[erlang-questions] Creating a diagnostic memory dump of live erlang VM
Wed Feb 19 14:08:32 CET 2014
You can access these with process_info(Pid, messages) for the mailbox and
sys:get_state(Pid) for the state, respectively.
I also suggest taking a look at recon (http://ferd.github.io/recon/) to
do live debugging in a system.
On 02/19, Vladimir Ralev wrote:
> From what I've seen the crashdump doesn't really have any of the objects in
> the memory. If I have a string stuck in some mailbox or even just state
> inside a gen_server process, can I see it?
> On Wed, Feb 19, 2014 at 7:20 AM, Geoff Cant <nem@REDACTED> wrote:
> > Provided you're prepared to take down the node, you can
> > erlang:halt("crashdump") and you'll get a dump of memory, heaps, tables,
> > ... - erl_crash.dump file.
> > You can view this in a web browser with crashdump_viewer.
> > Crashdump debugging is unfortunate, but extremely useful. I use it on all
> > my production systems.
> > -G
> > > On 18/02/2014, at 16:00, Vladimir Ralev <vladimir.ralev@REDACTED>
> > wrote:
> > >
> > > Hello all,
> > >
> > > As a Java developer I really miss being able to create a "heap dump" of
> > a live Erlang VM where I can see the objects in each process and the
> > current process stack variables/trace. I realise there is no java-like heap
> > in Erlang but there are the processes, mailboxes, stacks, file handles,
> > sockets, ets and so on.
> > >
> > > In Java we can also use query tools to search the heaps for specific
> > identifying strings/numbers/timestamps to find a graph of related objects.
> > You can go find objects by type or find the stack variables for given
> > thread. It would be very useful for understanding the system in production
> > and diagnose issues.
> > >
> > > Would it be possible to have something like this in Erlang or it is
> > fundamentally not allowed?
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