Dear parallel users and developers, I might have encountered a bug in the function 'mclapply' of package 'parallel'. I construct a matrix using the same input data and code with a single difference: Once I use mclapply and the other time lapply. Shockingly the result is NOT the same. To evaluate please unpack the attached archive and execute Rscript mclapply_test.R I put the two simple functions I wrote inside the R script and the serialized input matrix. My function is once executed using mclapply and the other time lapply internally. - There's an argument lapply.funk, one can set to mclapply. The results are checked for identity with a striking FALSE. Any hints on my misuse and or misunderstanding of mclapply or verification of a true bug will be much appreciated. Kind regards!
possible bug in function 'mclapply' of package parallel
2 messages · Asis Hallab, R. Michael Weylandt
Mailing list ate the attachment. Can you send it plain text (if short) or post it somewhere online? Michael
On Dec 13, 2012, at 1:54 AM, Asis Hallab <asis.hallab at gmail.com> wrote:
Dear parallel users and developers, I might have encountered a bug in the function 'mclapply' of package 'parallel'. I construct a matrix using the same input data and code with a single difference: Once I use mclapply and the other time lapply. Shockingly the result is NOT the same. To evaluate please unpack the attached archive and execute Rscript mclapply_test.R I put the two simple functions I wrote inside the R script and the serialized input matrix. My function is once executed using mclapply and the other time lapply internally. - There's an argument lapply.funk, one can set to mclapply. The results are checked for identity with a striking FALSE. Any hints on my misuse and or misunderstanding of mclapply or verification of a true bug will be much appreciated. Kind regards!
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