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Effectively exploiting emerging far-memory technology requires consideration of operating on richly connected data outside the context of the parent process. Operating-system technology in development offers help by exposing abstractions such as memory objects and globally invariant pointers that can be traversed by devices and newly instantiated compute. Such ideas will allow applications running on future heterogeneous distributed systems with disaggregated memory nodes to exploit near-memory processing for higher performance and to independently scale their memory and compute resources for lower cost. 

We present 3MileBeach, a tracing and fault injection platform designed for microservice-based architectures. 3Mile-Beach interposes on the message serialization libraries that are ubiquitous in this environment, avoiding the application code instrumentation that tracing and fault injection infrastructures typically require. 3MileBeach provides message-level distributed tracing at less than 50% of the overhead of the state-of-the-art tracing frameworks, and fault injection that allows higher precision experiments than existing solutions. We measure the overhead of 3MileBeach as a tracer and its efficacy as a fault injector. We qualitatively measure its promise as a platform for tuning and debugging by sharing concrete use cases in the context of bottleneck identification, performance tuning, and bug finding. Finally, we use 3MileBeach to perform a novel type of fault injection - Temporal Fault Injection (TFI), which more precisely controls individual inter-service message flow with temporal prerequisites, and makes it possible to catch an entirely new class of fault tolerance bugs. 

Byte-addressable, non-volatile memory (NVM) presents an opportunity to rethink the entire system stack. We present Twizzler, an operating system redesign for this near-future. Twizzler removes the kernel from the I/O path, provides programs with memory-style access to persistent data using small (64 bit), object-relative cross-object pointers, and enables simple and efficient long-term sharing of data both between applications and between runs of an application. Twizzler provides a clean-slate programming model for persistent data, realizing the vision of Unix in a world of persistent RAM. We show that Twizzler is simpler, more extensible, and more secure than existing I/O models and implementations by building software for Twizzler and evaluating it on NVM DIMMs. Most persistent pointer operations in Twizzler impose less than 0.5 ns added latency. Twizzler operations are up to faster than Unix , and SQLite queries are up to faster than on PMDK. YCSB workloads ran 1.1– faster on Twizzler than on native and NVM-optimized SQLite backends. 

Distributed systems are hard to reason about largely because of uncertainty about what may go wrong in a particular execution, and about whether the system will mitigate those faults. Tools that perturb executions can help test whether a system is robust to faults, while tools that observe executions can help better understand their system-wide effects. We present Box of Pain, a tracer and fault injector for unmodified distributed systems that addresses both concerns by interposing at the system call level and dynamically reconstructing the partial order of communication events based on causal relationships. Box of Pain’s lightweight approach to tracing and focus on simulating the effects of partial failures on communication rather than the failures themselves sets it apart from other tracing and fault injection systems. We present evidence of the promise of Box of Pain and its approach to lightweight observation and perturbation of distributed systems.