Re: [Bug-apl] Potential problem with T∆

[Christian Robert]

Nope, without "Parallel" it still core dump.

Xtian.

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                     Welcome to GNU APL version 1.4 / 9328

                Copyright (C) 2008-2014  Dr. Jürgen Sauermann
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                This program comes with ABSOLUTELY NO WARRANTY;
                  for details run: /usr/local/bin/apl --gpl.

     This program is free software, and you are welcome to redistribute it
         according to the GNU Public License (GPL) version 3 or later.

      ⎕syl
 SI depth limit          (0 = no limit)                    0
 number of values limit  (0 = no limit)                    0
 total ravel bytes limit (0 = no limit)                    0
 current SI depth                                          1
 current number of values                                 29
 current total ravel bytes                             12288
 max. rank for APL values                                  8
 min. ⎕PW                                                 30
 max. ⎕PW                                               1000
 min. ⎕PP                                                  1
 max. ⎕PP                                                 16
 log10(max. ⎕CT)                                          ¯9
 max. input line length                                 2000
 max. symbol count                                     65536
 max. shared variable name length                         64
 max. length of filenames (paths)                       4096
 max. # of shared variables (obsolete)                    64
 max. number of APs                                       16
 max. operators per statement                             16
 largest integer                         9200000000000000000
 smallest (negative) integer            ¯9200000000000000000
 largest numeric exponent                                308
 max. shared variable size (bytes)                     65000
 CORE_COUNT_WANTED (per ./configure)                       0
 cores available                                           1
 cores used                                                1
 print length limit (0 = no limit)                         0
 max. prefix length                                       60
      )load Util
SAVED 2015-03-17 -3:23:11 (GMT-4)
      T∆Time←⍳1000
      Time 'a←⍳1000000'
Time[4] SYLGet
Time[5] SYLSet
Time[9] →⍬
Time[10] 1
Time[12] 0
Time[13] 1
Time[14] 1
Time[15] 1
Time[19] 1
Time[20] 17 12 51 22 301
Segmentation fault (core dumped)


