Recent evolution of 5G networks introduce new challenges for the allocation of resources for service requests. Slicing in 5G networks allows multiple users to share a common infrastructure and the chaining of Virtual Network Functions (VNF)s introduces constraints on the order in which NFs are allocated. We discuss the allocation of resources for Service Chains of VNFs in 5G Slices and in particular of distributed mutual exclusion algorithms. We explain with selected metrics that choosing an order of allocation of the resources that differs from the order in which resources are used can give better performances. We discuss experimental results of Fraysse et al. (2020) in which the authors improve the usage rate of resources by more than 20% compared to a baseline algorithm in some cases, and will discuss our own preliminary numerical results if available at the time of the presentation.