> Set -Xms to "I know it wants at least this much". > Set -Xmx to significantly, but not wildly, more.
no, always set them to the same no matter what. I like increments of 1024M so I would start at 2048M and work up to 8gb and see how it performs. Having a test script that forks to how many users at one given point you are expecting helps a lot to see what is going to happen in the real world. On Thu, Mar 9, 2023 at 8:39 AM Mark H. Wood <mw...@iupui.edu> wrote: > On Thu, Mar 09, 2023 at 01:56:11PM +0100, Jan Høydahl wrote: > > It's a waste to set heap to 30g if your use of Solr only requires 6g to > function. That is 24G memory not being used for index caching, and it will > may, depending on chose GC, cause bigger/longer GC events as more garbage > piles up before collection. > > > > You have to measure and experiment to find your heap sweetspot. > > Very sensible. > > It seems to me that there are two situations: > > 1 I don't know how much heap is right for my appllication: > Set -Xms to "I know it wants at least this much". > Set -Xmx to significantly, but not wildly, more. > Monitor performance. > If better than previous settings, set -Xms to -Xmx and increase -Xmx. > Repeat until performance is worse or the heap never expands beyond > -Xms. If it got worse, then back off. > You are now in the second situation. > > 2 I know how much heap is right for my application: > Set -Xms = -Xmx = that much. > Continue to monitor, because workloads can change. > > Comments? > > -- > Mark H. Wood > Lead Technology Analyst > > University Library > Indiana University - Purdue University Indianapolis > 755 W. Michigan Street > Indianapolis, IN 46202 > 317-274-0749 > www.ulib.iupui.edu >
