mnesia:add_backend_type(Alias, Module) after,mnesia:install_fallback("bk.BUP") error

[axpxp]

Describe the bug
mnesia:add_backend_type(Alias, Module) after,If the table is empty,Everything is fine,because Module:init_backend first call.
mnesia:add_backend_type(Alias, Module) after,If there's data in the table,mnesia:backup("bk.BUP") after mnesia:install_fallback("bk.BUP") after mnesia:start(),There will be bugs,because Module:init_backend not call.

To Reproduce
mnesia_rocksdb:create_schema([node()]),
mnesia:start(),
mnesia:add_backend_type(Type, Module)
mnesia:create_table(Name, [{Type, [node()]}),
insert some datas,
mnesia:backup("bk.BUP")
mnesia:install_fallback("bk.BUP")
mnesia:start()---Error reported here

Expected behavior
Backup works fine, thank you

Affected versions
OTP 25 26.

Additional context

[axpxp]

If you don't understand anything, feel free to ask me. I check online every day

[axpxp]

@IngelaAndin please help，thanks.

[IngelaAndin]

@axpxp Well yes it seems like you found a bug in an area of the code that is not much used (at least not by us). Of course it would be nice to get it fixed, but unfortunately it will not be a high priority for us.

[MarkoMin]

@axpxp What module are you using in mnesia:add_backend_type/2? Can you paste error message you get?

[axpxp]

@axpxp What module are you using in mnesia:add_backend_type/2? Can you paste error message you get?

erlang fallback execution sequence error

[axpxp]

@IngelaAndin I have sorted out the test code and can send it to you. As long as you test it, you will know. Please help me, thank you very much

[axpxp]

@IngelaAndin Please help,thank you.

[IngelaAndin]

@axpxp There is a plan for some of my co-workers to start looking at this. I see you already had some communication.

[axpxp]

@axpxp There is a plan for some of my co-workers to start looking at this. I see you already had some communication.

Thank you very, very much

[Mikaka27]

Ignore deleted comment, it was an error in fake external_backend implementation.
I cannot reproduce your problem with the provided steps, could you help?

Here is my attempt:
maint-26...Mikaka27:otp:michal/mnesia/issue-8045

[axpxp]

Please list the specific test steps, including where to download which version, thank you.I'm a novice.

[axpxp]

Please send me a download link to test the version of this problem, thank you

[Mikaka27]

I'm trying to reproduce your problem in a testcase here, but no success so far:
Mikaka27/otp@maint...Mikaka27:otp:michal/mnesia/issue-8045

If you reproduce this it would be good if you could paste the error message with stacktrace.
I've tried searching this repository, and mnesia_rocksdb repository for "erlang fallback execution sequence error", but there is no such error message there.

[axpxp]

Eshell V14.2.1 (press Ctrl+G to abort, type help(). for help)
([email protected])1> mnesia_rocksdb_fallback:run().
Warning: ct_logs not started
Delete schema: okWarning: ct_logs not started
Create schema: okWarning: ct_logs not started
Mnesia start: ok*****************************************
loading backup bup0.BUP
stopping
=INFO REPORT==== 15-Nov-2024::12:11:01.344000 ===
application: mnesia
exited: stopped
type: temporary

starting
WaitRes = ok

---

loading backup bup1.BUP
stopping
=INFO REPORT==== 15-Nov-2024::12:11:05.278000 ===
application: mnesia
exited: stopped
type: temporary

starting
=CRASH REPORT==== 15-Nov-2024::12:11:08.343000 ===
crasher:
initial call: mnesia_rocksdb:init/1
pid: <0.262.0>
registered_name: []
exception exit: {noproc,
{gen_server,call,
[mnesia_rocksdb_admin,
{rdb,{get_ref,t}},
infinity]}}
in function gen_server:call/3 (gen_server.erl, line 419)
in call from mnesia_rocksdb_admin:call/3 (src/mnesia_rocksdb_admin.erl, line 338)
in call from mnesia_rocksdb:init/1 (src/mnesia_rocksdb.erl, line 786)
in call from gen_server:init_it/2 (gen_server.erl, line 980)
in call from gen_server:init_it/6 (gen_server.erl, line 935)
ancestors: [mnesia_ext_sup,mnesia_sup,<0.243.0>]
message_queue_len: 0
messages: []
links: [<0.246.0>]
dictionary: []
trap_exit: true
status: running
heap_size: 376
stack_size: 28
reductions: 175
neighbours:

