aboutsummaryrefslogtreecommitdiffstats
path: root/lib/os_mon/test/memsup_SUITE.erl
blob: 8c31a8c39ac7559af1d41d7f9ebb2507e925a70c (plain) (blame)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
%%
%% %CopyrightBegin%
%%
%% Copyright Ericsson AB 1996-2011. All Rights Reserved.
%%
%% Licensed under the Apache License, Version 2.0 (the "License");
%% you may not use this file except in compliance with the License.
%% You may obtain a copy of the License at
%%
%%     http://www.apache.org/licenses/LICENSE-2.0
%%
%% Unless required by applicable law or agreed to in writing, software
%% distributed under the License is distributed on an "AS IS" BASIS,
%% WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
%% See the License for the specific language governing permissions and
%% limitations under the License.
%%
%% %CopyrightEnd%
%%
-module(memsup_SUITE).
-include_lib("common_test/include/ct.hrl").

%% Test server specific exports
-export([all/0, suite/0]).
-export([init_per_suite/1, end_per_suite/1]).
-export([init_per_testcase/2, end_per_testcase/2]).

%% Test cases
-export([api/1, alarm1/1, alarm2/1, process/1]).
-export([config/1, timeout/1, unavailable/1, port/1]).
-export([otp_5910/1]).

init_per_suite(Config) when is_list(Config) ->
    ok = application:start(os_mon),
    Config.

end_per_suite(Config) when is_list(Config) ->
    ok = application:stop(os_mon),
    Config.

init_per_testcase(_Case, Config) ->
    Config.

end_per_testcase(_Case, _Config) ->
    ok.

suite() ->
    [{ct_hooks,[ts_install_cth]},
     {timetrap,{minutes,1}}].

all() -> 
    All = case test_server:os_type() of
              {unix, sunos} ->
                  [api, alarm1, alarm2, process, config, timeout,
                   unavailable, port];
              {unix, linux} ->
                  [api, alarm1, alarm2, process, timeout];
              _OS -> [api, alarm1, alarm2, process]
          end,
    Bugs = [otp_5910],
    All ++ Bugs.


api(suite) ->
    [];
api(doc) ->
    ["Test of API functions"];
api(Config) when is_list(Config) ->

    %% get_memory_data()
    RegMemData = memsup:get_memory_data(),
    case RegMemData of
        {TotMem, AllBytes, {Pid, PidBytes}} when is_integer(TotMem),
                                                 is_integer(AllBytes),
                                                 is_pid(Pid),
                                                 is_integer(PidBytes) ->
            ok;
        {0, 0, _WorstPid} ->
            ct:fail(first_data_collection_failed);
        _ ->
            ct:fail({bad_return, RegMemData})
    end,

    %% get_system_memory_data()
    ExtMemData = memsup:get_system_memory_data(),
    Tags = [total_memory,
            free_memory,
            system_total_memory,
            largest_free,
            number_of_free,
            free_swap,
            total_swap,
            cached_memory,
            buffered_memory,
            shared_memory],

    true = lists:all(fun({Tag,Value}) when is_atom(Tag),
                                           is_integer(Value) ->
                             lists:member(Tag, Tags);
                        (_) ->
                             false
                     end, ExtMemData),

    %% get_os_wordsize()
    ok = case memsup:get_os_wordsize() of
             32             -> ok;
             64             -> ok;
             unsupported_os -> ok;
             _ -> error
         end,

    %% get_check_interval()
    60000 = memsup:get_check_interval(),

    %% set_check_interval(Minutes)
    ok = memsup:set_check_interval(2),
    120000 = memsup:get_check_interval(),
    {'EXIT',{badarg,_}} =
    (catch memsup:set_check_interval(0.2)),
    120000 = memsup:get_check_interval(),
    ok = memsup:set_check_interval(1),

    %% get_procmem_high_watermark()
    5 = memsup:get_procmem_high_watermark(),

    %% set_procmem_high_watermark()
    ok = memsup:set_procmem_high_watermark(0.1),
    10 = memsup:get_procmem_high_watermark(),
    {'EXIT',{badarg,_}} =
    (catch memsup:set_procmem_high_watermark(-0.1)),
    10 = memsup:get_procmem_high_watermark(),
    ok = memsup:set_procmem_high_watermark(0.05),

