Did you ever analyze the generated heapdump file? With this option it generates a copy of the Java memory to a file when it runs out of memory. So you can analyze what is the root cause and if there is a memory leak.
See also:
How to find the cause of a OutOfMemoryError in OH2?
Ahhh I see you did in How to find the cause of a OutOfMemoryError in OH2? - #27 by NCO . Looks like it is caused by the sitemap events.