=ERROR REPORT==== 15-Nov-2024::12:11:10.378000 ===
Mnesia('[email protected]'): ** ERROR ** (core dumped to file: "c:/Users/Administrator/Desktop/111111/mnesia_test/config/[email protected]_1731_643870_376000")
** FATAL ** mnesia_tm crashed: {{"Cannot start from fallback",
{{badmatch,
{error,
{{noproc,
{gen_server,call,
[mnesia_rocksdb_admin,
{rdb,{get_ref,t}},
infinity]}},
{child,undefined,t,
{mnesia_rocksdb,start_proc,
[rdb,t,set,'mnesia_ext_proc_t-_tab',
[{name,t},
{type,set},
{ram_copies,[]},
{disc_copies,[]},
{disc_only_copies,[]},
{rdb,['[email protected]']},
{load_order,0},
{access_mode,read_write},
{majority,false},
{index,[{3,ordered}]},
{snmp,[]},
{local_content,false},
{record_name,t},
{attributes,[k,v]},
{user_properties,
[{mrdb_encoding,
{term,{value,term}}}]},
{frag_properties,[]},
{storage_properties,[]},
{cookie,
{{17316438602540000,
-576460752303423483,1},
'[email protected]'}},
{version,{{2,0},[]}}],
[]]},
transient,false,120000,worker,
[mnesia_rocksdb]}}}},
[{mnesia_rocksdb,load_table,4,
[{file,"src/mnesia_rocksdb.erl"},
{line,446}]},
{mnesia_bup,
'-disc_only_open_fun/2-fun-1-',5,
[{file,"mnesia_bup.erl"},{line,976}]},
{mnesia_bup,restore_tables,5,
[{file,"mnesia_bup.erl"},{line,786}]},
{mnesia_bup,iter,7,
[{file,"mnesia_bup.erl"},{line,125}]},
{mnesia_bup,iterate,4,
[{file,"mnesia_bup.erl"},{line,86}]},
{mnesia_bup,do_fallback_start,2,
[{file,"mnesia_bup.erl"},{line,742}]},
{mnesia_bup,tm_fallback_start,1,
[{file,"mnesia_bup.erl"},{line,723}]},
{mnesia_tm,init,1,
[{file,"mnesia_tm.erl"},{line,90}]}]}},
[{mnesia_bup,tm_fallback_start,1,
[{file,"mnesia_bup.erl"},{line,727}]},
{mnesia_tm,init,1,
[{file,"mnesia_tm.erl"},{line,90}]},
{mnesia_sp,init_proc,4,
[{file,"mnesia_sp.erl"},{line,34}]},
{proc_lib,init_p_do_apply,3,
[{file,"proc_lib.erl"},{line,241}]}]} state: [<0.247.0>]

=CRASH REPORT==== 15-Nov-2024::12:11:20.384000 ===
crasher:
initial call: gen_event:init_it/6
pid: <0.245.0>
registered_name: mnesia_event
exception exit: killed
in function gen_event:terminate_server/4 (gen_event.erl, line 592)
ancestors: [mnesia_sup,<0.243.0>]
message_queue_len: 1
messages: [{'EXIT',<0.249.0>,killed}]
links: []
dictionary: []
trap_exit: true
status: running
heap_size: 6772
stack_size: 28
reductions: 25103
neighbours:

WaitRes = {error,{node_not_running,'[email protected]'}}
=CRASH REPORT==== 15-Nov-2024::12:11:20.384000 ===
crasher:
initial call: application_master:init/4
pid: <0.242.0>
registered_name: []
exception exit: {killed,{mnesia_app,start,[normal,[]]}}
in function application_master:init/4 (application_master.erl, line 142)
ancestors: [<0.241.0>]
message_queue_len: 1
messages: [{'EXIT',<0.243.0>,normal}]
links: [<0.241.0>,<0.44.0>]
dictionary: []
trap_exit: true
status: running
heap_size: 233
stack_size: 28
reductions: 166
neighbours:

