Chi: a scalable and programmable control plane for distributed stream processing systems

Stream-processing workloads and modern shared cluster environments exhibit high variability and unpredictability. Combined with the large parameter space and the diverse set of user SLOs, this makes modern streaming systems very challenging to statically configure and tune. To address these issues, in this paper we investigate a novel control-plane design, Chi, which supports continuous monitoring and feedback, and enables dynamic re-configuration. Chi leverages the key insight of embedding control-plane messages in the data-plane channels to achieve a low-latency and flexible control plane for stream-processing systems. Chi introduces a new reactive programming model and design mechanisms to asynchronously execute control policies, thus avoiding global synchronization. We show how this allows us to easily implement a wide spectrum of control policies targeting different use cases observed in production. Large-scale experiments using production workloads from a popular cloud provider demonstrate the flexibility and efficiency of our approach

Crystal structure of (E)-diethyl 2-[(1-phenylsulfonyl-1H-indol-3-yl)methylidene]succinate

In the title compound, C23H23NO6S, the phenyl ring is perpendicular [dihedral angle = 89.34 (9)°] to the indole ring system. In the molecule, the ethoxy groups are each disordered over two sets of sites with occupancy ratios of 0.671 (6):0.329 (6) and 0.75 (3):0.25 (3). The molecular conformation is consolidated by a weak C—H...O interaction, which generates an S(6) graph–set motif. The packing of the molecules in the crystal structure features weak C—H...π interactions

Crystal structure of 2-[2-phenyl-1-(phenylsulfonyl)ethyl]-1-phenylsulfonyl-1H-indole

In the title compound, C28H23NO4S2, the indole ring system (r.m.s. deviation = 0.007 Å) subtends dihedral angles of 78.69 (13) and 38.97 (13)° with the planes of the N- and C-bonded sulfonylbenzene rings, respectively, and these two benzene rings are inclined to each other at an angle of 65.45 (16)°. The methylene-linked phenyl ring is twisted at an angle of 81.80 (13)° from the indole ring. The molecular structure features two short intramolecular C—H...O contacts, which both generate S(6) rings. In the crystal, molecules are linked by C—H...O hydrogen bonds and C—H...π interactions, generating a three-dimensional network

Where the sidewalk ends: Extending the internet as graph using traceroutes from P2P users

An accurate Internet topology graph is important in many areas of networking, from understanding ISP business relationships to diagnosing network anomalies. Most Internet mapping efforts have derived the network structure, at the level of interconnected autonomous systems (ASes), from a rather limited set of vantage points. In this paper, we argue that a promising approach to revealing the hidden areas of the Internet topology is through active measurement from an observation platform that scales with the growing Internet. By leveraging measurements performed by an extension to a popular P2P system, we show that this approach indeed exposes significant new topological information. Our study is based on traceroute measurements from more than 992,000 IPs in over 3,700 ASes distributed across the Internet hierarchy, many in regions of the Internet not covered by publicly available path information. To address this issue we develop heuristics that identify 23,914 new AS links not visible in the publicly-available BGP data-12.86 percent more customer-provider links and 40.99 percent more peering links, than previously reported. We validate our heuristics using data from a tier-1 ISP, and show that they successfully filter out all false links introduced by public IP-to-AS mapping. We analyze properties of the Internet graph that includes these new links and characterize why they are missing. Finally, we have made the identified set of links and their inferred relationships publicly available. © 1968-2012 IEEE

Compressive and Flexural Strength of Concrete with Different Nanomaterials: A Critical Review

With recent technological advances, adding nanomaterials as a reinforcement material in concrete has gained immense attention. This review paper aims to report advances in the form of a one-stop shop catering to methods that focus on improving the quality of traditional concrete. Nanoparticles—the elementary form of nanomaterials—are proven to enhance the strength and longevity of concrete. Nanosilica, nanoalumina, nanometakaolin, carbon nanotubes, and nanotitanium oxide are modern nanomaterials that have demonstrated strong evidence of enhancing concrete quality, which supports infrastructure building and long-term monitoring. Nanoconcrete—an exciting prospect extending the boundaries of traditional civil engineering—exhibited increased compressive and flexural strength using elementary compounds. In particular, the rigorous research survey of many articles reveals an increase in compressive strength from 20% to 63% by replacing the cement with different nanomaterials in different percentages and flexural strength from 16% to 47%