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POAsynchronous evaluation in Mathematica
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copied!<p>Sometimes when I'm writing experimental code in Mathematica, I'm wary as to whether I should evaluate it or not because it may end up bringing my system to it's knees.</p> <p>As a contrived example if you try running the following snippet of code on a 64-bit machine, it will most likely cause your system to grind to a complete halt after it eats up all your memory.</p> <pre><code>junk = Table[{x, x}, {10^9}]; (* nom nom nom memory. Please don't run this. *) </code></pre> <p>Sure, you can just throw <code>MemoryConstrained</code> onto it and hope for the best, but sometimes you don't want it blocking any further input. To that end, the way I thought it might be best to achieve a middle ground was to perform the evaluation in a separate kernel.</p> <p>That was decently easy enough to do:</p> <pre><code>ClearAll[GetAvailableKernel]; GetAvailableKernel[] := Block[{i, kernels}, kernels = Kernels[]; If[Length@kernels != 0, For[i = 1, i <= Length@kernels, i++, If[kernels[[i, 1, 2]] > 0, Return@kernels[[i]]] ] ]; LaunchKernels[1]] ClearAll[SafeEvaluate]; SetAttributes[SafeEvaluate, HoldFirst]; Options[SafeEvaluate] = {"EvaluationKernel" -> Null, "ConstrainMemory" -> True, "MaxMemory" -> 2 1024^3}; SafeEvaluate[expr_, OptionsPattern[]] := Block[{evalkernel, result}, If[OptionValue["EvaluationKernel"] != Null, evalkernel = OptionValue["EvaluationKernel"], evalkernel = GetAvailableKernel[] ]; result = If[OptionValue["ConstrainMemory"], With[{memory = OptionValue["MaxMemory"]}, ParallelEvaluate[MemoryConstrained[expr, memory], evalkernel]], ParallelEvaluate[expr, evalkernel]]; result] </code></pre> <p>Then you could just go ahead and do something along the lines of:</p> <pre><code>SafeEvaluate[Table[{x, x}, {1024^3}]] </code></pre> <p>And Mathematica would gracefully return <code>$Aborted</code> telling you it ran out of memory. By evaluating in a separate kernel, we can sandbox code into it's own parallel kernel. If something goes wrong, then our main kernel isn't affected.</p> <hr> <p>This brings me to my main point: <strong>How can I achieve asynchronous evaluation within Mathematica?</strong></p> <p>What I have right now works, but it completely blocks any further user input. I can't just set, forget, and check later.</p> <p>Any thoughts?</p>

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