Hey Dmitry, this is not possible if I'm understanding you correctly.
A task chain is executed by a single task thread and hence it is not possible to continue processing before the record "leaves" the thread, which only happens when the next task thread or the network stack consumes it. Hand over between chained tasks happens without serialization. Only data between different task threads is serialized. Depending on your use case the newly introduced async I/O feature might be worth a look (will be part of the upcoming 1.2 release): https://github.com/apache/flink/pull/2629