=INFO REPORT==== 15-Nov-2024::12:11:20.385000 ===
application: mnesia
exited: {killed,{mnesia_app,start,[normal,[]]}}
type: temporary

=ERROR REPORT==== 15-Nov-2024::12:11:20.393000 ===
** Generic server mnesia_recover terminating
** Last message in was {'EXIT',<0.247.0>,killed}
** When Server state == {state,<0.247.0>,undefined,undefined,undefined,0,
false,false,[]}
** Reason for termination ==
** killed

=ERROR REPORT==== 15-Nov-2024::12:11:20.394000 ===
** Generic server mnesia_monitor terminating
** Last message in was {'EXIT',<0.247.0>,killed}
** When Server state == {state,<0.247.0>,[],[],false,[],undefined,[],[]}
** Reason for termination ==
** killed

=CRASH REPORT==== 15-Nov-2024::12:11:20.394000 ===
crasher:
initial call: mnesia_recover:init/1
pid: <0.251.0>
registered_name: mnesia_recover
exception exit: killed
in function gen_server:decode_msg/9 (gen_server.erl, line 1049)
ancestors: [mnesia_kernel_sup,mnesia_sup,<0.243.0>]
message_queue_len: 0
messages: []
links: []
dictionary: []
trap_exit: true
status: running
heap_size: 1598
stack_size: 28
reductions: 3830
neighbours:

=CRASH REPORT==== 15-Nov-2024::12:11:20.394000 ===
crasher:
initial call: mnesia_monitor:init/1
pid: <0.248.0>
registered_name: mnesia_monitor
exception exit: killed
in function gen_server:decode_msg/9 (gen_server.erl, line 1049)
ancestors: [mnesia_kernel_sup,mnesia_sup,<0.243.0>]
message_queue_len: 0
messages: []
links: []
dictionary: []
trap_exit: true
status: running
heap_size: 1598
stack_size: 28
reductions: 5640
neighbours:

** exception exit: {aborted,{no_exists,[t,{t,'',''}]}}
in function mnesia:abort/1 (mnesia.erl, line 362)
in call from mnesia_rocksdb_fallback:run/0 (test/mnesia_rocksdb_fallback.erl, line 52)

[Mikaka27]

@axpxp could you try if code from this PR: #9152 resolves the issue for you in mnesia_rocksdb?
Be aware that it's not finished yet, and I'm not sure if that's the correct way to fix this.

[axpxp]

new error，otp_win64_27.1.3.exe/otp_win64_28.0-rc0.exe the generated file is incorrect

version25 after executing the mnesia:create_table method：

otp_win64_27.1.3.exe/otp_win64_28.0-rc0.exe after executing the mnesia:create_table method：

There are still mistakes.

#9152

b1()-> ok = mnesia:backup("bk.BUP") . b2()-> io:fwrite("loading backup ~s~n", ["bk.BUP"]), ok = mnesia:install_fallback("bk.BUP"), timer:sleep(2000), io:fwrite("stopping~n", []), mnesia:stop(), timer:sleep(3000), io:fwrite("starting~n", []), mnesia:start(), mnesia_rocksdb:register(), timer:sleep(3000), WaitRes = mnesia:wait_for_tables([rdb_222], 5000), io:fwrite("WaitRes = ~p~n", [WaitRes])

