Subject: bug#36487: Evaluations do not complete since commit c30d117822a8ca26cd8c06c0a3974955bef68eac

From: Ludovic Courtès <[email-masked]>
Date: Wed, 03 Jul 2019 12:28:53 +0200

Hello,

Chris reported that evaluations “hang” since commit
c30d117822a8ca26cd8c06c0a3974955bef68eac, as can be seen at:

  https://prototype-guix-data-service.cbaines.net/branch/master

as well as:

  https://berlin.guixsd.org/jobset/guix-master (ca. eval. 6171)

The log at <https://prototype-guix-data-service.cbaines.net/job/2674>
shows that it hangs while computing i686 derivations:

--8<---------------cut here---------------start------------->8---
[…]
debug: Starting getting inferior derivations
heap size: 1579.0 MiB
debug: Starting getting derivations for ((x86_64-linux . x86_64-linux))
debug: Finished getting derivations for ((x86_64-linux . x86_64-linux)), took 252 seconds
heap size: 1579.0 MiB
debug: Starting getting derivations for ((i686-linux . i686-linux))
--8<---------------cut here---------------end--------------->8---

If I attach to the ‘guix repl -t machine’ process started by the Cuirass
evaluation process, I see this:

--8<---------------cut here---------------start------------->8---
#0  0x00007fc5248d5fb8 in _dl_update_slotinfo (req_modid=1) at ../elf/dl-tls.c:623
#1  0x00007fc5248d620c in update_get_addr (ti=0x7fc5248ab240) at ../elf/dl-tls.c:799
#2  0x00007fc5248da838 in __tls_get_addr () at ../sysdeps/x86_64/tls_get_addr.S:55
#3  0x00007fc5247ddbe0 in scm_equal_p () from /gnu/store/r658y3cgpnf99nxjxqgjiaizx20ac4k0-guile-2.2.4/lib/libguile-2.2.so.1
#4  0x00007fc5247cda18 in array_compare () from /gnu/store/r658y3cgpnf99nxjxqgjiaizx20ac4k0-guile-2.2.4/lib/libguile-2.2.so.1
#5  0x00007fc5247cd9c7 in array_compare () from /gnu/store/r658y3cgpnf99nxjxqgjiaizx20ac4k0-guile-2.2.4/lib/libguile-2.2.so.1
#6  0x00007fc5247ce675 in scm_array_equal_p () from /gnu/store/r658y3cgpnf99nxjxqgjiaizx20ac4k0-guile-2.2.4/lib/libguile-2.2.so.1
#7  0x00007fc52484891b in scm_i_struct_equalp () from /gnu/store/r658y3cgpnf99nxjxqgjiaizx20ac4k0-guile-2.2.4/lib/libguile-2.2.so.1
#8  0x00007fc5247ddc82 in scm_equal_p () from /gnu/store/r658y3cgpnf99nxjxqgjiaizx20ac4k0-guile-2.2.4/lib/libguile-2.2.so.1
#9  0x00007fc52484891b in scm_i_struct_equalp () from /gnu/store/r658y3cgpnf99nxjxqgjiaizx20ac4k0-guile-2.2.4/lib/libguile-2.2.so.1
#10 0x00007fc52484891b in scm_i_struct_equalp () from /gnu/store/r658y3cgpnf99nxjxqgjiaizx20ac4k0-guile-2.2.4/lib/libguile-2.2.so.1
#11 0x00007fc5247ddc82 in scm_equal_p () from /gnu/store/r658y3cgpnf99nxjxqgjiaizx20ac4k0-guile-2.2.4/lib/libguile-2.2.so.1
…
#101 0x00007fc5247ddc82 in scm_equal_p () from /gnu/store/r658y3cgpnf99nxjxqgjiaizx20ac4k0-guile-2.2.4/lib/libguile-2.2.so.1
#102 0x00007fc52484891b in scm_i_struct_equalp () from /gnu/store/r658y3cgpnf99nxjxqgjiaizx20ac4k0-guile-2.2.4/lib/libguile-2.2.so.1
#103 0x00007fc5247cbb38 in scm_sloppy_assoc () from /gnu/store/r658y3cgpnf99nxjxqgjiaizx20ac4k0-guile-2.2.4/lib/libguile-2.2.so.1
#104 0x00007fc5247f3a92 in scm_hash_fn_ref () from /gnu/store/r658y3cgpnf99nxjxqgjiaizx20ac4k0-guile-2.2.4/lib/libguile-2.2.so.1
#105 0x00007fc524859715 in vm_regular_engine () from /gnu/store/r658y3cgpnf99nxjxqgjiaizx20ac4k0-guile-2.2.4/lib/libguile-2.2.so.1
#106 0x00007fc52485cd6a in scm_call_n () from /gnu/store/r658y3cgpnf99nxjxqgjiaizx20ac4k0-guile-2.2.4/lib/libguile-2.2.so.1
#107 0x00007fc5247e0da7 in scm_primitive_eval () from /gnu/store/r658y3cgpnf99nxjxqgjiaizx20ac4k0-guile-2.2.4/lib/libguile-2.2.so.1
--8<---------------cut here---------------end--------------->8---

and with debugging symbols:

