bug#36487: Evaluations do not complete since commit c30d117822a8ca26cd8c06c0a3974955bef68eac

[Ludovic Courtès]

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’.