GHC: Ticket #7076: Crash with eager blackholing
http://ghc.haskell.org/trac/ghc/ticket/7076
<p>
In the context of the Tamarin prover (<a class="ext-link" href="https://github.com/tamarin-prover/tamarin-prover"><span class="icon"></span>https://github.com/tamarin-prover/tamarin-prover</a>), I am consistently getting segfaults with -feager-blackholing and -fthreaded both switched on. Without eager blackholing (i.e., just -fthreaded), these segfaults are gone.
</p>
<p>
The crash only occurs only when using the GUI, which is implemented as an integrated Yesod web application. Thus the features that we use are Template Haskell, Quasi Quoting, and calling to system processes like the <a class="ext-link" href="http://www.graphviz.org/"><span class="icon"></span>http://www.graphviz.org/</a> 'dot' tool for rendering graphs. We also use one 'unsafePerformIO' for interacting with an instance of another process that we use as an AC-unification oracle. This interaction is protected by an 'MVar' and has been working for over a year now. I'm just mentioning it to simplify thinking about the possible reasons why -feager-blackholing leads to segfaults.
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<p>
The codebase of the prover is rather large and I'm sorry that I cannot provide a small test case. Are there any options to find out more precisely where the program crashes?
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http://ghc.haskell.org/trac/ghc/ticket/7076
Trac 1.2.2simonmarThu, 02 Aug 2012 10:29:40 GMTstatus changed; difficulty set
http://ghc.haskell.org/trac/ghc/ticket/7076#comment:1
http://ghc.haskell.org/trac/ghc/ticket/7076#comment:1
<ul>
<li><strong>status</strong>
changed from <em>new</em> to <em>infoneeded</em>
</li>
<li><strong>difficulty</strong>
set to <em>Unknown</em>
</li>
</ul>
<p>
This could be the same as <a class="closed ticket" href="http://ghc.haskell.org/trac/ghc/ticket/6146" title="#6146: bug: Segmentation fault with eager blackholing (closed: fixed)">#6146</a>, because that fix didn't make it into 7.4.2. Are you able to test with that fix, or with a recent HEAD?
</p>
TicketSimonMeierSun, 05 Aug 2012 20:38:59 GMT
http://ghc.haskell.org/trac/ghc/ticket/7076#comment:2
http://ghc.haskell.org/trac/ghc/ticket/7076#comment:2
<p>
It seems likely that it is the same as <a class="closed ticket" href="http://ghc.haskell.org/trac/ghc/ticket/6146" title="#6146: bug: Segmentation fault with eager blackholing (closed: fixed)">#6146</a>. The segfaults happened at exactly the sam place for 7.4.1 and 7.4.2. I'll see whether I can build HEAD to test that the fix of <a class="closed ticket" href="http://ghc.haskell.org/trac/ghc/ticket/6146" title="#6146: bug: Segmentation fault with eager blackholing (closed: fixed)">#6146</a> works in my case.
</p>
TicketiglooSun, 14 Oct 2012 17:32:43 GMTstatus changed; resolution set
http://ghc.haskell.org/trac/ghc/ticket/7076#comment:3
http://ghc.haskell.org/trac/ghc/ticket/7076#comment:3
<ul>
<li><strong>status</strong>
changed from <em>infoneeded</em> to <em>closed</em>
</li>
<li><strong>resolution</strong>
set to <em>fixed</em>
</li>
</ul>
<p>
Optimistically closing; please re-open if you still have problems with GHC 7.6 or later.
</p>
TicketSimonMeierTue, 16 Oct 2012 10:12:57 GMT
http://ghc.haskell.org/trac/ghc/ticket/7076#comment:4
http://ghc.haskell.org/trac/ghc/ticket/7076#comment:4
<p>
Thanks. I will reopen it if I encounter trouble in the upcoming tests.
</p>
Ticket