[Execute b1(), then b2(), and then an error is reported]

loading backup bk.BUP
stopping
[admin shutdown]Application: mnesia. Exited: stopped. Type: temporary.
starting
Supervisor: {local,mnesia_sup}. Started: id=mnesia_event,pid=<0.189.0>.
Supervisor: {local,mnesia_sup}. Started: id=mnesia_ext_sup,pid=<0.190.0>.
Supervisor: {local,mnesia_kernel_sup}. Started: id=mnesia_monitor,pid=<0.192.0>.
Supervisor: {local,mnesia_kernel_sup}. Started: id=mnesia_subscr,pid=<0.193.0>.
Supervisor: {local,mnesia_kernel_sup}. Started: id=mnesia_locker,pid=<0.194.0>.
Supervisor: {local,mnesia_kernel_sup}. Started: id=mnesia_recover,pid=<0.195.0>.
=============init_backend
============= AAA mnesia_rocksdb_admin ensure_started
============= BBB mnesia_rocksdb_admin do_start
Supervisor: {local,mnesia_ext_sup}. Started: id=mnesia_rocksdb_admin,pid=<0.199.0>.
=============add_aliases
=============init_backend
============= AAA mnesia_rocksdb_admin ensure_started
===========【admin load add_aliases】
Generic server mnesia_rocksdb_admin terminating. Reason: {{badmatch,{error,{db_open,"IO error: No such file or directory: Failed to open NewSequentialFilec:/Users/Administrator/Desktop/111111/666666/testr/config/mnesia/mnesia_rocksdb-rocksdb_copies-db.extrdb/CURRENT: ϵͳÕÒ²»µ½Ö¸¶¨µÄÎļþ¡£\r\n"}}},[{mnesia_rocksdb_admin,open_db,5,[{file,"src/mnesia_rocksdb_admin.erl"},{line,1508}]},{mnesia_rocksdb_admin,try_load_admin_db,3,[{file,"src/mnesia_rocksdb_admin.erl"},{line,429}]},{lists,foldl,3,[{file,"lists.erl"},{line,2146}]},{mnesia_rocksdb_admin,handle_call,3,[{file,"src/mnesia_rocksdb_admin.erl"},{line,467}]},{gen_server,try_handle_call,4,[{file,"gen_server.erl"},{line,2381}]},{gen_server,handle_msg,6,[{file,"gen_server.erl"},{line,2410}]},{proc_lib,init_p_do_apply,3,[{file,"proc_lib.erl"},{line,329}]}]}. Last message: {[],{add_aliases,[rocksdb_copies]}}. State: {st,#{},#{},[]}. Client mnesia_tm stacktrace: [{gen,do_call,4,[{file,"gen.erl"},{line,241}]},{gen_server,call,3,[{file,"gen_server.erl"},{line,1218}]},{mnesia_rocksdb_admin,call,3,[{file,"src/mnesia_rocksdb_admin.erl"},{line,343}]},{mnesia_schema,init_backends,1,[{file,"mnesia_schema.erl"},{line,177}]}].
crasher: initial call: mnesia_rocksdb_admin:init/1, pid: <0.199.0>, registered_name: mnesia_rocksdb_admin, error: {{badmatch,{error,{db_open,"IO error: No such file or directory: Failed to open NewSequentialFilec:/Users/Administrator/Desktop/111111/666666/testr/config/mnesia/mnesia_rocksdb-rocksdb_copies-db.extrdb/CURRENT: ϵͳÕÒ²»µ½Ö¸¶¨µÄÎļþ¡£\r\n"}}},[{mnesia_rocksdb_admin,open_db,5,[{file,"src/mnesia_rocksdb_admin.erl"},{line,1508}]},{mnesia_rocksdb_admin,try_load_admin_db,3,[{file,"src/mnesia_rocksdb_admin.erl"},{line,429}]},{lists,foldl,3,[{file,"lists.erl"},{line,2146}]},{mnesia_rocksdb_admin,handle_call,3,[{file,"src/mnesia_rocksdb_admin.erl"},{line,467}]},{gen_server,try_handle_call,4,[{file,"gen_server.erl"},{line,2381}]},{gen_server,handle_msg,6,[{file,"gen_server.erl"},{line,2410}]},{proc_lib,init_p_do_apply,3,[{file,"proc_lib.erl"},{line,329}]}]}, ancestors: [mnesia_ext_sup,mnesia_sup,<0.187.0>], message_queue_len: 0, messages: [], links: [<0.190.0>], dictionary: [], trap_exit: true, status: running, heap_size: 10958, stack_size: 29, reductions: 34416; neighbours:
