Re: [Valgrind-users] Memcheck in Valgrind 3.8.1 hanging

[Philippe W. <phi...@sk...>]

On Sun, 2014-01-26 at 02:20 +0000, David Carter wrote:
> Hi,
> 
> 
> I've got an issue with memcheck in Valgrind 3.8.1 hanging.  I've left
> processes running for weeks or even months but they don't complete
> (normally these processes run in a few minutes tops, and they were
> working fine with memcheck until a while ago.
> 
> 
> Has anyone seen anything like this before?  Here are the details:
> 
> 
> options:
> 
> --quiet --track-origins=yes --free-fill=7a
> --child-silent-after-fork=yes --fair-sched=no --log-file=/path/to/log
>  --suppressions=/path/to/suppression.file
> 
>  
> 
> strace shows:
> 
> Process 5223 attached - interrupt to quit
> 
> read(1027,
With --fair-sched=no, valgrind uses a pipe to implement a "big lock".
It is however not clear with what you have shown if this 1027 is
the valgrind pipe big lock fd. If yes, then it looks like a bug in
valgrind, as the above read means a thread want to acquire the big
lock to run, but the thread currently holding the lock does not
release it.

Here are various suggestions :
1. when you are in the above blocked state, use gdb+vgdb
   to connect to your process, and examine the state
   of your process (e.g. which thread is doing what)
   (the most likely cause of deadlock/problem is your application, not
   valgrind, at least when looking at your mail with
   a "valgrind developer hat on" :).

2. upgrade to 3.9.0, there are many bugs solved since 3.8.1
   (probably not yours, I do not see anything related to deadlock
    but one never knows).

3. run with a lot more traces e.g.
    -v -v -v -d -d -d --trace-sched=yes --trace-syscalls=yes --trace-signals=yes
  and see if there is some suspicious output.

Philippe