On 2015-03-17 06:42, Juergen Sauermann wrote:
> Hi Xtian,
>
> it looks like you are using the multi-core feature of GNU APL.
> As *README-8-parallel* says: *Parallel execution is currently experimental*.
>
> I have seen core dumps like those earlier when multi-core was enabled, but have 
> not found the reason.
> I suspect a bug in the thread synchronization, but I am not sure, The code at 
> the point where the crash below occurs
> looks rather clean, thats why I believe that some other thread is involved, 
> corrupting the memory of the other
> threads. If you find a bug in the *Parallel.hh* / *Parallel.**cc* area then 
> please let me know.
>
> You can also use the *workspaces/ScalarBenchmark.apl* workspace which uses a 
> more precise timing
> measurement based on the CPU cycle counter. It also crashes at times, but not 
> so often.
>
> /// Jürgen
>
>
> On 03/17/2015 02:33 AM, Christian Robert wrote:
> > )load Util
> > SAVED 2015-03-17 -3:23:11 (GMT-4)
> >       ∇Time[⎕]∇
> >     ∇
> > [0]   z←ncpu Time what;⎕io;start;stop;old_cpu;max_cpu;SYLGet;SYLSet
> > [1]  ⍝
> > [2]  ⍝ Define 2 utility functions
> > [3]  ⍝
> > [4]   z←⎕FX 'Z←SYLGet what;⎕io;index' '⎕io←1' 'index←((⊂ 
> > what)≡¨⎕SYL[;1])/⍳↑⍴⎕SYL' 'Z←⎕SYL[index;2]'
> > [5]   z←⎕FX 'Z←val SYLSet what;⎕io;index' '⎕io←1' 'index←((⊂ 
> > what)≡¨⎕SYL[;1])/⍳↑⍴⎕SYL' 'Z←⎕SYL[index;2]←val'
> > [6]  ⍝
> > [7]  ⍝ Monadic or Diadic call ?
> > [8]  ⍝
> > [9]   →(2=⎕NC 'ncpu')/already_set
> > [10]    ncpu←1 ⍝ Set the default
> > [11] already_set:
> > [12]  ⎕io←0
> > [13]  old_cpu ← SYLGet 'cores used'
> > [14]  max_cpu ← SYLGet 'cores available'
> > [15]  ncpu ← ncpu ⌊ max_cpu  ⍝ No more than available ...
> > [16] ⍝
> > [17] ⍝ Execute ...
> > [18] ⍝
> > [19]  z←ncpu SYLSet 'cores used'
> > [20]  start ← ¯5↑⎕ts
> > [21]  ⍎what
> > [22]  stop  ← ¯5↑⎕ts
> > [23]  z←old_cpu SYLSet 'cores used'
> > [24] ⍝
> > [25] ⍝ Compute execution time
> > [26] ⍝
> > [27]  →(stop[0]=start[0])/ok    ⍝ same day
> > [28]    stop[0]←stop[0]+1       ⍝ day changed
> > [29] ok:
> > [30]  start ← 32 24 60 60 1000 ⊥ start
> > [31]  stop  ← 32 24 60 60 1000 ⊥ stop
> > [32]  z←(⍕(stop-start)÷1000),' seconds at num core = ',(⍕ncpu),' of ', ⍕max_cpu
> >     ∇
> >       Fntb 'Time'
> >  z←ncpu Time what;⎕io;start;stop;old_cpu;max_cpu;SYLGet;SYLSet
> >  ⍝
> >  ⍝ Define 2 utility functions
> >  ⍝
> >  z←⎕FX 'Z←SYLGet what;⎕io;index' '⎕io←1' 'index←((⊂ what)≡¨⎕SYL[;1])/⍳↑⍴⎕SYL' 
> > 'Z←⎕SYL[index;2]'
> >  z←⎕FX 'Z←val SYLSet what;⎕io;index' '⎕io←1' 'index←((⊂ 
> > what)≡¨⎕SYL[;1])/⍳↑⍴⎕SYL' 'Z←⎕SYL[index;2]←val'
> >  ⍝
> >  ⍝ Monadic or Diadic call ?
> >  ⍝
> >  →(2=⎕NC 'ncpu')/already_set
> >    ncpu←1 ⍝ Set the default
> >  already_set:
> >  ⎕io←0
> >  old_cpu ← SYLGet 'cores used'
> >  max_cpu ← SYLGet 'cores available'
> >  ncpu ← ncpu ⌊ max_cpu  ⍝ No more than available ...
> >  ⍝
> >  ⍝ Execute ...
> >  ⍝
> >  z←ncpu SYLSet 'cores used'
> >  start ← ¯5↑⎕ts
> >  ⍎what
> >  stop  ← ¯5↑⎕ts
> >  z←old_cpu SYLSet 'cores used'
> >  ⍝
> >  ⍝ Compute execution time
> >  ⍝
> >  →(stop[0]=start[0])/ok    ⍝ same day
> >    stop[0]←stop[0]+1       ⍝ day changed
> >  ok:
> >  start ← 32 24 60 60 1000 ⊥ start
> >  stop  ← 32 24 60 60 1000 ⊥ stop
> >  z←(⍕(stop-start)÷1000),' seconds at num core = ',(⍕ncpu),' of ', ⍕max_cpu
> >
> >
> >
> >       T∆Time ← ⍳1000
> >       Time 'a←⍳1000000'
> > Time[4] SYLGet
> > Time[5] SYLSet
> > Time[9] →⍬
> > Time[10] 1
> > Time[12] 0
> > Time[13] 1
> > Time[14] 6
> > Time[15] 1
> > Time[19] 1
> > Time[20] 16 21 28 46 188
> > Segmentation fault (core dumped)