1. A method for performing garbage collection, comprising: obtaining a first reference bitmap comprising a block address and a plurality of mark bits; obtaining a first reference; identifying a mark bit of the plurality of mark bits based on the first reference; comparing an address associated with the mark bit and the first reference to generate a comparison; selecting an existing word from a global bit map based on the block address and the comparison; calculating a new word based on the plurality of mark bits and the existing word; replacing the existing word in the global bit map with the new word; reclaiming a block of memory for reuse based on the global bit map after replacing the existing word; performing a bitwise negation operation on the existing word to generate a negated existing word; performing a bitwise AND operation on the negated existing word and the plurality of mark bits to generate a result; and identifying a second reference based on the result, wherein the second reference is reachable.