On 11/10/2016 3:20 PM, Chetas Joshi wrote: > I have a SolrCloud (Solr 5.5.0) of 50 nodes. The JVM heap memory usage > of my solr shards is never more than 50% of the total heap. However, > the hosts on which my solr shards are deployed often run into 99% swap > space issue. This causes the solr shards go down. Why solr shards are > so sensitive to the swap space usage? The JVM heap is more than enough > so the shards should never require the swap space. What could be the > reason? Where can find the reason why the solr shards go down. I don't > see anything on the solr logs.
If the machine that Solr is installed on is using swap, that means you're having serious problems, and your performance will be TERRIBLE. This kind of problem cannot be caused by Solr if it is properly configured for the machine it's running on. Solr is a Java program. That means its memory usage is limited to the Java heap, plus a little bit for Java itself, and absolutely cannot go any higher. If the Java heap is set too large, then the operating system might utilize swap to meet Java's memory demands. The solution is to set your Java heap to a value that's significantly smaller than the amount of available physical memory. Setting the heap to a value that's close to (or more than) the amount of physical memory, is a recipe for very bad performance. You need to also limit the memory usage of other software installed on the machine, or you might run into a situation where swap is required that is not Solr's fault. Thanks, Shawn