    %% get_sysmem_high_watermark()
    80 = memsup:get_sysmem_high_watermark(),

    %% set_sysmem_high_watermark()
    ok = memsup:set_sysmem_high_watermark(0.9),
    90 = memsup:get_sysmem_high_watermark(),
    {'EXIT',{badarg,_}} =
    (catch memsup:set_sysmem_high_watermark(-0.9)),
    90 = memsup:get_sysmem_high_watermark(),
    ok = memsup:set_sysmem_high_watermark(0.8),

    %% get|set_helper_timeout
    30 = memsup:get_helper_timeout(),
    ok = memsup:set_helper_timeout(29),
    29 = memsup:get_helper_timeout(),
    {'EXIT',{badarg,_}} = (catch memsup:set_helper_timeout(31.0)),
    29 = memsup:get_helper_timeout(),
    ok.

%%----------------------------------------------------------------------
%% NOTE: The test case is a bit weak as it will fail if the memory
%% usage changes too much during its course.
%%----------------------------------------------------------------------
alarm1(suite) ->
    [];
alarm1(doc) ->
    ["Test alarms when memsup_system_only==false"];
alarm1(Config) when is_list(Config) ->

    %% If system memory usage is too high, the testcase cannot
    %% be run correctly
    {Total, Alloc, {_Pid,_PidAlloc}} = memsup:get_memory_data(),
    io:format("alarm1: Total: ~p, Alloc: ~p~n", [Total, Alloc]),
    SysUsage = Alloc/Total,
    if
        SysUsage > 0.99 ->
            {skip, sys_mem_too_high};
        true ->
            alarm1(Config, SysUsage)
    end.

alarm1(_Config, SysUsage) ->
    %% Set a long memory check interval, we will force memory checks
    %% instead
    ok = memsup:set_check_interval(60),

    %% Check thresholds
    SysThreshold = (memsup:get_sysmem_high_watermark()/100),
    ProcThreshold = (memsup:get_procmem_high_watermark()/100),

    %% Check if a system alarm already should be set or not
    SysP = if
               SysUsage>SysThreshold -> true;
               SysUsage=<SysThreshold -> false
           end,

    %% If system memory is higher than threshold, make sure the system
    %% alarm is set. Otherwise, make sure it is not set
    case alarm_set(system_memory_high_watermark) of
        {true, []} when SysP ->
            ok;
        false when not SysP ->
            ok;
        _ ->
            ct:fail({sys_alarm, SysUsage, SysThreshold})
    end,

    %% Lower/raise the threshold to clear/set the alarm
    NewSysThreshold = if
                          SysP ->
                              Value = 1.1*SysUsage,
                              if
                                  Value > 0.99 -> 0.99;
                                  true -> Value
                              end;
                          not SysP -> 0.9*SysUsage
                      end,

    ok = memsup:set_sysmem_high_watermark(NewSysThreshold),

    %% Initiate and wait for a new data collection
    ok = force_collection(),

    %% Make sure the alarm is cleared/set
    ct:sleep({seconds,5}),
    case alarm_set(system_memory_high_watermark) of
        {true, []} when not SysP ->
            ok;
        false when SysP ->
            ok;
        _ ->
            ct:fail({sys_alarm, SysUsage, NewSysThreshold})
    end,

    %% Reset the threshold to set/clear the alarm again
    ok = memsup:set_sysmem_high_watermark(SysThreshold),
    ok = force_collection(),
    ct:sleep({seconds,1}),
    case alarm_set(system_memory_high_watermark) of
        {true, []} when SysP ->
            ok;
        false when not SysP ->
            ok;
        _ ->
            ct:fail({sys_alarm, SysUsage, SysThreshold})
    end,

    %% Check memory usage
    {Total2, _, {WorstPid, PidAlloc}} = memsup:get_memory_data(),

    %% Check if a process alarm already should be set or not
    PidUsage = PidAlloc/Total2,
    ProcP = if
                PidUsage>ProcThreshold -> true;
                PidUsage=<ProcThreshold -> false
            end,

    %% Make sure the process alarm is set/not set accordingly
    case alarm_set(process_memory_high_watermark) of
        {true, WorstPid} when ProcP ->
            ok;
        false when not ProcP ->
            ok;
        {true, BadPid1} when ProcP ->
            ct:fail({proc_alarm, WorstPid, BadPid1});
        _ ->
            ct:fail({proc_alarm, PidUsage, ProcThreshold})
    end,

