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[bug#30948] [PATCH core-updates] guix: Reap finished child processes in
From: |
Ludovic Courtès |
Subject: |
[bug#30948] [PATCH core-updates] guix: Reap finished child processes in build containers. |
Date: |
Thu, 29 Mar 2018 22:07:05 +0200 |
User-agent: |
Gnus/5.13 (Gnus v5.13) Emacs/25.3 (gnu/linux) |
Hi Carlo,
Carlo Zancanaro <address@hidden> skribis:
> When working on the Shepherd, I found that in the build containers
> processes don't get reaped by pid 1. See
> https://debbugs.gnu.org/cgi/bugreport.cgi?bug=30637#29. This caused
> (and will cause) the Shepherd's tests to fail on some systems.
>
> Our guile-builder script should handle SIGCHLD and then use waitpid to
> reap the child processes. Here's my attempt at a patch to do that.
I would rather install the handler as a phase in gnu-build-system: this
leaves ‘build-expression->derivation’ generic, and also gives us more
flexibility (e.g., we can disable that phase without doing a full
rebuild if needed.) See the patch below.
WDYT?
On my first attempt with:
./pre-inst-env guix build -e '(@@ (gnu packages commencement)
findutils-boot0)'
quickly failed:
--8<---------------cut here---------------start------------->8---
checking for vfork.h... no
checking for fork... yes
checking for vfork... yes
checking for working fork... Backtrace:
In ice-9/boot-9.scm:
yes
checking for working vfork... (cached) yes
checking for strcasecmp... 157: 13 [catch #t #<catch-closure c900a0> ...]
In unknown file:
?: 12 [apply-smob/1 #<catch-closure c900a0>]
In ice-9/boot-9.scm:
63: 11 [call-with-prompt prompt0 ...]
In ice-9/eval.scm:
432: 10 [eval # #]
In ice-9/boot-9.scm:
2320: 9 [save-module-excursion #<procedure cc1b80 at ice-9/boot-9.scm:3961:3
()>]
3966: 8 [#<procedure cc1b80 at ice-9/boot-9.scm:3961:3 ()>]
1645: 7 [%start-stack load-stack #<procedure cbd2c0 at ice-9/boot-9.scm:3957:10
()>]
1650: 6 [#<procedure cc3060 ()>]
In unknown file:
?: 5 [primitive-load
"/gnu/store/pz3jy89ax5jg0j6fnp5n42x4vznga8s3-make-boot0-4.2.1-guile-builder"]
In ice-9/eval.scm:
387: 4 [eval # ()]
In srfi/srfi-1.scm:
619: 3 [for-each #<procedure 1217560 at
/gnu/store/hf8xflikhgsd4hfy9h8s0cjzfqm8f3yb-module-import/guix/build/gnu-build-system.scm:815:12
(expr)> ...]
In
/gnu/store/hf8xflikhgsd4hfy9h8s0cjzfqm8f3yb-module-import/guix/build/gnu-build-system.scm:
819: 2 [#<procedure 1217560 at
/gnu/store/hf8xflikhgsd4hfy9h8s0cjzfqm8f3yb-module-import/guix/build/gnu-build-system.scm:815:12
(expr)> #]
In
/gnu/store/hf8xflikhgsd4hfy9h8s0cjzfqm8f3yb-module-import/guix/build/utils.scm:
614: 1 [invoke
"/gnu/store/g34swjqyw205d15pyra39j56qvyxq9w9-bootstrap-binaries-0/bin/bash" ...]
In unknown file:
?: 0 [system*
"/gnu/store/g34swjqyw205d15pyra39j56qvyxq9w9-bootstrap-binaries-0/bin/bash" ...]
ERROR: In procedure system*:
ERROR: In procedure system*: Interrupted system call
builder for `/gnu/store/hc96d5dcshbdgavpp0j01qnsjf0yf9z5-make-boot0-4.2.1.drv'
failed with exit code 1
--8<---------------cut here---------------end--------------->8---
This is why ‘install-SIGCHLD-handler’ in the patch does nothing on Guile
<= 2.0.9.
Now, we’d need to test it for real with Guile 2.2. I suppose one way to
test without rebuilding it all would be to add this phase explicitly in
a package and try building it with --rounds=10 or something. Would you
like to try that?
Note that we have only a couple of days left before the ‘core-updates’
freeze.
Thanks,
Ludo’.
diff --git a/guix/build/gnu-build-system.scm b/guix/build/gnu-build-system.scm
index be5ad78b9..2c6cb4ad2 100644
--- a/guix/build/gnu-build-system.scm
+++ b/guix/build/gnu-build-system.scm
@@ -51,6 +51,28 @@
(define time-monotonic time-tai))
(else #t))
+(define* (install-SIGCHLD-handler #:rest _)
+ "Handle SIGCHLD signals. Since this code is usually running as PID 1 in the
+build daemon, it has to reap dead processes, hence this procedure."
+ ;; In Guile <= 2.0.9, syscalls could throw EINTR. With these versions,
+ ;; installing a SIGCHLD handler is not safe because we could have uncaught
+ ;; 'system-error' exceptions at any time.
+ (when (or (not (string=? (effective-version) "2.0"))
+ (> (string->number (micro-version)) 9))
+ (format #t "installing SIGCHLD handler in PID ~a\n" (getpid))
+ (sigaction SIGCHLD
+ (lambda _
+ (let loop ()
+ (match (catch 'system-error
+ (lambda ()
+ (waitpid WAIT_ANY WNOHANG))
+ (lambda args
+ '(0 . -)))
+ ((0 . _) #f)
+ ((pid . _) (loop)))))
+ SA_NOCLDSTOP))
+ #t)
+
(define* (set-SOURCE-DATE-EPOCH #:rest _)
"Set the 'SOURCE_DATE_EPOCH' environment variable. This is used by tools
that incorporate timestamps as a way to tell them to use a fixed timestamp.
@@ -758,7 +780,8 @@ which cannot be found~%"
;; Standard build phases, as a list of symbol/procedure pairs.
(let-syntax ((phases (syntax-rules ()
((_ p ...) `((p . ,p) ...)))))
- (phases set-SOURCE-DATE-EPOCH set-paths install-locale unpack
+ (phases install-SIGCHLD-handler
+ set-SOURCE-DATE-EPOCH set-paths install-locale unpack
bootstrap
patch-usr-bin-file
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