Hello Monks,

I do not understand the behavior of threads, and prevent them coming into LOCK state.

I did two tests, in which the only difference is that one has an inner loop. I wanted to understand why the test with the Inner Loop (Test2) put the CPU USER state at 100% and without this inner loop, the threads are being LOCKED (see column of LCK PRSTAT).

Test1: 
#!/opt/coolstack/bin/perl

use strict;

use threads ('yield',
                 'stack_size' => 64*4096,
                 'exit' => 'threads_only',
                 'stringify');


my $nloaders = 64;
#---------------------------------------------------------------

my @thrs_loaders;


for(1..$nloaders){
  print "START  LOAD $_ \n";
  my ($thr) =  threads->create(\&load, $_);
  push @thrs_loaders ,$thr;
}


$_->join for @thrs_loaders;

print "STOP: " . localtime() . "\n";
exit;

#---------------------------------------------------------------------
+---------
sub load{
  my $id = shift;
  my $tmp;


  for(1..7235617){
    int( rand (10));
  }
  print "$id>LOAD EXIT\n";
}

[download]
PRSTAT for Test1: 
   PID USERNAME USR SYS TRP TFL DFL LCK SLP LAT VCX ICX SCL SIG PROCESS/LWPID
 19883 mgarcia  100 0.0 0.0 0.0 0.0 0.0 0.0 0.0   0  24   3   0 perl/43
 19883 mgarcia  100 0.0 0.0 0.0 0.0 0.0 0.0 0.0   0  28   2   0 perl/34
 19883 mgarcia  100 0.0 0.0 0.0 0.0 0.0 0.0 0.0   0  26   3   0 perl/63
 19883 mgarcia  100 0.0 0.0 0.0 0.0 0.0 0.0 0.0   0  26   3   0 perl/62
 19883 mgarcia  100 0.0 0.0 0.0 0.0 0.0 0.0 0.0   0  26   3   0 perl/61
 19883 mgarcia  100 0.0 0.0 0.0 0.0 0.0 0.0 0.0   0  23   3   0 perl/51
 19883 mgarcia  100 0.0 0.0 0.0 0.0 0.0 0.0 0.0   0  29   3   0 perl/58
 19883 mgarcia  100 0.0 0.0 0.0 0.0 0.0 0.0 0.0   0  35   3   0 perl/57
 19883 mgarcia  100 0.0 0.0 0.0 0.0 0.0 0.0 0.0   0  35   3   0 perl/56
 19883 mgarcia  100 0.0 0.0 0.0 0.0 0.0 0.0 0.0   0  35   3   0 perl/45
 19883 mgarcia  100 0.0 0.0 0.0 0.0 0.0 0.0 0.0   0  33   2   0 perl/31
 19883 mgarcia  100 0.0 0.0 0.0 0.0 0.0 0.0 0.0   0  35   2   0 perl/19
 19883 mgarcia  100 0.0 0.0 0.0 0.0 0.0 0.0 0.0   0  37   3   0 perl/50
 19883 mgarcia  100 0.0 0.0 0.0 0.0 0.0 0.0 0.0   0  36   3   0 perl/41
 19883 mgarcia  100 0.0 0.0 0.0 0.0 0.0 0.0 0.0   0  37   2   0 perl/36
Test2: 
#---------------------------------------------------------------------
+---------
sub load{
  my $id = shift;
  my $tmp;


  for(1..7235617){
    for(1..100000){    
       $tmp = $_;
    }
    int( rand (10));
  }
  print "$id>LOAD EXIT\n";
}

[download]
PRSTAT for Test2: 
   PID USERNAME USR SYS TRP TFL DFL LCK SLP LAT VCX ICX SCL SIG PROCESS/LWPID
 19894 mgarcia   60 0.1 0.0 0.0 0.0  40 0.0 0.0  22  20  36   0 perl/19
 19894 mgarcia   58 0.1 0.0 0.0 0.0  42 0.0 0.0  19  25  48   0 perl/56
 19894 mgarcia   57 0.0 0.0 0.0 0.0  43 0.0 0.0  21  20  41   0 perl/32
 19894 mgarcia   56 0.1 0.0 0.0 0.0  44 0.0 0.0  19  18  31   0 perl/23
 19894 mgarcia   50 0.1 0.0 0.0 0.0  50 0.0 0.0  19  20  52   0 perl/25
 19894 mgarcia   50 0.1 0.0 0.0 0.0  50 0.0 0.0  18  20  54   0 perl/33
 19894 mgarcia   34 0.1 0.0 0.0 0.0  66 0.0 0.0  17  12  47   0 perl/34
 19894 mgarcia   32 0.1 0.0 0.0 0.0  68 0.0 0.0  19  13  53   0 perl/10
 19894 mgarcia   30 0.1 0.0 0.0 0.0  70 0.0 0.0  22  14  43   0 perl/15
 19894 mgarcia   25 0.0 0.0 0.0 0.0  75 0.0 0.0  21  14  36   0 perl/65
 19894 mgarcia   23 0.1 0.0 0.0 0.0  77 0.0 0.0  20  12  42   0 perl/4
 19894 mgarcia   22 0.1 0.0 0.0 0.0  77 0.0 0.0  21  10  47   0 perl/9
 19894 mgarcia   18 0.1 0.0 0.0 0.0  81 0.0 0.0  24  12  63   0 perl/22
 19894 mgarcia   18 0.1 0.0 0.0 0.0  82 0.0 0.0  20  11  51   0 perl/55

In reply to Solaris + UltraSparc T2 + Threads: Avoid LCK's by gulden

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