    %% Lower/raise the threshold to clear/set the alarm
    NewProcThreshold = if
                           ProcP -> 1.1*PidUsage;
                           not ProcP -> 0.9*PidUsage
                       end,
    ok = memsup:set_procmem_high_watermark(NewProcThreshold),
    ok = force_collection(),
    ct:sleep({seconds,1}),
    case alarm_set(process_memory_high_watermark) of
        {true, WorstPid} when not ProcP ->
            ok;
        false when ProcP ->
            ok;
        {true, BadPid2} when not ProcP ->
            ct:fail({proc_alarm, WorstPid, BadPid2});
        _ ->
            ct:fail({proc_alarm, PidUsage, ProcThreshold})
    end,

    %% Reset the threshold to clear/set the alarm
    ok = memsup:set_procmem_high_watermark(ProcThreshold),
    ok = force_collection(),
    ct:sleep({seconds,1}),
    case alarm_set(process_memory_high_watermark) of
        {true, WorstPid} when ProcP ->
            ok;
        false when not ProcP ->
            ok;
        {true, BadPid3} when ProcP ->
            ct:fail({proc_alarm, WorstPid, BadPid3});
        _ ->
            ct:fail({proc_alarm, PidUsage, ProcThreshold})
    end,

    %% Reset memory check interval
    ok = memsup:set_check_interval(1),
    ok.

alarm2(suite) ->
    [];
alarm2(doc) ->
    ["Test alarms when memsup_system_only==true"];
alarm2(Config) when is_list(Config) ->

    %% If system memory usage is too high, the testcase cannot
    %% be run correctly
    {Total, Alloc, {_Pid,_PidAlloc}} = memsup:get_memory_data(),
    SysUsage = Alloc/Total,
    if
        SysUsage>0.99 ->
            {skip, sys_mem_too_high};
        true ->
            alarm2(Config, SysUsage)
    end.

alarm2(_Config, _SysUsage) ->

    %% Change memsup_system_only and restart memsup
    ok = application:set_env(os_mon, memsup_system_only, true),
    ok = supervisor:terminate_child(os_mon_sup, memsup),
    {ok, _Memsup1} = supervisor:restart_child(os_mon_sup, memsup),

    %% Set a long memory check interval, we will force memory checks
    %% instead
    ok = memsup:set_check_interval(60),

    %% Check data and thresholds
    {Total, Alloc, undefined} = memsup:get_memory_data(),
    SysThreshold = (memsup:get_sysmem_high_watermark()/100),
    true = is_integer(memsup:get_procmem_high_watermark()),

    %% Check if a system alarm already should be set or not
    SysUsage = Alloc/Total,
    SysP = if
               SysUsage>SysThreshold -> true;
               SysUsage=<SysThreshold -> false
           end,

    %% If system memory is higher than threshold, make sure the system
    %% alarm is set. Otherwise, make sure it is not set
    case alarm_set(system_memory_high_watermark) of
        {true, []} when SysP ->
            ok;
        false when not SysP ->
            ok;
        _ ->
            ct:fail({sys_alarm, SysUsage, SysThreshold})
    end,

    %% Lower/raise the threshold to clear/set the alarm
    NewSysThreshold = if
                          SysP ->
                              Value = 1.1*SysUsage,
                              if
                                  Value > 0.99 -> 0.99;
                                  true -> Value
                              end;
                          not SysP -> 0.9*SysUsage
                      end,

    ok = memsup:set_sysmem_high_watermark(NewSysThreshold),

    %% Initiate and wait for a new data collection
    ok = force_collection(),

    %% Make sure the alarm is cleared/set
    ct:sleep({seconds,1}),
    case alarm_set(system_memory_high_watermark) of
        {true, []} when not SysP ->
            ok;
        false when SysP ->
            ok;
        _ ->
            ct:fail({sys_alarm, SysUsage, NewSysThreshold})
    end,

    %% Reset the threshold to set/clear the alarm again
    ok = memsup:set_sysmem_high_watermark(SysThreshold),
    ok = force_collection(),
    ct:sleep({seconds,1}),
    case alarm_set(system_memory_high_watermark) of
        {true, []} when SysP ->
            ok;
        false when not SysP ->
            ok;
        _ ->
            ct:fail({sys_alarm, SysUsage, SysThreshold})
    end,

    %% Reset memsup_system_only and restart memsup
    %% (memory check interval is then automatically reset)
    ok = application:set_env(os_mon, memsup_system_only, false),
    ok = supervisor:terminate_child(os_mon_sup, memsup),
    {ok, _Memsup2} = supervisor:restart_child(os_mon_sup, memsup),

    ok.

