Abstract: A system for synchronization of data processing in a data processing system including multiple command queues is disclosed. The disclosed data processing system includes one or more processing engines associated with one or more command queues. The use of multiple command queues supports multiple priority levels, such that commands in higher priority queues may preempt commands in lower priority queues. Data processing is synchronized by queue commands that allow a processing engine to queue commands on the command queue of any processing engine in the data processing system, including its own. Multiple data dependencies are resolved by conditional queue commands and event counters that queue a command only when all of the conditions precedent to execution of a particular data processing command are satisfied. The hardware queuing of the disclosed invention advantageously synchronizes data processing with minimal software supervision and with minimal latency.