Memory Size issue is coming while we have increased a lots of Memory Fatal error: Allowed memory size of 1073741824 bytes exhausted (tried to allocate 71 bytes) in /home/public_html/includes/theme.inc on line 98
1073741824 bytes = 1GB, so that should be more than enough. I have my development machine set to memory_limit = 256M, which is already pretty much, and I never run into exhausted memory problems.

Your error is probably caused by a mistake or some very inefficient logic in your code. There are a couple of things you can do to find the problem, like:


Switch to a standard theme, to narrow down if the theme is causing the problem.
Disable modules you added recently, one by one, to see which module is causing the problem.
Search for loops in your code that may keep running indefinitely.
Use a step debugger (like Xdebug) to find the point in code where the problem is caused. (Xdebug takes some setting up, but installing it is well worth your time.)
Use a profiler (like XHprof) to see where your memory is going. (Installing and learning XHprof takes time, but if the other methods don't work for you, it can probably answer your question.)