Not to say you shouldn't do this, but I worry that increasingly computing is being done in "containers" where e.g. the number of cpus is doubling every year but only a small number are available to actually be used by a given process. if availableProcessors reports 1 million, what should we do? (no need to answer...)
On Tue, Dec 1, 2015 at 1:55 AM, Erik Joelsson <erik.joels...@oracle.com> wrote: > Hello, > > The current heuristic for figuring out what to default set the -j flag to > make needs some tweaking. > > In JDK 9, it looks at the amount of memory and the number of cpus in the > system. It divides memory by 1024 to get a safe number of jobs that will > fit into memory. The lower of that number and the number of cpus is then > picked. The number is then scaled down to about 90% of the number of cpus > to leave some resources for other activities. It is also capped at 16. > > Since we now have the build using "nice" to make sure the build isn't > bogging down the system, I see no reason to do the 90% scaling anymore. > Also, the performance issues that forced us to cap at 16 have long been > fixed, and even if we don't scale well beyond 16, we do still scale. So I > propose we remove that arbitrary limitation too. > > Bug: https://bugs.openjdk.java.net/browse/JDK-8144312 > Webrev: http://cr.openjdk.java.net/~erikj/8144312/webrev.01/ > > /Erik >