Supervisor: {local,mnesia_ext_sup}. Context: child_terminated. Reason: {{badmatch,{error,{db_open,"IO error: No such file or directory: Failed to open NewSequentialFilec:/Users/Administrator/Desktop/111111/666666/testr/config/mnesia/mnesia_rocksdb-rocksdb_copies-db.extrdb/CURRENT: ϵͳÕÒ²»µ½Ö¸¶¨µÄÎļþ¡£\r\n"}}},[{mnesia_rocksdb_admin,open_db,5,[{file,"src/mnesia_rocksdb_admin.erl"},{line,1508}]},{mnesia_rocksdb_admin,try_load_admin_db,3,[{file,"src/mnesia_rocksdb_admin.erl"},{line,429}]},{lists,foldl,3,[{file,"lists.erl"},{line,2146}]},{mnesia_rocksdb_admin,handle_call,3,[{file,"src/mnesia_rocksdb_admin.erl"},{line,467}]},{gen_server,try_handle_call,4,[{file,"gen_server.erl"},{line,2381}]},{gen_server,handle_msg,6,[{file,"gen_server.erl"},{line,2410}]},{proc_lib,init_p_do_apply,3,[{file,"proc_lib.erl"},{line,329}]}]}. Offender: id=mnesia_rocksdb_admin,pid=<0.199.0>.
Supervisor: {local,mnesia_ext_sup}. Started: id=mnesia_rocksdb_admin,pid=<0.200.0>.
Mnesia('[email protected]'): ** ERROR ** (core dumped to file: "c:/Users/Administrator/Desktop/111111/666666/testr/config/[email protected]_1733_738528_19000"), ** FATAL ** mnesia_tm crashed: {{{{badmatch,{error,{db_open,"IO error: No such file or directory: Failed to open NewSequentialFilec:/Users/Administrator/Desktop/111111/666666/testr/config/mnesia/mnesia_rocksdb-rocksdb_copies-db.extrdb/CURRENT: ϵͳÕÒ²»µ½Ö¸¶¨µÄÎļþ¡£\r\n"}}},[{mnesia_rocksdb_admin,open_db,5,[{file,"src/mnesia_rocksdb_admin.erl"},{line,1508}]},{mnesia_rocksdb_admin,try_load_admin_db,3,[{file,"src/mnesia_rocksdb_admin.erl"},{line,429}]},{lists,foldl,3,[{file,"lists.erl"},{line,2146}]},{mnesia_rocksdb_admin,handle_call,3,[{file,"src/mnesia_rocksdb_admin.erl"},{line,467}]},{gen_server,try_handle_call,4,[{file,"gen_server.erl"},{line,2381}]},{gen_server,handle_msg,6,[{file,"gen_server.erl"},{line,2410}]},{proc_lib,init_p_do_apply,3,[{file,"proc_lib.erl"},{line,329}]}]},{gen_server,call,[mnesia_rocksdb_admin,{[],{add_aliases,[rocksdb_copies]}},infinity]}},[{gen_server,call,3,[{file,"gen_server.erl"},{line,1222}]},{mnesia_rocksdb_admin,call,3,[{file,"src/mnesia_rocksdb_admin.erl"},{line,343}]},{mnesia_schema,init_backends,1,[{file,"mnesia_schema.erl"},{line,177}]},{mnesia_bup,iterate,4,[{file,"mnesia_bup.erl"},{line,91}]},{mnesia_bup,do_fallback_start,2,[{file,"mnesia_bup.erl"},{line,754}]},{mnesia_bup,tm_fallback_start,1,[{file,"mnesia_bup.erl"},{line,735}]},{mnesia_tm,init,1,[{file,"mnesia_tm.erl"},{line,91}]},{mnesia_sp,init_proc,4,[{file,"mnesia_sp.erl"},{line,35}]}]} state: [<0.191.0>]
Application: mnesia. Exited: {killed,{mnesia_app,start,[normal,[]]}}. Type: temporary.
Generic server mnesia_monitor terminating. Reason: killed. Last message: {'EXIT',<0.191.0>,killed}. State: {state,<0.191.0>,[],[],false,[],undefined,[],[]}.
Generic server mnesia_rocksdb_admin terminating. Reason: killed. Last message: {'EXIT',<0.190.0>,killed}. State: {st,#{},#{},[]}.
