°}))><........
) ) ) ) )
( ( ( ( ( Prof. Philippe Grosjean
) ) ) ) )
( ( ( ( ( Numerical Ecology
) ) ) ) ) Mons University, Belgium
( ( ( ( (
..............................................................
Le 20 févr. 2024 à 17:13, Ivan Krylov via R-devel <r-devel@r-project.org> a
écrit :
В Tue, 20 Feb 2024 12:27:35 +0100
"webmail.gandi.net" <phgrosj...@sciviews.org> пишет:
When R process #1 is R 4.2.3, it works as expected (whatever version
of R #2). When R process #1 is R 4.3.2, nothing is sent or received
through the socket apparently, but no error is issued and process #2
seems to be able to connect to the socket.
The difference is related to the change in
src/library/tcltk/src/tcltk_unix.c.
In R-4.2.1, the function static void TclSpinLoop(void *data) says:
int max_ev = 100;
/* Tcl_ServiceAll is not enough here, for reasons that escape me */
while (Tcl_DoOneEvent(TCL_DONT_WAIT) && max_ev) max_ev--;
In R-devel, the function instead says:
int i = R_TCL_SPIN_MAX;
while (i-- && Tcl_ServiceAll())
;
Manually calling Tcl_DoOneEvent(0) from the debugger at this point
makes the Tcl code respond to the connection. Tcl_ServiceAll() seems to
be still not enough. I'll try reading Tcl documentation to investigate
this further.
--
Best regards,
Ivan
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