{"id":{"repo_id":"uiuc","oai_identifier":"oai:www.ideals.illinois.edu:2142/132527"},"canonical_url":"https://search.dev.ndltd.org/etd/uiuc/oai:www.ideals.illinois.edu:2142/132527","repository":{"repo_id":"uiuc","name":"University of Illinois - Urbana-Champaign","base_url":"https://www.ideals.illinois.edu/oai-pmh"},"display":{"title":"Rethinking communication libraries for asynchronous multithreaded runtimes","abstract":"The evolution of architectures, algorithms, and programming models is driving communication toward greater asynchrony and concurrency, often in multithreaded environments. A representative example is the Asynchronous Many-Task (AMT) model, which emphasizes fine-grained message-driven execution. However, existing communication libraries, most notably MPI, were not originally designed to support massive thread-level concurrency or highly asynchronous control flows, making them a major bottleneck in scaling AMT systems on modern multicore and heterogeneous architectures. Although recent MPI extensions, such as Virtual Communication Interfaces (VCIs) and Continuations, attempt to address these limitations, they remain constrained by backward compatibility burdens and legacy runtime designs. This dissertation rethinks the design of communication libraries from the ground up, introducing the Lightweight Communication Interface (LCI), a communication library built from the ground up for asynchronous multithreaded communication. LCI provides a unified interface that supports common point-to-point primitives and diverse synchronization mechanisms, along with flexible controls for incrementally fine-tuning resource assignment and runtime behavior. It features a threading-efficient runtime built on atomic data structures, fine-grained non-blocking locks, and low-level network insights. It achieves scalable multithreaded performance without sacrificing simplicity or portability. We evaluate LCI and its integrations within two major AMT runtimes, including HPX and Charm++. In HPX, the LCI parcelport achieves higher message rates and lower latencies than its best MPI-based designs while requiring fewer communication contexts. In Charm++, we collaborated with the Charm++ development team to develop ReConverse, a modern reimplementation of the Converse communication substrate featuring a modular backend abstraction. The LCI backend within ReConverse eliminates the need for a dedicated communication thread and delivers order-of-magnitude performance improvements in latency, message rate, and real-world application throughput compared to its existing UCX and OFI machine layers. The results demonstrate that the fundamental barriers to multithreaded scalability stem not from hardware limitations but from legacy software abstractions. By relaxing unnecessary synchronization constraints and co-designing the interface and runtime around asynchrony, it is possible to achieve both flexibility and efficiency at scale. LCI and its integrations into HPX and Charm++ establish a practical path toward next-generation communication systems that treat multithreading and message-driven execution not as challenges, but as first principles for performance and programmability in high-performance computing.","abstract_html":"The evolution of architectures, algorithms, and programming models is driving communication toward greater asynchrony and concurrency, often in multithreaded environments. A representative example is the Asynchronous Many-Task (AMT) model, which emphasizes fine-grained message-driven execution. However, existing communication libraries, most notably MPI, were not originally designed to support massive thread-level concurrency or highly asynchronous control flows, making them a major bottleneck in scaling AMT systems on modern multicore and heterogeneous architectures. Although recent MPI extensions, such as Virtual Communication Interfaces (VCIs) and Continuations, attempt to address these limitations, they remain constrained by backward compatibility burdens and legacy runtime designs. This dissertation rethinks the design of communication libraries from the ground up, introducing the Lightweight Communication Interface (LCI), a communication library built from the ground up for asynchronous multithreaded communication. LCI provides a unified interface that supports common point-to-point primitives and diverse synchronization mechanisms, along with flexible controls for incrementally fine-tuning resource assignment and runtime behavior. It features a threading-efficient runtime built on atomic data structures, fine-grained non-blocking locks, and low-level network insights. It achieves scalable multithreaded performance without sacrificing simplicity or portability. We evaluate LCI and its integrations within two major AMT runtimes, including HPX and Charm++. In HPX, the LCI parcelport achieves higher message rates and lower latencies than its best MPI-based designs while requiring fewer communication contexts. In Charm++, we collaborated with the Charm++ development team to develop ReConverse, a modern reimplementation of the Converse communication substrate featuring a modular backend abstraction. The LCI backend within ReConverse eliminates the need for a dedicated communication thread and delivers order-of-magnitude performance improvements in latency, message rate, and real-world application throughput compared to its existing UCX and OFI machine layers. The results demonstrate that the fundamental barriers to multithreaded scalability stem not from hardware limitations but from legacy software abstractions. By relaxing unnecessary synchronization constraints and co-designing the interface and runtime around asynchrony, it is possible to achieve both flexibility and efficiency at scale. LCI and its integrations into HPX and Charm++ establish a practical path toward next-generation communication systems that treat multithreading and message-driven