I am using 4 projects together in a single workspace. Currently I am using Eclipse mars (32-bit) and JAVA 7. When I tried to change Java 7 to Java 8, I am facing Java heap size no memory issue. Is there any other configuration to be updated while upgrading from java 7 to java 8 ?
When your source code makes heavy use of generics, increased demands of heap space may be due to intrinsic complexity of the new type inference in Java 8.
Under Preferences > General you can enable [x] Show heap status to watch heap usage over time.
Finally, have a look at FAQ How do I increase the heap size available to Eclipse?