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<p class="MsoNormal"><span style="color:#1F497D">Greetings and Salutations,<o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D">The answer is yes, multiple processes can concurrently modify different parts of the object. So, the object is not “locked.”<o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D">In this case, it’s important to note the scope of the object being “shared” and not “private.”<o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D">Also, the object is not being used in any computations that could introduce a race condition.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D">To confirm, here is a simple test using cores = 1:5 and a matrix of 100 x 100 dimensions:<o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D">Unit: milliseconds<o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D">expr min lq mean median uq max neval<o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D">reg 149.16828 150.57064 151.50028 151.14911 151.77306 167.89586 100<o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D">omp_1core 148.61683 150.38602 150.97419 150.92021 151.42784 153.87262 100<o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D">omp_2core 76.87057 77.67058 78.72599 78.07599 78.75143 88.49076 100<o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D">omp_3core 52.86078 53.41599 55.48897 53.81420 56.09687 66.68860 100<o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D">omp_4core 40.09745 42.64505 46.52619 44.09979 49.99153 63.37927 100<o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D">omp_5core 39.23680 44.04410 46.22926 45.22581 48.45514 51.05932 100<o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D">> all.equal(updateImplicitX(test,test,test,test,5),updateImplicitX_p(test,test,test,test,5,3))<o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D">[1] TRUE<o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D">So, there is ~2x – 3.4x speed up vs. the non-parallel version.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D">Parallel version using my suggestions and benchmarking…<o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D"><br>
<a href="https://gist.github.com/coatless/5c4f95c69f7a1b61b2a5">https://gist.github.com/coatless/5c4f95c69f7a1b61b2a5</a><o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D">Sincerely,<o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D">JJB</span><o:p></o:p></p>
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