Methods and apparatus to support multiple-writer/multiple-reader concurrency for software flow/packet classification on general purpose multi-core systems. A flow table with rows mapped to respective hash buckets with multiple entry slots is implemented in memory of a host platform with multiple cores, with each bucket being associated with a version counter. Multiple writer and reader threads are run on the cores, with writers providing updates to the flow table data. In connection with inserting new key data, a determination is made to which buckets will be changed, and access rights to those buckets are acquired prior to making any changes. For example, under a flow table employing cuckoo hashing, access rights are acquired to buckets along a full cuckoo path. Once the access rights are obtained, a writer is enabled to update data in the applicable buckets to effect entry of the new key data, while other writer threads are prevented from changing any of these buckets, but may concurrently insert or modify key data in other buckets.