You might be aware that every application written in Java is well known for out-of-memory problems. Before we learn how to deal with the out-of-memory problems, let us define out-of-memory in Java terms and briefly understand why such problems occur. It is defined as the state of a Java machine where no additional memory can be allocated to run a process that is in progress. This results in the denial of transferring additional data into the memory, which is essential to run a process appropriately, thereby leading to a cease of the process. We recommend that you refer to the out-of-memory Wiki page at http://en.wikipedia.org/wiki/Out_of_memory if you want to know more about it.

As far as Solr is concerned, these problems are usually associated with a low heap size. We will learn how to avoid and resolve such problems in this section.

You might come across an exception that looks similar to the following one:

SEVERE: java.lang.OutOfMemoryError: Java heap space...