alarm_set(Alarm) ->
    alarm_set(Alarm, alarm_handler:get_alarms()).
alarm_set(Alarm, [{Alarm,Data}|_]) ->
    {true,Data};
alarm_set(Alarm, [_|T]) ->
    alarm_set(Alarm, T);
alarm_set(_Alarm, []) ->
    false.

process(suite) ->
    [];
process(doc) ->
    ["Make sure memsup discovers a process grown very large"];
process(Config) when is_list(Config) ->

    %% Set a long memory check interval, we will force memory checks
    %% instead
    ok = memsup:set_check_interval(60),

    %% Collect data
    MemData = memsup:get_memory_data(),
    io:format("process: memsup:get_memory_data() = ~p~n", [MemData]),
    {_Total,_Free,{_,Bytes}} = MemData,

    %% Start a new process larger than Worst
    WorsePid = spawn(fun() -> new_hog(Bytes) end),
    ct:sleep({seconds,1}),

    %% Initiate and wait for a new data collection
    ok = force_collection(),

    %% Check that get_memory_data() returns updated result
    case memsup:get_memory_data() of
        {_, _, {WorsePid, _MoreBytes}} ->
            ok;
        {_, _, BadWorst} ->
            ct:fail({worst_pid, BadWorst})
    end,

    %% Reset memory check interval
    exit(WorsePid, done),
    ok = memsup:set_check_interval(1),
    ok.

new_hog(Bytes) ->
    WordSize = erlang:system_info(wordsize),
    N = (Bytes+200) div WordSize div 2,
    List = lists:duplicate(N, a),
    new_hog_1(List).

new_hog_1(List) ->
    receive
        _Any -> exit(List)
    end.

config(suite) ->
    [];
config(doc) ->
    ["Test configuration"];
config(Config) when is_list(Config) ->

    %% Change configuration parameters and make sure change is reflected
    %% when memsup is restarted
    ok = application:set_env(os_mon, memory_check_interval, 2),
    ok =
    application:set_env(os_mon, system_memory_high_watermark, 0.9),
    ok =
    application:set_env(os_mon, process_memory_high_watermark, 0.1),
    ok = application:set_env(os_mon, memsup_helper_timeout, 35),
    ok = application:set_env(os_mon, memsup_system_only, true),

    ok = supervisor:terminate_child(os_mon_sup, memsup),
    {ok, _Child1} = supervisor:restart_child(os_mon_sup, memsup),

    120000 = memsup:get_check_interval(),
    90 = memsup:get_sysmem_high_watermark(),
    10 = memsup:get_procmem_high_watermark(),
    35 = memsup:get_helper_timeout(),

    %% Also try this with bad parameter values, should be ignored
    ok = application:set_env(os_mon, memory_check_interval, 0.2),
    ok =
    application:set_env(os_mon, system_memory_high_watermark, -0.9),
    ok =
    application:set_env(os_mon, process_memory_high_watermark,-0.1),
    ok = application:set_env(os_mon, memsup_helper_timeout, 0.35),
    ok = application:set_env(os_mon, memsup_system_only, arne),

    ok = supervisor:terminate_child(os_mon_sup, memsup),
    {ok, _Child2} = supervisor:restart_child(os_mon_sup, memsup),

    60000 = memsup:get_check_interval(),
    80 = memsup:get_sysmem_high_watermark(),
    5 = memsup:get_procmem_high_watermark(),
    30 = memsup:get_helper_timeout(),

    %% Reset configuration parameters
    ok = application:set_env(os_mon, memory_check_interval, 1),
    ok =
    application:set_env(os_mon, system_memory_high_watermark, 0.8),
    ok =
    application:set_env(os_mon, process_memory_high_watermark,0.05),
    ok = application:set_env(os_mon, memsup_helper_timeout, 30),
    ok = application:set_env(os_mon, memsup_system_only, false),

    ok.

unavailable(suite) ->
    [];
unavailable(doc) ->
    ["Test correct behaviour when service is unavailable"];
unavailable(Config) when is_list(Config) ->

    %% Close memsup
    ok = application:set_env(os_mon, start_memsup, false),
    ok = supervisor:terminate_child(os_mon_sup, memsup),

