Re: [DynInst_API:] Hung process

[Bill Williams <bill@xxxxxxxxxxx>]

On 02/03/2015 11:12 AM, Josh Stone wrote:
> On 02/03/2015 07:22 AM, Gerard wrote:
> > Hello,
> >
> > I'm experiencing a strange issue while instrumenting a multithreaded
> > application. In essence this application sends data to other processes
> > through TCP/IP connections using multiple threads (one per connection).
> > The problem is that after 39~41 successful connections (always the
> > same), the whole process hangs and I don't know why this happens or how
> > to make it to continue.
> >
> > Without Dyninst instrumentation the process works correctly so I don't
> > know if it is a problem with how I'm using Dyninst or a problem that
> > appears due to using it. If I remove the use of threads the application
> > never hangs and all the data is sent correctly so I guess it is related.
> >
> > Any tips why this could happen?
> There is a compiled constant MAX_THREADS, just 32.  If anything, I'm
> surprised that you got up around 40 before seeing issues. :)
>
> In dyninstAPI_RT, it's used for DYNINST_max_num_threads, and it looks
> like there's code to initialize larger counts dynamically, but I don't
> see anywhere that actually tries to set it higher.  It would have to be
> done as part of process init though.
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Right now, I'd recommend bumping the compiled constant to a reasonable 
safe ceiling. For 9.0, we're going to be eliminating MAX_THREADS, as 
proper TLS-based trampguards make it unnecessary.
I can put together a patch for that and send it out to the list for 
testing and feedback soon; I thought I'd already done that but 
apparently not.
--
--bw

Bill Williams
Paradyn Project
bill@xxxxxxxxxxx