Generic server mnesia_recover terminating. Reason: killed. Last message: {'EXIT',<0.191.0>,killed}. State: {state,<0.191.0>,undefined,undefined,undefined,0,false,false,[]}.
crasher: initial call: application_master:init/3, pid: <0.186.0>, registered_name: [], exit: {{killed,{mnesia_app,start,[normal,[]]}},[{application_master,init,3,[{file,"application_master.erl"},{line,143}]},{proc_lib,init_p_do_apply,3,[{file,"proc_lib.erl"},{line,329}]}]}, ancestors: [application_controller,<0.10.0>], message_queue_len: 1, messages: [{'EXIT',<0.187.0>,normal}], links: [<0.45.0>], dictionary: [], trap_exit: true, status: running, heap_size: 376, stack_size: 29, reductions: 69; neighbours:
crasher: initial call: mnesia_monitor:init/1, pid: <0.192.0>, registered_name: mnesia_monitor, exit: {killed,[{gen_server,decode_msg,9,[{file,"gen_server.erl"},{line,2299}]},{proc_lib,init_p_do_apply,3,[{file,"proc_lib.erl"},{line,329}]}]}, ancestors: [mnesia_kernel_sup,mnesia_sup,<0.187.0>], message_queue_len: 0, messages: [], links: [], dictionary: [], trap_exit: true, status: running, heap_size: 2586, stack_size: 29, reductions: 7659; neighbours:
crasher: initial call: gen_event:init_it/6, pid: <0.189.0>, registered_name: mnesia_event, exit: {killed,[{gen_event,terminate_server,4,[{file,"gen_event.erl"},{line,1694}]},{proc_lib,init_p_do_apply,3,[{file,"proc_lib.erl"},{line,329}]}]}, ancestors: [mnesia_sup,<0.187.0>], message_queue_len: 0, messages: [], links: [], dictionary: [], trap_exit: true, status: running, heap_size: 6772, stack_size: 29, reductions: 46717; neighbours:
crasher: initial call: mnesia_recover:init/1, pid: <0.195.0>, registered_name: mnesia_recover, exit: {killed,[{gen_server,decode_msg,9,[{file,"gen_server.erl"},{line,2299}]},{proc_lib,init_p_do_apply,3,[{file,"proc_lib.erl"},{line,329}]}]}, ancestors: [mnesia_kernel_sup,mnesia_sup,<0.187.0>], message_queue_len: 0, messages: [], links: [], dictionary: [], trap_exit: true, status: running, heap_size: 1598, stack_size: 29, reductions: 6057; neighbours:
crasher: initial call: mnesia_rocksdb_admin:init/1, pid: <0.200.0>, registered_name: mnesia_rocksdb_admin, exit: {killed,[{gen_server,decode_msg,9,[{file,"gen_server.erl"},{line,2299}]},{proc_lib,init_p_do_apply,3,[{file,"proc_lib.erl"},{line,329}]}]}, ancestors: [mnesia_ext_sup,mnesia_sup,<0.187.0>], message_queue_len: 0, messages: [], links: [], dictionary: [], trap_exit: true, status: running, heap_size: 2586, stack_size: 29, reductions: 5052; neighbours:
WaitRes = {error,{node_not_running,'[email protected]'}}
ok

[axpxp]

The last one has been updated, please check

[Mikaka27]

I've created aeternity/mnesia_rocksdb#60, we need changes in mnesia_rocksdb to make it work.

[axpxp]

Thank you very much
otp_win64_27.1.3.exe/otp_win64_28.0-rc0.exe these two version after executing the mnesia:create_table method, the database files created are incorrect
(The problem occurred before any backup related operations were performed)
Please refer to
#8045 (comment)