cores=0 now uses all but one core, rather than all cores

Author: kbroman

DESCRIPTION

@@ -1,6 +1,6 @@
 Package: qtl2
-Version: 0.43-4
-Date: 2026-06-16
+Version: 0.43-5
+Date: 2026-06-27
 Title: Quantitative Trait Locus Mapping in Experimental Crosses
 Description: Provides a set of tools to perform quantitative
     trait locus (QTL) analysis in experimental crosses. It is a

NEWS.md

@@ -1,4 +1,4 @@
-## qtl2 0.43-4 (2026-06-16)
+## qtl2 0.43-5 (2026-06-27)
 
 ### New features
 
@@ -13,6 +13,10 @@
 - Potential speed-up of `scan1()` and `scan1perm()`: the eigen library
   has implemented least squares regression with multivariate outcomes.
 
+- For parallel computing, use of `cores=0` argument now results in all
+  but one core (`parallel::detectCores()-1`) rather than **all**
+  cores.
+
 
 ## qtl2 0.42 (2026-06-08)
 

R/cluster_util.R

@@ -22,7 +22,7 @@ setup_cluster <-
     if(is_cluster(cores)) return(cores)
 
     if(is.null(cores) || is.na(cores)) cores <- 1
-    if(cores==0) cores <- parallel::detectCores() # if 0, detect cores
+    if(cores==0) cores <- max(1, parallel::detectCores()-1, na.rm=TRUE) # if 0, detect cores
     if(is.na(cores)) cores <- 1
 
     if(cores > 1 && Sys.info()[1] == "Windows") { # windows doesn't support mclapply