Cold start delays are a main pain point for today's FaaS (Function-as-a-Service) platforms. A widely used mitigation strategy is keeping recently invoked function containers alive in memory to enable warm starts with minimal overhead. This paper identifies new challenges that state-of-the-art FaaS keep-alive policies neglect. These challenges are caused by concurrent function invocations, a common FaaS workload behavior. First, concurrent requests present a tradeoff between reusing busy containers (delayed warm starts) versus cold-starting containers. Second, concurrent requests cause imbalanced evictions of containers that will be reused shortly thereafter. To tackle the challenges, we propose a novel serverless function container orchestration algorithm called CIDRE. CIDRE makes informed decisions to speculatively choose between a delayed warm start and a cold start under concurrency-driven function scaling. CIDRE uses both fine-grained container-level and coarse-grained concurrency information to make balanced eviction decisions. We evaluate CIDRE extensively using two production FaaS workloads. Results show that CIDRE reduces the cold start ratio and the average invocation overhead by up to 75.1% and 39.3% compared to state-of-the-art function keep-alive policies.

As the first Byzantine fault-tolerant (BFT) protocol with linear communication complexity, HotStuff (PODC 2019) has received significant attention. HotStuff has three round-trips for both normal case operations and view change protocols. Follow-up studies attempt to reduce the number of phases for HotStuff. However, most studies give up on one thing in return for another. This paper extends our previous work Marlin (DSN 2022) to Pike, another BFT protocol with two phases and linear communication complexity. Both Pike and Marlin use the same cryptographic tools as in HotStuff and introduce no additional assumptions. Marlin has a more efficient view change (i.e., leader election) protocol but a more complicated data structure. Pike further simplifies the data structure at the cost of longer view changes in extreme cases. We implement the Pike, Marlin, HotStuff, and HotStuff-2, showing that both Pike and Marlin outperform HotStuff in normal case operations.

It is a long-lasting goal to design an embodied system that can solve long-horizon open-world tasks in human-like ways. However, existing approaches usually struggle with compound difficulties caused by the logic-aware decompo-sition and context-aware execution of these tasks. To this end, we introduce MP5, an open-ended multimodal em-bodied system built upon the challenging Minecraft sim-ulator, which can decompose feasible sub-objectives, de-sign sophisticated situation-aware plans, and perform em-bodied action control, with frequent communication with a goal-conditioned active perception scheme. Specifically, MP5 is developed on top of recent advances in Multimodal Large Language Models (MLLMs), and the system is mod-ulated into functional modules that can be scheduled and collaborated to ultimately solve pre-defined context- and process-dependent tasks. Extensive experiments prove that MP5 can achieve a 22% success rate on difficult process-dependent tasks and a 91 % success rate on tasks that heav-ily depend on the context. Moreover, MP5 exhibits a re-markable ability to address many open-ended tasks that are entirely novel. Please see the project page at https: //iranqin. github.io/MP5. github.io/.