The Impact of Software Resource Allocation on Consolidated n-Tier Applications

Consolidating several under-utilized user applications together to achieve higher utilization of hardware resources is important for cloud vendors to reduce cost and maximize profit. In this paper, we study the impact of tuning software resources (e.g., server thread pool size or connection pool size) on n-tier web application performance in a consolidated cloud environment. By measuring CPU utilizations and performance of two consolidated n-tier web application benchmark systems running RUBBoS, we found significant differences depending on the amount of soft resources allocated. When the two systems have different soft resource allocations and are fully utilized, the application with more software resources may steal up to 8% CPU from the co-resident application. Further analysis shows that the CPU stealing is due to more threads being scheduled for the system with higher software resources. By limiting the number of runnable active threads for the consolidated VMs, we were able to mitigate the performance interference. More generally, our results show that careful software resource allocation is a significant factor when deploying and tuning n-tier application performance in clouds.