    %% Make sure all API functions return their dummy values
    {0,0,{_Pid,0}} = memsup:get_memory_data(),
    ok = application:set_env(os_mon, memsup_system_only, true),
    {0,0,undefined} = memsup:get_memory_data(),
    ok = application:set_env(os_mon, memsup_system_only, false),
    [] = memsup:get_system_memory_data(),
    0  = memsup:get_os_wordsize(),
    60000 = memsup:get_check_interval(),
    ok = memsup:set_check_interval(2),
    5 = memsup:get_procmem_high_watermark(),
    ok = memsup:set_procmem_high_watermark(0.10),
    80 = memsup:get_sysmem_high_watermark(),
    ok = memsup:set_sysmem_high_watermark(0.90),
    30 = memsup:get_helper_timeout(),
    ok = memsup:set_helper_timeout(35),

    %% Start memsup again,
    ok = application:set_env(os_mon, start_memsup, true),
    {ok, _Child} = supervisor:restart_child(os_mon_sup, memsup),

    ok.

timeout(suite) ->
    [];
timeout(doc) ->
    ["Test stability of memsup when data collection times out"];
timeout(Config) when is_list(Config) ->

    %% Set a long memory check interval and memsup_helper timeout,
    %% we will force memory checks instead and fake timeouts
    ok = memsup:set_check_interval(60),
    ok = memsup:set_helper_timeout(3600),

    %% Provoke a timeout during memory collection
    memsup ! time_to_collect,
    memsup ! reg_collection_timeout,

    %% Not much we can check though, except that memsup is still running
    {_,_,_} = memsup:get_memory_data(),

    %% Provoke a timeout during extensive memory collection
    %% We fake a gen_server:call/2 to be able to send a timeout message
    %% while the request is being handled

    %% Linux should be handled the same way as solaris.

    %    TimeoutMsg = case ?t:os_type() of
    %		     {unix, sunos} -> ext_collection_timeout;
    %		     {unix, linux} -> reg_collection_timeout
    %		 end,

    TimeoutMsg = ext_collection_timeout,

    Pid = whereis(memsup),
    Mref = erlang:monitor(process, Pid),
    Pid ! {'$gen_call', {self(), Mref}, get_system_memory_data},
    Pid ! TimeoutMsg,
    receive
        {Mref, []} ->
            erlang:demonitor(Mref),
            ok;
        {Mref, Res} ->
            erlang:demonitor(Mref),
            ct:fail({unexpected_result, Res});
        {'DOWN', Mref, _, _, _} ->
            ct:fail(no_result)
    end,

    %% Reset memory check interval and memsup_helper timeout
    ok = memsup:set_check_interval(1),
    ok = memsup:set_helper_timeout(30),
    memsup ! time_to_collect,

    [_|_] = memsup:get_system_memory_data(),

    ok.

port(suite) ->
    [];
port(doc) ->
    ["Test that memsup handles a terminating port program"];
port(Config) when is_list(Config) ->
    Str = os:cmd("ps -e | grep '[m]emsup'"),
    case io_lib:fread("~s", Str) of
        {ok, [Pid], _Rest} ->

            %% Monitor memsup
            MonRef = erlang:monitor(process, memsup),
            {Total1,_Alloc1,_Worst1} = memsup:get_memory_data(),
            true = Total1>0,

            %% Kill the port program
            case os:cmd("kill -9 " ++ Pid) of
                [] ->

                    %% memsup should now terminate
                    receive
                        {'DOWN', MonRef, _, _, {port_died, _Reason}} ->
                            ok;
                        {'DOWN', MonRef, _, _, Reason} ->
                            ct:fail({unexpected_exit_reason, Reason})
                    after
                        3000 ->
                            ct:fail(still_alive)
                    end,

                    %% Give os_mon_sup time to restart memsup
                    ct:sleep({seconds,3}),
                    {Total2,_Alloc2,_Worst2} =
                    memsup:get_memory_data(),
                    true = Total2>0,

                    ok;

                Line ->
                    erlang:demonitor(MonRef),
                    {skip, {not_killed, Line}}
            end;
        _ ->
            {skip, {os_pid_not_found, Str}}
    end.

otp_5910(suite) ->
    [];
otp_5910(doc) ->
    ["Test that alarms are cleared and not set twice"];
otp_5910(Config) when is_list(Config) ->
    Alarms =
    [system_memory_high_watermark, process_memory_high_watermark],

