UniHeap: Managing Persistent Objects Across Managed Runtimes for Non-Volatile Memory

Byte-addressable, non-volatile memory (NVM) is emerging as a promising technology. To facilitate its wide adoption, employing NVM in managed runtimes like JVM has proven to be an effective approach (i.e., managed NVM). However, such an approach is runtime specific, which lacks a generic abstraction across different managed languages. Similar to the well-known filesystem primitives that allow diverse programs to access same files via the block I/O interface, managed NVM deserves the same system-wide property for persistent objects across managed runtimes with low overhead. In this paper, we present UniHeap, a new NVM framework for managing persistent objects. It proposes a unified persistent object model that supports various managed languages, and manages NVM within a shared heap that enables cross-language persistent object sharing. UniHeap reduces the object persistence overhead by managing the shared heap in a log-structured manner and coalescing object updates during the garbage collection. We implement UniHeap as a generic framework and extend it to different managed runtimes that include HotSpot JVM, cPython, and JavaScript engine SpiderMonkey. We evaluate UniHeap with a variety of applications, such as key-value store and transactional database. Our evaluation shows that UniHeap significantly outperforms state-of-the-art object sharing approaches, while introducing negligible overhead to the managed runtimes.Comment: A 2 page extended abstract for NVMW 2022

RackBlox: A Software-Defined Rack-Scale Storage System with Network-Storage Co-Design

Software-defined networking (SDN) and software-defined flash (SDF) have been serving as the backbone of modern data centers. They are managed separately to handle I/O requests. At first glance, this is a reasonable design by following the rack-scale hierarchical design principles. However, it suffers from suboptimal end-to-end performance, due to the lack of coordination between SDN and SDF. In this paper, we co-design the SDN and SDF stack by redefining the functions of their control plane and data plane, and splitting up them within a new architecture named RackBlox. RackBlox decouples the storage management functions of flash-based solid-state drives (SSDs), and allow the SDN to track and manage the states of SSDs in a rack. Therefore, we can enable the state sharing between SDN and SDF, and facilitate global storage resource management. RackBlox has three major components: (1) coordinated I/O scheduling, in which it dynamically adjusts the I/O scheduling in the storage stack with the measured and predicted network latency, such that it can coordinate the effort of I/O scheduling across the network and storage stack for achieving predictable end-to-end performance; (2) coordinated garbage collection (GC), in which it will coordinate the GC activities across the SSDs in a rack to minimize their impact on incoming I/O requests; (3) rack-scale wear leveling, in which it enables global wear leveling among SSDs in a rack by periodically swapping data, for achieving improved device lifetime for the entire rack. We implement RackBlox using programmable SSDs and switch. Our experiments demonstrate that RackBlox can reduce the tail latency of I/O requests by up to 5.8x over state-of-the-art rack-scale storage systems.Comment: 14 pages. Published in published in ACM SIGOPS 29th Symposium on Operating Systems Principles (SOSP'23

