<p>If the MVar was set up prior to the fork, I can imagine things going crazy trying to use it on the ther side of the fork - especially if their were waiting readers or writers while the fork was executing.</p>
<div class="gmail_quote">On Jul 14, 2012 3:01 PM, "Joey Hess" <<a href="mailto:joey@kitenet.net">joey@kitenet.net</a>> wrote:<br type="attribution"><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
I've isolated the hang further to hPipeFrom's use of System.Log.Logger.<br>
Commenting out calls to logging functions makes it reliably run ok. See<br>
the "LINE OF DEATH" in the attached updated test case.<br>
<br>
... And it turns out that System.Log.Logger uses a MVar to hold the<br>
logger information. So I think this points to a MissingH bug, although I<br>
don't yet understand it.<br>
<br>
--<br>
see shy jo<br>
</blockquote></div>