    %% Make sure memsup sets both alarms
    ok = application:set_env(os_mon, memory_check_interval, 60),
    ok = memsup:set_check_interval(60),
    SysThreshold = (memsup:get_sysmem_high_watermark()/100),
    ProcThreshold = (memsup:get_procmem_high_watermark()/100),

    MemData = memsup:get_memory_data(),

    io:format("otp_5910: memsup:get_memory_data() = ~p~n", [MemData]),
    {Total, Alloc, {_Pid, _Bytes}} = MemData,
    Pid = spawn_opt(fun() ->
                            receive
                                die -> ok
                            end
                    end, [{min_heap_size, 1000}]),
    %% Create a process guaranteed to live, be constant and
    %% break memsup process limit
    {memory, Bytes} = erlang:process_info(Pid,memory),
    SysUsage = Alloc/Total,
    ProcUsage = Bytes/Total,

    if
        SysUsage>SysThreshold ->
            ok;
        SysUsage=<SysThreshold ->
            ok = application:set_env(os_mon,
                                     sys_mem_high_watermark,
                                     0.5 * SysUsage),
            ok = memsup:set_sysmem_high_watermark(0.5 * SysUsage)
    end,
    if
        ProcUsage>ProcThreshold ->
            ok;
        ProcUsage=<ProcThreshold ->
            ok = application:set_env(os_mon,
                                     proc_mem_high_watermark,
                                     0.5 * ProcUsage),
            ok = memsup:set_procmem_high_watermark(0.5 *ProcUsage)
    end,
    ok = force_collection(),
    ct:sleep({seconds,1}),
    lists:foreach(fun(AlarmId) ->
                          case alarm_set(AlarmId) of
                              {true, _} -> ok;
                              false ->
                                  ct:fail({alarm_not_set, AlarmId})
                          end
                  end,
                  Alarms),

    %% Kill guaranteed process...
    Pid ! die,
    %% Kill memsup
    exit(whereis(memsup), faked_memsup_crash),
    %% Wait a little to make sure memsup has been restarted,
    %% then make sure the alarms are set once, but not twice
    ct:sleep({seconds,1}),
    MemUsage = memsup:get_memory_data(),
    SetAlarms = alarm_handler:get_alarms(),
    case lists:foldl(fun(system_memory_high_watermark, {S, P}) ->
                             {S+1, P};
                        (process_memory_high_watermark, {S, P}) ->
                             {S, P+1};
                        (_AlarmId, Acc0) ->
                             Acc0
                     end,
                     {0, 0},
                     SetAlarms) of
        {0, 0} ->
            ok;
        _ ->
            ct:fail({bad_number_of_alarms, SetAlarms, MemUsage})
    end,

    %% Stop OS_Mon and make sure all memsup alarms are cleared
    ok = application:stop(os_mon),
    ct:sleep({seconds,1}),
    lists:foreach(fun(AlarmId) ->
                          case alarm_set(AlarmId) of
                              false -> ok;
                              {true, _} ->
                                  ct:fail({alarm_is_set, AlarmId})
                          end
                  end,
                  Alarms),

    %% Reset configuration and restart OS_Mon
    ok = application:set_env(os_mon,memory_check_interval,1),
    ok = application:set_env(os_mon,sys_mem_high_watermark,0.8),
    ok = application:set_env(os_mon,proc_mem_high_watermark,0.05),
    ok = application:start(os_mon),
    ok.

%%----------------------------------------------------------------------
%% Auxiliary
%%----------------------------------------------------------------------

force_collection() ->
    erlang:trace(whereis(memsup), true, ['receive']),
    memsup ! time_to_collect,
    TimerRef = erlang:send_after(5000, self(), timeout),
    force_collection(TimerRef).

force_collection(TimerRef) ->
    receive
        {trace, _Pid, 'receive', {collected_sys, _Sys}} ->
            erlang:cancel_timer(TimerRef),
            erlang:trace(whereis(memsup), false, ['receive']),
            flush(),
            ok;
        {trace, _Pid, 'receive', reg_collection_timeout} ->
            erlang:cancel_timer(TimerRef),
            erlang:trace(whereis(memsup), false, ['receive']),
            flush(),
            collection_timeout;
        timout ->
            erlang:trace(whereis(memsup), false, ['receive']),
            flush(),
            timeout;
        _Msg ->
            force_collection(TimerRef)
    end.

flush() ->
    receive
        {trace, _, _, _} ->
            flush();
        timeout ->
            flush()
    after 0 ->
              ok
    end.