read.bismark doesn't finish with new R.

[desmodus1984]

Hello,

I use RStudio, and I told that the best is to have the latest up-to-date version of the software, so I updated and installed the latest version of RStudio 2024 B 735 with R 4.4.1.
I am trying to reanalyze a dataset of 44 samples with dmrseq which uses read.bismark to create the dataset. I then tried reading some samples for making a set with files created with methyldackel; they loaded relatively fast in previous version, but now, it's been almost 5 hours (2 days now), and the log is frozen in the "Parsing files and constructing 'M' and 'Cov' matrices ..." step.

[read.bismark] Parsing files and constructing valid loci ...
Done in 62.1 secs
[read.bismark] Parsing files and constructing 'M' and 'Cov' matrices ...

I am working in a workstation with huge memory, 400GB. Since I was reading a small dataset 9 files, I realized that that is not my full dataset- thus, I I tried loading the full 44 samples.
Almost 5 hours (2 days now) and read.bismark step has not finished.
With the aim of increasing speed I set the parameter nThread to 8L, and 10L, for 9 samples and full 44 samples dataset, respectively.

Do you have any idea why this step is taking so much time to finish now with the new R?
I have to tell that with the new R I had to install dmrseq again- which installed all the required software again, so I don't know what might be slowing it down so much.

Thank;

Juan Pablo

[PeteHaitch]

I can't think of anything off-hand that has changed in the last 5-7 years with read.bismark().

How many methylation loci are in these files?

In general, I suggest sticking with nThread = 1, particularly if you are using other parallelisation via the BPPARAM parameter.
I would test how long it takes to read 1 file, then 2, then 4, etc. to narrow down when it's breaking down on your system.