[Gc] I/O issues

Boehm, Hans hans.boehm at hp.com
Tue Sep 9 13:00:37 PDT 2008



> -----Original Message-----
> From: gc-bounces at napali.hpl.hp.com
> [mailto:gc-bounces at napali.hpl.hp.com] On Behalf Of Nicolas Cannasse
> Sent: Monday, September 08, 2008 2:41 AM
> To: gc at napali.hpl.hp.com
> Subject: [Gc] I/O issues
>
> Hello,
>
> Sorry for the multiple messages recently, we could fix a lot
> of things thanks to the help of the people on the list.
>
> We are still experiencing one last issue, which is related to
> I/O functions.
>
> In some rare cases, two of our threads get blocked in a I/O
> function (either recv() , fread() , or __read_nocancel()).
> The two threads are usually unrelated - one can be a MYSQL
> response beeing read while the other is reading a file - but
> they get blocked at the same time. Seems like a deadlock to me.
>
> I wonder is there are some issues with multithreading + linux
> IO + gc signals. Even if the EINTR return values would not be
> handled everywhere, I guess it should still cause an error
> and not cause the threads to block.
>
> Any advice would be appreciated.
I haven't encountered this.  They are blocked even though input is available?  There is no signal handler on the stack, and no sign of the GC being involved in a deadlock?  Does wrapping the call in GC_do_blocking() work around the problem?

Hans

>
> Best,
> Nicolas
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