Add more information to the Observer

[Gsantomaggio]

Add other two panels: first one: 'System limits' and second one 'Limit Statistics'
Show infomations as atom_limit,process_limit,port_limit and counts.

The result is:

[josevalim]

I wonder if it would make sense to group those?

System statistics / limit
-------------------------

Atoms: 11625 / 1048576 (1% used)
Processes: 45 / 262144 (0% used)
...

I am just not sure how the distribution buffer busy limit fits this. :(

[Gsantomaggio]

yes, looks nicer.
about distribution buffer busy limit we can just leave the value without count and percentage

[josevalim]

@Gsantomaggio good call. Especially if we call "Distribution buffer busy limit" and skip the word "limit" in the others.

[Gsantomaggio]

@josevalim sounds good! if it is ok @dgud also for you I will modify it

[dgud]

Test that is doesn't crash if observing an old node, from which the new info is not supplied.

Also test the other way around, old observer receiving the new info,
if that works rebase to maint for inclusion in 20.1.

[Gsantomaggio]

@dgud:

New to old:

➜  otp_2_ob git:(otp_observer_add_info) ✗ ./bin/erl -sname observer
Erlang/OTP 20 [RELEASE CANDIDATE 1] [erts-9.0] [source-0ab4a336d] [64-bit] [smp:4:4] [ds:4:4:10] [async-threads:10] [hipe] [kernel-poll:false]

Eshell V9.0  (abort with ^G)
(observer@mac)1> observer:start().
ok

The observer is:

Attach to an old version:

Old to new

there are not errors or crash

[Gsantomaggio]

@dgud @josevalim WDYT ?

➜  otp_ob git:(otp_observer_add_info) ✗ bin/erl -sname observer +t 30000 +P 1024 +Q 2048
Erlang/OTP 20 [RELEASE CANDIDATE 1] [erts-9.0] [source-9b9ef7765] [64-bit] [smp:8:8] [ds:8:8:10] [async-threads:10] [hipe] [kernel-poll:false]

Eshell V9.0  (abort with ^G)
(observer@mac)1> observer:start().

[josevalim]

@Gsantomaggio great! Shouldn't you flip the values though? 11903 / 30000 instead of 30000 / 11903? Especially as the area title says "statistics / limit"?

[Gsantomaggio]

Ooops yes:) @josevalim

[Gsantomaggio]

bin/erl -sname observer +t 30000 +P 1024 +Q 2048
Erlang/OTP 20 [erts-9.0.1] [source-3de78d02d] [64-bit] [smp:8:8] [ds:8:8:10] [async-threads:10] [hipe] [kernel-poll:false]

Eshell V9.0.1  (abort with ^G)
(observer@mac)1> observer:start().

Global view:

New observer connected to old node version

Old node connected to new observer node

[dgud]

Could you rebase this maint branch.

[Gsantomaggio]

@dgud already did it. Just changed the PR to maint

[dgud]

Oh ok, thanks.

[dgud]

I don't like that you do the string construction in the backend, everywhere else the rawdata is sent,
and the string created in the gui, so I want that code in observer and not in observer_backend.

I think it's better to send the usage and limit as separate key-value pairs from backend and process the info in observer see example get_gc_info/1 in observer_procinfo of using a fun to fill in the info fields.

[Gsantomaggio]

@dgud yes you are right. Let me change it

[Gsantomaggio]

ok @dgud that's much better and it is fully compatible with the old versions:

just one question:
when you use the new to the old is:

Should I replace undefined with something else?

[dgud]

Maybe "Not available" is better?

[Gsantomaggio]

@dgud done:

[dgud]

Otherwise looks good, I will take vacation it in August will merge when I get back.

[dgud]

maybe_convert(undefined) -> "Not available";

[dgud]

Replace with (otherwise C/L will crash if one of them is undefined)
C =:= undefined -> "";
L =:= undefined -> "";

[Gsantomaggio]

@dgud done.
Enjoy your holidays! :)

[dgud]

Indentation should be done with space and not tabs in new or changed code

[Gsantomaggio]

Sorry @dgud,
It should be ok now!