Azul’s C4, our Continuously Concurrent Compacting Collector is an updated generational form of the Pauseless Garbage Collector Algorithm described in 2005 at the First International Conference on Virtual Execution Environments and is one of the key technologies behind the Zing JVM.
About our C4 Garbage Collector
C4 uses a read barrier to support:
- Concurrent Compaction
- Concurrent Remapping
- Concurrent Incremental Update Tracing
Azul Systems Zing runtime has been shipping a production implementation of the C4 collector mechanism since 2010.
How C4 differentiates itself from other Garbage Collectors?
C4 supports simultaneous-generational concurrency while others use concurrent mechanisms that can be simultaneously and independently active.
C4 can perform concurrent young generation collections, even during long periods of concurrent full heap collection
C4 can sustain high allocation rates and maintain the efficiency typical to generational collectors, without sacrificing response times or reverting to stop-the-world operation.
One of the primary advantages of the C4 collector is the ability to adapt to a wide variety of use cases without the need for tuning. C4 is equally useful in web-facing/human-response-sensitive applications, in throughput-sensitive batch analytics, and in latency-sensitive applications like real-time risk analytics. C4 is also appropriate for memory configurations ranging anywhere from 512 MB to (as of this writing) 8 TB, although most production instances using Zing run in configurations supporting between 4GB and 256GB of memory.
Understanding Java GC
Azul Pauseless Garbage Collection
C4: The Continuously Concurrent Compacting Collector