Restoring a Salmon Spawning Stream to the Jericho Watershed

The Jericho Lands is a 21-hectare plot of land located in the West Point Grey neighbourhood of Vancouver. It is directly upslope of Jericho Park, which itself has significant ecological and recreational value to the community. Jericho Lands is currently planned to undergo redevelopment in the coming years by the Musqueam, Squamish, and Tsleil-Waututh First Nations and is currently in the research, planning, and consulting stage. This redevelopment could make it possible to restore salmon-spawning streams that once existed in the area. The aim of this project is to explore the possibility of re-introducing salmon to Jericho Park. The main objectives of our project are to explore the characteristics of Jericho Park using GIS software, explore water sources, propose potential locations for possible holding ponds, and propose possible stream routes for these holding ponds. Chum were determined to be the best species for reintroduction at the park based on a meeting that we had with Scott Hinch, an aquatic ecologist at UBC. The criteria for streamflow was based on the biological needs of salmon. The amount of water needed to sustain a healthy salmon stream was determined to be 40 L/s or 0.04 m³/s (1.5 m wide, 0.13 m deep, flowing at 0.20 m/s). This streamflow would be needed from November to the end of April. In other months (May through October), we set a target streamflow (0.00039 m³/s to 0.0027 m³/s) to mitigate potential evapotranspiration in order to keep the channel wet, but not necessarily flowing. There are currently two watersheds contributing to Jericho Park, which provide two possibilities for stream channel locations. The western watershed is 230 ha and eastern is 264 ha. Both have 62% impervious cover (including roads, roofs, etc.). Because of the urban nature of the system, streamflow is likely to rely on storm sewers and streamflow might be very flashy (i.e., short floods followed by periods of very low flow). An analysis of surface water was carried out to estimate potential streamflow. This was done using water balance equations with weather parameters from 2016, parameters obtained from literature, municipal databases, and GIS software. Weather data from 2016 was used for water balance equations. Stormwater would be the main water source for the stream. However, not all watersheds could reach the target flow rate (0.04 m³/s). The average streamflow from November to April would be 0.05 m³/s in the eastern watershed, which is greater than the target flow rate. Meanwhile, the western watershed only has average streamflow of 0.024 m³/s during this period. Holding ponds could be used to help prevent the flashiness of a stream and store water for use in April, but a holding pond would have to be enormous (103680 m³, the size of a football field 19 m deep) to give 0.04 m³/s of water for one month. HVAC (Heating, Ventilation, and Air Conditioning) systems could produce 14 to 46 L/day/1000 ft² during the summer. This would be enough, given a reasonable number of newly developed buildings in Jericho Lands, to mitigate evapotranspiration in the stream channel, and help mitigate water losses from evaporation and plant uptake in the channel and the existing ponds in Jericho Park. However, it would not be of use for the spawning season as there would be no Chum in the stream throughout the summer. We have proposed two possible locations of holding ponds as well as the resulting stream that would be constructed at each possible location shown in Figures 9 and 10, section 3.5. The holding pond proposed in Figure 9 could be possible with sufficient groundwater pumping, although dry seasons could be a problem. However, the holding pond proposed in Figure 10 would provide enough water during a dry season due to its water input mainly sourced from the eastern stormwater catchment.Science, Faculty ofEarth, Ocean and Atmospheric Sciences, Department ofUnreviewedUndergraduat

Tissue‐Adaptive Materials with Independently Regulated Modulus and Transition Temperature

International audienceThe ability of living species to transition between rigid and flexible shapes represents one of their survival mechanisms, which has been adopted by various human technologies. Such transition is especially desired in medical devices as rigidity facilitates the implantation process, while flexibility and softness favor biocompatibility with surrounding tissue. Traditional thermoplastics cannot match soft tissue mechanics, while gels leach into the body and alter their properties over time. Here, a single-component system with an unprecedented drop of Young's modulus by up to six orders of magnitude from the GPa to kPa level at a controlled temperature within 28-43 °C is demonstrated. This approach is based on brush-like polymer networks with crystallizable side chains, e.g., poly(valerolactone), affording independent control of melting temperature and Young's modulus by concurrently altering side chain length and crosslink density. Softening down to the tissue level at the physiological temperature allows the design of tissue-adaptive implants that can be inserted as rigid devices followed by matching the surrounding tissue mechanics at body temperature. This transition also enables thermally triggered release of embedded drugs for anti-inflammatory treatment

Additional file 1 of Gut microbiota dynamics and fecal SCFAs after colonoscopy: accelerating microbiome stabilization by Clostridium butyricum

Additional file 1: Figure S1. Faecal samples and intestinal contents were collected from 11 subjects at 8 time points before, during and 60 days after colonoscopy. NA denotes an incurred sample loss. Figure S2. The ratio of Firmicutes and Bacteroidetes showed the longitudinal fluctuation patterns of gut microbiota in the Control group. **p < 0.01. Figure S3. Quantity of buks containing bacteria stains at the phylum level. Figure S4. The ratio of Firmicutes and Bacteroidetes showed the longitudinal fluctuation patterns of gut microbiota in the Clostridium Butyricum group. **p < 0.01