Parallel calculations: Difference between revisions
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→{{header|Perl 6}}: Expand output to more fully show what is going on, style twiddles
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Takes the list of numbers and converts them to a <tt>HyperSeq</tt> that is stored in a raw variable. Any <tt>HyperSeq</tt> overloads <tt>map</tt> and <tt>grep</tt> to convert and pick values in worker threads. The runtime will pick the number of OS-level threads and assign worker threads to them while avoiding stalling in any part of the program. A <tt>HyperSeq</tt> is lazy, so the computation of values will happen in chunks as they are requested.
The hyper (and race) method can take two parameters that will tweak how the parallelization occurs: :degree and :batch. :degree is the number of worker threads to allocate to the job. By default it is set to the number of physical cores available. If you have a hyper threading processor, and the tasks are not cpu bound, it may be useful to raise that number but it is a reasonable default. :degree is how many sub-tasks are parcelled out at a time to each worker thread. Default is 64. For small numbers of cpu intensive tasks a lower number will likely be better, but too low may make the dispatch overhead cancel out the benefit of threading. Conversely, too high will over-burden some threads and starve others. Over long
On my system, under the load I was running, I found a batch size of 3 to be optimal for this task. May be different for different systems and different loads.
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278352769033314050117, 281398154745309057242, 292057004737291582187;
my
say my $gmf = {}.append(factories»[0] »=>« @nums).max: {+.key};▼
printf "%21d factors: %s\n", |$_ for @nums Z @factories;
say "\nGreatest minimum factor: ", $gmf.key;
say "from: { $gmf.value }\n";
say 'Run time: ', now - INIT now;
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}</lang>
{{out|Typical output}}
<pre>
70251412046988563035 factors: 5 43 349 936248577956801
Run time: 0.2893774</pre>▼
71774104902986066597 factors: 736717 97424255043641
83448083465633593921 factors: 736717 113270202079813
84209429893632345702 factors: 2 3 3 3 41 107880821 352564733
87001033462961102237 factors: 736717 118092881612561
87762379890959854011 factors: 3 3 3 3 331 3273372119315201
89538854889623608177 factors: 736717 121537652707381
98421229882942378967 factors: 736717 133594351539251
259826672618677756753 factors: 7 37118096088382536679
262872058330672763871 factors: 3 47 1864340839224629531
267440136898665274575 factors: 3 5 5 71 50223499887073291
278352769033314050117 factors: 7 39764681290473435731
281398154745309057242 factors: 2 809 28571 46061 132155099
292057004737291582187 factors: 7 151 373 2339 111323 2844911
Greatest minimum factor: 736717
from: 64921987050997300559 71774104902986066597 83448083465633593921 87001033462961102237 89538854889623608177 98421229882942378967
Beside <tt>HyperSeq</tt> and its (allowed to be) out-of-order equivalent <tt>RaceSeq</tt>, [[Rakudo]] supports primitive threads, locks and highlevel promises. Using channels and supplies values can be move thread-safely from one thread to another. A react-block can be used as a central hub for message passing.
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