Assessing the Scalability of Garbage Collectors on Many Cores

In conjunction with the 23rd ACM Symposium on Operating Systems Principles (SOSP 2011)International audienceManaged Runtime Environments (MRE) are increasingly used for application servers that use large multi-core hardware. We find that the garbage collector is critical for overall performance in this setting. We explore the costs and scalability of the garbage collectors on a contemporary 48-core multiprocessor machine. We present experimental evaluation of the parallel and concurrent garbage collectors present in OpenJDK, a widely-used Java virtual machine. We show that garbage collection represents a substantial amount of an application's execution time, and does not scale well as the number of cores increases. We attempt to identify some critical scalability bottlenecks for garbage collectors