preemption does not work on the Hurd #171

Yelninei commented 2026年02月15日 13:44:42 +01:00

Forwarding guix/guix#2471

The test tests/preemption.scm specifically the

;; assert run-fibers on (race-until 100) terminates
(assert-run-fibers-returns (100) (race-until 100))

never terminates when running the tests on the Hurd causing the tests to hang.

The reason is that in with-interrupts/thread-cputime the interrupt-thread calls clock-nanosleep with a clock from pthread-getcpuclockid which fails with EINVAL.

The exception gets caught by the false-if-exception and the interrupt-thread just dies.

Then in the test the expected interrupt never happens and the test runs forever.

Forwarding https://codeberg.org/guix/guix/issues/2471 The test `tests/preemption.scm` specifically the ``` ;; assert run-fibers on (race-until 100) terminates (assert-run-fibers-returns (100) (race-until 100)) ``` never terminates when running the tests on the Hurd causing the tests to hang. The reason is that in `with-interrupts/thread-cputime` the `interrupt-thread` calls `clock-nanosleep` with a clock from `pthread-getcpuclockid` which fails with EINVAL. The exception gets caught by the `false-if-exception` and the `interrupt-thread` just dies. Then in the test the expected interrupt never happens and the test runs forever.

civodul commented 2026年04月04日 19:33:57 +02:00

I can reproduce the problem on x86_64-gnu from Guix commit f0e22ae62c143fbf00bde368c2adbc848cff5ff5:

ludo@childhurd ~$ guile -L /gnu/store/*-fibers*/share/guile/site/3.0 --no-auto-compile
GNU Guile 3.0.11
Copyright (C) 1995-2024 Free Software Foundation, Inc.
Guile comes with ABSOLUTELY NO WARRANTY; for details type `,show w'.
This program is free software, and you are welcome to redistribute it
under certain conditions; type `,show c' for details.
Enter `,help' for help.
scheme@(guile-user)> ,use(fibers posix-clocks)
scheme@(guile-user)> (pthread-getcpuclockid (pthread-self))
1ドル = 3
scheme@(guile-user)> (clock-nanosleep 1ドル 1000000)
ice-9/boot-9.scm:1705:22: In procedure raise-exception:
Invalid argument

The value returned above is CLOCK_THREAD_CPUTIME_ID.

Currently, in glibc, mach/clock_nanosleep.c reads:

int
__clock_nanosleep (clockid_t clock_id, int flags, const struct timespec *req,
		 struct timespec *rem)
{
 if ((clock_id != CLOCK_REALTIME && clock_id != CLOCK_MONOTONIC)
 || req->tv_sec < 0
 || !valid_nanoseconds (req->tv_nsec)
 || (flags != 0 && flags != TIMER_ABSTIME))
 return EINVAL;

I can reproduce the problem on x86_64-gnu from Guix commit f0e22ae62c143fbf00bde368c2adbc848cff5ff5: ``` ludo@childhurd ~$ guile -L /gnu/store/*-fibers*/share/guile/site/3.0 --no-auto-compile GNU Guile 3.0.11 Copyright (C) 1995-2024 Free Software Foundation, Inc. Guile comes with ABSOLUTELY NO WARRANTY; for details type `,show w'. This program is free software, and you are welcome to redistribute it under certain conditions; type `,show c' for details. Enter `,help' for help. scheme@(guile-user)> ,use(fibers posix-clocks) scheme@(guile-user)> (pthread-getcpuclockid (pthread-self)) 1ドル = 3 scheme@(guile-user)> (clock-nanosleep 1ドル 1000000) ice-9/boot-9.scm:1705:22: In procedure raise-exception: Invalid argument ``` The value returned above is `CLOCK_THREAD_CPUTIME_ID`. Currently, in glibc, `mach/clock_nanosleep.c` reads: ```c int __clock_nanosleep (clockid_t clock_id, int flags, const struct timespec *req, struct timespec *rem) { if ((clock_id != CLOCK_REALTIME && clock_id != CLOCK_MONOTONIC) || req->tv_sec < 0 || !valid_nanoseconds (req->tv_nsec) || (flags != 0 && flags != TIMER_ABSTIME)) return EINVAL; ```

Yelninei commented 2026年04月28日 22:22:42 +02:00

@janneke mentioned on irc that he experienced dynamic-wind* test crash inconsistently on 1.4.3 although I got no problems with that currently.

Signals delivery fails constantly at GC # 189
Signals delivery fails constantly
/gnu/store/d367xck1ml092xgcr95p17dbmfq008h7-bash-minimal-5.2.37/bin/bash: line 6: 13661 Aborted > (core dumped) top_srcdir="/tmp/guix-build-guile-fibers-1.4.3.drv-0/source" ./env /gnu/store/> kg0v4mrk6748xnvba4rbri3di8px4pvg-guile-3.0.9/bin/guile --no-auto-compile -s ${dir}$tst

it looks similar to the crash in #175 (comment) with the "fix".

@janneke mentioned on irc that he experienced `dynamic-wind*` test crash inconsistently on 1.4.3 although I got no problems with that currently. > <janneke> Signals delivery fails constantly at GC # 189 > <janneke> Signals delivery fails constantly > <janneke> /gnu/store/d367xck1ml092xgcr95p17dbmfq008h7-bash-minimal-5.2.37/bin/bash: line 6: 13661 Aborted > (core dumped) top_srcdir="/tmp/guix-build-guile-fibers-1.4.3.drv-0/source" ./env /gnu/store/> kg0v4mrk6748xnvba4rbri3di8px4pvg-guile-3.0.9/bin/guile --no-auto-compile -s ${dir}$tst it looks similar to the crash in https://codeberg.org/guile/fibers/pulls/175#issuecomment-12659694 with the "fix".