[erlang-questions] Benchmarking Erlang: Deathmatch of gb_trees, dict, ets, mnesia ... and registered names

[Joel Reymont]

%% mnesia ram_copies on two nodes

%% node #1

mothership:opti joelr$ erl -sname 1
(1@REDACTED)1> map6:setup1(['1@REDACTED', '2@REDACTED']).
{atomic,ok}
(1@REDACTED)2> mnesia:info().
...
---> Active tables <---
schema         : with 2        records occupying 553      words of mem
xref           : with 0        records occupying 312      words of mem
...
running db nodes   = ['2@REDACTED','1@REDACTED']
...
[{'1@REDACTED',ram_copies},{'2@REDACTED',ram_copies}] =  
[xref,schema]
5 transactions committed, 0 aborted, 0 restarted, 0 logged to disc
0 held locks, 0 in queue; 0 local transactions, 0 remote
0 transactions waits for other nodes: []
ok

%% node #2

mothership:opti joelr$ erl -sname 2
(2@REDACTED)2> mnesia:start().
ok
(2@REDACTED)3> mnesia:change_config(extra_db_nodes, ['1@REDACTED']).
{ok,['1@REDACTED']}
(2@REDACTED)4> mnesia:info().
...
---> Active tables <---
schema         : with 2        records occupying 553      words of mem
xref           : with 0        records occupying 312      words of mem
...
running db nodes   = ['1@REDACTED','2@REDACTED']
...
[{'1@REDACTED',ram_copies},{'2@REDACTED',ram_copies}] =  
[xref,schema]
5 transactions committed, 0 aborted, 0 restarted, 0 logged to disc
0 held locks, 0 in queue; 0 local transactions, 0 remote
0 transactions waits for other nodes: []
ok

%% node #1

(1@REDACTED)3> map6:test(10000).
Populate: 0.1193
Lookup:   5.0006
ok
(1@REDACTED)4> map6:test(100000).
Populate: 1.4206
Lookup:   5.0003
ok
(1@REDACTED)5> map6:test(1000000).
Populate: 1.8590
Lookup:   5.0009
ok

No difference from ets and mnesia ram_copies on a single node!

Here's proof that we did commit to the other node:

%% node #2

(2@REDACTED)5> mnesia:info().
---> Processes holding locks <---
Lock: {{xref,93850},write,{tid,16678,<5738.84.0>}}
Lock: {{xref,999482},write,{tid,16671,<5738.86.0>}}
---> Participant transactions <---
Tid: 16671 (owned by <5738.86.0>)
with participant objects {commit,'2@REDACTED',presume_commit,
                                  [{{xref,999482},{xref, 
999482,999482},write}],
                                  [],[],[],[],[]}
---> Active tables <---
schema         : with 2        records occupying 553      words of mem
xref           : with 16668    records occupying 186219   words of mem
...
5 transactions committed, 0 aborted, 0 restarted, 0 logged to disc
2 held locks, 0 in queue; 0 local transactions, 1 remote
0 transactions waits for other nodes: []
ok