#10018: Unhandled SIGSEGV after bnfcertify()
------------------------+---------------------------------------------------
Reporter: jdemeyer | Owner: jdemeyer
Type: defect | Status: new
Priority: critical | Milestone: sage-4.6
Component: c_lib | Keywords: segfault segmentation fault allocatemem
interrupt _sig_on _sig_retry
Author: | Upstream: N/A
Reviewer: | Merged:
Work_issues: |
------------------------+---------------------------------------------------
Changes (by jdemeyer):
* owner: tba => jdemeyer
Old description:
> Do the following in Sage:
> {{{
> sage: K.<z> = CyclotomicField(23); bnf=K.pari_bnf(certify=False)
> sage: bnf.bnfcertify()
> }}}
> After typing the second line {{{bnf.bnfcertify()}}}, hit CTRL-c after 5
> seconds or so (not immediately).
>
> If '''#9893 is not applied''', then the interrupt will never register
> (the computation will continue running).
>
> If '''#9893 is applied''', it will take a long time before the interrupt
> registers, but eventually a `KeyboardInterrupt` will show up. However,
> something is wrong after this `KeyboardInterrupt`, because doing anything
> with PARI, such as typing
> {{{
> K.<z> = CyclotomicField(23)
> }}}
> immediately gives the dreaded
> {{{
> ------------------------------------------------------------
> Unhandled SIGSEGV: A segmentation fault occurred in Sage.
> This probably occurred because a *compiled* component
> of Sage has a bug in it (typically accessing invalid memory)
> or is not properly wrapped with _sig_on, _sig_off.
> You might want to run Sage under gdb with 'sage -gdb' to debug this.
> Sage will now terminate (sorry).
> ------------------------------------------------------------
> }}}
>
> Dependency: #9898 (#9893 has been merged into this patch)
>
> Note that in some cases, after applying this patch, it might be necessary
> to do
> {{{
> sage -ba
> }}}
New description:
Do the following in Sage:
{{{
sage: K.<z> = CyclotomicField(23); bnf=K.pari_bnf(certify=False)
sage: bnf.bnfcertify()
}}}
After typing the second line {{{bnf.bnfcertify()}}}, hit CTRL-c after 5
seconds or so (not immediately).
If '''#9893 is not applied''', then the interrupt will never register (the
computation will continue running).
If '''#9893 is applied''', it will take a long time before the interrupt
registers, but eventually a `KeyboardInterrupt` will show up. However,
something is wrong after this `KeyboardInterrupt`, because doing anything
with PARI, such as typing
{{{
K.<z> = CyclotomicField(23)
}}}
immediately gives the dreaded
{{{
------------------------------------------------------------
Unhandled SIGSEGV: A segmentation fault occurred in Sage.
This probably occurred because a *compiled* component
of Sage has a bug in it (typically accessing invalid memory)
or is not properly wrapped with _sig_on, _sig_off.
You might want to run Sage under gdb with 'sage -gdb' to debug this.
Sage will now terminate (sorry).
------------------------------------------------------------
}}}
Dependency: #9898 (#9893 has been merged into this patch)
In some cases, after applying this patch or changing it, it might be
necessary to do
{{{
sage -ba
}}}
'''NOTE:''' this patch changes the behaviour of buggy Cython code: code
which was previously not interruptible now gives a segmentation fault.
See for example #9564.
--
--
Ticket URL: <http://trac.sagemath.org/sage_trac/ticket/10018#comment:9>
Sage <http://www.sagemath.org>
Sage: Creating a Viable Open Source Alternative to Magma, Maple, Mathematica,
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