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    <p>You may be misreading the valgrind output. Most likely, there is no (obvious) leak here as R is pretty well studied as a system. Yet R is a dynamically typed language which has of course done allocations. "Definitely lost: 120 bytes" is essentially measurement error -- see the valgrind docs.</p> <p>If you want to see a leak, create one, e.g., with a file like this:</p> <pre><code>library(Rcpp) cppFunction('int leak(int N) {double *ptr = (double*) malloc(N*sizeof(double)); \ return 0;}') leak(10000) </code></pre> <p>which reserves memory, even explicitly out of R's reach, and then exits. Here we get:</p> <pre><code>$ R -d "valgrind" -f /tmp/leak.R [...] R&gt; leak(10000) [1] 0 R&gt; ==4479== ==4479== HEAP SUMMARY: ==4479== in use at exit: 35,612,126 bytes in 15,998 blocks ==4479== total heap usage: 47,607 allocs, 31,609 frees, 176,941,927 bytes allocated ==4479== ==4479== LEAK SUMMARY: ==4479== definitely lost: 120 bytes in 2 blocks ==4479== indirectly lost: 480 bytes in 20 blocks ==4479== possibly lost: 0 bytes in 0 blocks ==4479== still reachable: 35,611,526 bytes in 15,976 blocks ==4479== suppressed: 0 bytes in 0 blocks ==4479== Rerun with --leak-check=full to see details of leaked memory ==4479== ==4479== For counts of detected and suppressed errors, rerun with: -v ==4479== Use --track-origins=yes to see where uninitialised values come from ==4479== ERROR SUMMARY: 31 errors from 10 contexts (suppressed: 2 from 2) $ </code></pre> <p>Now there is a bit more of a leak (though it is still not as easily readable as one would hope). If you add the suggested flags, it will eventually point to the <code>malloc()</code> call we made.</p> <p>Also, I have a worked example of actual leak in an earlier version of a CRAN package in one of my 'Intro to HPC with R' slide sets. If and when there is a leak, this helps. When there is none, it is harder to see through the noise.</p> <p>So in short, if you code crashes, it is probably your code's fault. Try a minimal reproducible example is the (good) standard advice.</p>
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    1. POMy R has memory leaks?
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    1. USDirk Eddelbuettel
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    1. COThanks! I found the valgrind output quite confusing. I started having doubts about leaks because just calling an Rcpp function such as: NumericMatrix myMat(int nCols, int nRows) { NumericMatrix out(nRows, nCols); return out; } is occasionally causing R to crash with segfault if I call this function iteratively in an R loop: for(ii in 1:10^6) mat <- myMat(100, 100)
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    2. COIf you can reproduce a segfault, and maybe run under `gdb`, then we can possibly improve things. Otherwise, it is near-impossible.
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      1. USDirk Eddelbuettel
    3. COYou are right, if I manage to reproduce the error I'll post it in another question. Thanks
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