--8<---------------cut here---------------start------------->8---
#3  0x00007fc5247ddc23 in scm_equal_p (x=x@entry="/gnu/store/djh3drjx3hnxlx1bsdnixdm3xjbg5v2c-guile-bootstrap-2.0/bin/guile", 
    y=y@entry="/gnu/store/djh3drjx3hnxlx1bsdnixdm3xjbg5v2c-guile-bootstrap-2.0/bin/guile") at eq.c:290
#4  0x00007fc52484891b in scm_i_struct_equalp (s1="#<struct <derivation>>" = {...}, s2="#<struct <derivation>>" = {...}) at struct.c:693
#5  0x00007fc52484891b in scm_i_struct_equalp (s1="#<struct <derivation-input>>" = {...}, s2="#<struct <derivation-input>>" = {...}) at struct.c:693
#6  0x00007fc5247ddc82 in scm_equal_p (
    x=(#<struct <derivation-input> #<struct <derivation> (("out" . #<struct <derivation-output> "/gnu/store/jc5q4i55hrilibrmacs38skk3cpg2zyb-glibc-bootstrap-0" #f #f #f 3ade740>)) (#<struct <derivation-input> #<struct <derivation> (("out" . #<struct <derivation-output> "/gnu/store/nbi0mzk1dw37nnnahw9akn3bwzwi4gdk-module-import-compiled" #f #f #f 3ae6e00>)) (#<struct <derivation-input> #<struct <derivation> (("out" . #<struct <derivation-output> "/gnu/store/djh3drjx3hnxlx1bsdnixdm3xjbg5v2c-guile-bootstrap-2.0" #f #f #f 3af1b40>)) (#<struct <derivation-input> #<struct <derivation> (("out" . #<struct <derivation-output> "/gnu/store/dgncc5wmw8prxq09y71hqjc6g7rxqvvb-guile-2.0.9.tar.xz" sha256 #vu8(183 87 205 70 191 19 236 172 131 251 142 149 95 181 0 150 172 45 23 187 97 12 168 235 129 111 41 48 42 0 168 70) #f 3af10c0>)) () ("/gnu/store/7f1alh9qj2h0wwy2220npgnmw6pbrkwx-mirrors" "/gnu/store/vwyxp1dq4lb97n6b20w5cqxasy2dai79-content-addressed-mirrors") "i686-linux" "builtin:download" () (("content-addressed-mirrors" . "/gnu/store/vwyxp1dq4lb97n6b20w5cqxasy2dai79-content-addressed-mirrors") ("impureEnvVars" . "http_proxy https_proxy LC_ALL LC_MESSAGES LANG COLUMNS") ("mirrors" . "/gnu/store/7f1alh9qj2h0wwy2220npgnmw6pbrkwx-mirrors") ("out" . "/gnu/store/dgncc5wmw8prxq09y71hqjc6g7rxqvvb-guile-2.0.9.tar.xz") ("preferLocalBuild" . "1") ("url" . "(\"https://alpha.gnu.org/gnu/guix/bootstrap/i686-linux/20131110/guile-2.0.9.tar.xz\" \"http://alpha.gnu.org/gnu/guix/bootstrap/i686-linux/20131110/guile-2.0.9.tar.xz\" \"ftp://alpha.gnu.org/gnu/guix/bootstrap/i686-linux/20131110/guile-2.0.9.tar.xz\" \"http://www.fdn.fr/~lcourtes/software/guix/packages/i686-linux/20131110/guile-2.0.9.tar.xz\" \"http://flashner.co.il/guix/bootstrap/i686-linux/20131110/guile-2.0.9.tar.xz\")")) "/gnu/store/jagg4l53ar1m4hsgqlpisw9i4rq2whzd-guile-2.0.9.tar.xz.drv" 3af14e0> ("out") 3af1780>) ("/gnu/store/d32948vi9bs5mmbnvlczqcgwwdqvygiw-build-bootstrap-guile.sh" "/gnu/store/mzfkrxd4w8vqrmyrx169wj8wyw7r8i37-bash") "i686-linux" "/gnu/store/mzfkrxd4w8 […]
--8<---------------cut here---------------end--------------->8---

So this process is busy comparing deep structures, probably as a
consequence of 5cf4b26d52bcea382d98fb4becce89be9ee37b55.

Indeed, the load on berlin is at above 60 currently, with all these
evaluations processes consuming CPU…

To be continued…

Ludo’.