[erlang-questions] Reading from private ets tables?

[Ulf Wiger]

No, you can't read private ets tables (owned by some other process).

However, in this particular case, mnesia does offer some functions that might be of help.

mnesia:info() prints quite a lot of information, including info about held locks.

Another function: mnesia_locker:get_held_locks():

3> mnesia_locker:get_held_locks().
[]
4> mnesia:create_table(t, []).
{atomic,ok}
5> spawn(fun() -> mnesia:transaction(fun() -> mnesia:write({t,1,a}), timer:sleep(30000) end) end).
<0.55.0>
6> mnesia_locker:get_held_locks().
[{{t,1},write,{tid,4,<0.55.0>}}]
...
7> mnesia_locker:get_held_locks().
[]

Finally, mnesia_lib:dist_coredump() is a big hammer, when all else fails.

BR,
Ulf W

On 18 Oct 2011, at 11:39, Attila Rajmund Nohl wrote:

> Hello!
> 
> Is there a way to read data from private ets tables? I have to debug
> mnesia, but the interesting tables (e.g. mnesia_held_locks) are
> private, so I can't find whose locks are deadlocking.
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Ulf Wiger, CTO, Erlang Solutions, Ltd.
http://erlang-solutions.com