>>>>> Hugh Parsonage >>>>> on Tue, 8 Sep 2020 18:08:11 +1000 writes:
> I can only reproduce on Windows, but reliably (both 4.0.0 and 4.0.2): > $> R --vanilla > x <- c(0L, -2e9:2e9) > # > Segmentation fault > Tried to reproduce on Linux but the above worked as expected. Not an > issue merely with the length of the vector; for example, x <- > rep_len(1:10, 1e10) works, though the altrep vector must be long to > reproduce: > x <- c(0L, -1e9:1e9) #ok > Segmentation faults occur with the following too: > x <- (-2e9:2e9) + 1L Your operation would "need" (not in theory, but in practice) to go from altrep to regular vectors. I guess the segfault occurs because of something like this : R asks Windows to hand it a huge amount of memory and Windows replies "ok, here is the memory pointer" and then R tries to write to there, but illegally (because Windows should have told R that it does not really have enough memory for that ..). I cannot reproduce the segmentation fault .. but I can confirm there is a bug there that shows for me on Windows but not on Linux: "My" Windows is on a terminalserver not with too many GB of memory (but then in a version of Windows that recognizes that it cannot get so much memory): ------------------------- Here some transcript (thanks to using Emacs w/ ESS also on Windows) ------------------ R Under development (unstable) (2020-08-24 r79074) -- "Unsuffered Consequences" Copyright (C) 2020 The R Foundation for Statistical Computing Platform: x86_64-w64-mingw32/x64 (64-bit) R ist freie Software und kommt OHNE JEGLICHE GARANTIE. Sie sind eingeladen, es unter bestimmten Bedingungen weiter zu verbreiten. Tippen Sie 'license()' or 'licence()' für Details dazu. R ist ein Gemeinschaftsprojekt mit vielen Beitragenden. Tippen Sie 'contributors()' für mehr Information und 'citation()', um zu erfahren, wie R oder R packages in Publikationen zitiert werden können. Tippen Sie 'demo()' für einige Demos, 'help()' für on-line Hilfe, oder 'help.start()' für eine HTML Browserschnittstelle zur Hilfe. Tippen Sie 'q()', um R zu verlassen. > x <- (-2e9:2e9) + 1L Fehler: kann Vektor der Größe 14.9 GB nicht allozieren > y <- c(0L, -2e9:2e9) Fehler: kann Vektor der Größe 14.9 GB nicht allozieren > Sys.setenv(LANGUAGE="en") > y <- c(0L, -2e9:2e9) Error: cannot allocate vector of size 14.9 Gb > y <- -1e9:4e9 > .Internal(inspect(y)) @0x00000000195a6808 14 REALSXP g0c0 [REF(65535)] -1000000000 : -294967296 (compact) > .Machine$integer.max / 1e9 [1] 2.147484 > y <- -1e6:2.2e9 > .Internal(inspect(y)) @0x000000000a11a5d8 14 REALSXP g0c0 [REF(65535)] -1000000 : -2094967296 (compact) > y <- -1e6:2e9 > .Internal(inspect(y)) @0x000000000a13adf0 13 INTSXP g0c0 [REF(65535)] -1000000 : 2000000000 (compact) > ------------------------- end of transcript ----------------------------------- So indeed, no seg.fault, R notices that it can't get 15 GB of memory. But the bug is bad news: We have *silent* integer overflow happening according to what .Internal(inspect(y)) shows... .... less bad new: Probably the bug is only in the 'internal inspect' code where a format specifier is used in C's printf() that does not work correctly on Windows, at least the way it is currently compiled .. On (64-bit) Linux, I get > y <- -1e9:4e9 ; .Internal(inspect(y)) @7d86388 14 REALSXP g0c0 [REF(65535)] -1000000000 : 4000000000 (compact) > y <- c(0L, y) Error: cannot allocate vector of size 37.3 Gb which seems much better ... until I do find a bug, may again only in the C code underlying .Internal(inspect(.)) : > y <- -1e9:2e9 ; .Internal(inspect(y)) @7d86ac0 13 INTSXP g0c0 [REF(65535)] Error: long vectors not supported yet: ../../../R/src/main/altclasses.c:139 > ______________________________________________ R-devel@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-devel