ASKSAGE: Sage Q&A Forum - RSS feedhttps://ask.sagemath.org/questions/Q&A Forum for SageenCopyright Sage, 2010. Some rights reserved under creative commons license.Thu, 05 Nov 2015 17:41:53 +0100Unhandled SIGSEGV in Sage 6.8https://ask.sagemath.org/question/29538/unhandled-sigsegv-in-sage-68/I am trying to use python multiprocessing to start worker threads that execute a complex algorithm and produce rows of a matrix. Along the way, worker threads attempt to row reduce the rows they have produced using the echelonize() method.
This works in some cases. However, when working with a 9 x 860 matrix over QQ, the worker thread crashes with
------------------------------------------------------------------------
Unhandled SIGSEGV: A segmentation fault occurred in Sage.
This probably occurred because a *compiled* component of Sage has a bug
in it and is not properly wrapped with sig_on(), sig_off().
Sage will now terminate.
------------------------------------------------------------------------
If I comment out the echelonize() call, the crash does not happen.
I pickled the matrix and loaded into an interactive sage session and echelonize() succeeded.
Any suggestions for how to debug this situation are appreciated.
Vince
Wed, 23 Sep 2015 04:34:56 +0200https://ask.sagemath.org/question/29538/unhandled-sigsegv-in-sage-68/Comment by kcrisman for <p>I am trying to use python multiprocessing to start worker threads that execute a complex algorithm and produce rows of a matrix. Along the way, worker threads attempt to row reduce the rows they have produced using the echelonize() method.</p>
<p>This works in some cases. However, when working with a 9 x 860 matrix over QQ, the worker thread crashes with </p>
<pre><code>------------------------------------------------------------------------
Unhandled SIGSEGV: A segmentation fault occurred in Sage.
This probably occurred because a *compiled* component of Sage has a bug
in it and is not properly wrapped with sig_on(), sig_off().
Sage will now terminate.
------------------------------------------------------------------------
</code></pre>
<p>If I comment out the echelonize() call, the crash does not happen.</p>
<p>I pickled the matrix and loaded into an interactive sage session and echelonize() succeeded.</p>
<p>Any suggestions for how to debug this situation are appreciated.</p>
<p>Vince</p>
https://ask.sagemath.org/question/29538/unhandled-sigsegv-in-sage-68/?comment=29544#post-id-29544I think we might need a little more information to help. Have you tried with the Sage debugger (`sage -gdb` or something like that)?Wed, 23 Sep 2015 17:29:17 +0200https://ask.sagemath.org/question/29538/unhandled-sigsegv-in-sage-68/?comment=29544#post-id-29544Answer by Jeroen Demeyer for <p>I am trying to use python multiprocessing to start worker threads that execute a complex algorithm and produce rows of a matrix. Along the way, worker threads attempt to row reduce the rows they have produced using the echelonize() method.</p>
<p>This works in some cases. However, when working with a 9 x 860 matrix over QQ, the worker thread crashes with </p>
<pre><code>------------------------------------------------------------------------
Unhandled SIGSEGV: A segmentation fault occurred in Sage.
This probably occurred because a *compiled* component of Sage has a bug
in it and is not properly wrapped with sig_on(), sig_off().
Sage will now terminate.
------------------------------------------------------------------------
</code></pre>
<p>If I comment out the echelonize() call, the crash does not happen.</p>
<p>I pickled the matrix and loaded into an interactive sage session and echelonize() succeeded.</p>
<p>Any suggestions for how to debug this situation are appreciated.</p>
<p>Vince</p>
https://ask.sagemath.org/question/29538/unhandled-sigsegv-in-sage-68/?answer=30487#post-id-30487Could it be that you're running out of memory and Sage doesn't handle this properly? Thu, 05 Nov 2015 17:41:53 +0100https://ask.sagemath.org/question/29538/unhandled-sigsegv-in-sage-68/?answer=30487#post-id-30487