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
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