execution not as challenges, but as first principles for performance and programmability in high-performance computing.","abstract_has_math":false,"creators":["Yan, Jiakun"],"institution":"University of Illinois Urbana-Champaign","degree_name":"Ph.D.","degree_level":"Dissertation","degree_discipline":"Computer Science","degree_department":null,"school":null,"contributors":["Snir, Marc","Gropp, William","Kale, Laxmikant","Yelick, Katherine","Guo, Yanfei","Kaiser, Hartmut"],"advisors":[],"committee_chairs":[],"committee_members":[],"year":2025,"date_issued":"2025-12","date_published":"2025-12","updated_at":"2026-07-22T22:25:07Z","subjects":["Communication library","MPI","Multithreaded message passing","Task parallel","Asynchronous many-task systems"],"languages":["en"],"rights":["Copyright 2025 Jiakun Yan"],"rights_urls":[],"identifier_entries":[]},"links":{"outbound_url":"https://hdl.handle.net/2142/132527","outbound_label":"Handle","outbound_source":"dc:identifier"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:contributor","label":"Contributor","values":["Snir, Marc","Gropp, William","Kale, Laxmikant","Yelick, Katherine","Guo, Yanfei","Kaiser, Hartmut"]},{"key":"dc:creator","label":"Author","values":["Yan, Jiakun"]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"dc:date","label":"Dc Date","values":["2025-12","2025-11-25"]},{"key":"dc:type","label":"Dc Type","values":["text","Thesis"]},{"key":"thesis:degree_discipline","label":"Discipline","values":["Computer Science"]},{"key":"thesis:degree_level","label":"Degree Level","values":["Dissertation"]},{"key":"thesis:degree_name","label":"Degree Name","values":["Ph.D."]},{"key":"thesis:institution_name","label":"Thesis Institution Name","values":["University of Illinois Urbana-Champaign"]}]},{"id":"subjects_keywords","label":"Subjects and Keywords","entries":[{"key":"dc:subject","label":"Dc Subject","values":["Communication library","MPI","Multithreaded message passing","Task parallel","Asynchronous many-task systems"]}]},{"id":"language_rights","label":"Language and Rights","entries":[{"key":"dc:language","label":"Dc Language","values":["en"]},{"key":"dc:rights","label":"Dc Rights","values":["Copyright 2025 Jiakun Yan"]}]},{"id":"identifiers","label":"Identifiers","entries":[{"key":"dc:identifier","label":"Identifier","values":["https://hdl.handle.net/2142/132527"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description","label":"Description","values":["The evolution of architectures, algorithms, and programming models is driving communication toward greater asynchrony and concurrency, often in multithreaded environments. A representative example is the Asynchronous Many-Task (AMT) model, which emphasizes fine-grained message-driven execution. However, existing communication libraries, most notably MPI, were not originally designed to support massive thread-level concurrency or highly asynchronous control flows, making them a major bottleneck in scaling AMT systems on modern multicore and heterogeneous architectures. Although recent MPI extensions, such as Virtual Communication Interfaces (VCIs) and Continuations, attempt to address these limitations, they remain constrained by backward compatibility burdens and legacy runtime designs. This dissertation rethinks the design of communication libraries from the ground up, introducing the Lightweight Communication Interface (LCI), a communication library built from the ground up for asynchronous multithreaded communication. LCI provides a unified interface that supports common point-to-point primitives and diverse synchronization mechanisms, along with flexible controls for incrementally fine-tuning resource assignment and runtime behavior. It features a threading-efficient runtime built on atomic data structures, fine-grained non-blocking locks, and low-level network insights. It achieves scalable multithreaded performance without sacrificing simplicity or portability. We evaluate LCI and its integrations within two major AMT runtimes, including HPX and Charm++. In HPX, the LCI parcelport achieves higher message rates and lower latencies than its best MPI-based designs while requiring fewer communication contexts. In Charm++, we collaborated with the Charm++ development team to develop ReConverse, a modern reimplementation of the Converse communication substrate featuring a modular backend abstraction. The LCI backend within ReConverse eliminates the need for a dedicated communication thread and delivers order-of-magnitude performance improvements in latency, message rate, and real-world application throughput compared to its existing UCX and OFI machine layers. The results demonstrate that the fundamental barriers to multithreaded scalability stem not from hardware limitations but from legacy software abstractions. By relaxing unnecessary synchronization constraints and co-designing the interface and runtime around asynchrony, it is possible to achieve both flexibility and efficiency at scale. LCI and its integrations into HPX and Charm++ establish a practical path toward next-generation communication systems that treat multithreading and message-driven execution not as challenges, but as first principles for performance and programmability in high-performance computing.","Submission original under an indefinite embargo labeled 'Open Access'. The submission was exported from vireo on 2026-02-19 without embargo terms","The student, Jiakun Yan, accepted the attached license on 2025-11-24 at 18:52.","The student, Jiakun Yan, submitted this Dissertation for approval on 2025-11-24 at 19:04.","This Dissertation was approved for publication on 2025-11-25 at 09:12.","DSpace SAF Submission Ingestion Package generated from Vireo submission #22941 on 2026-02-19 at 18:25:17"]},{"key":"dc:format","label":"Dc Format","values":["application/pdf"]},{"key":"dc:title","label":"Title","values":["Rethinking communication libraries for asynchronous multithreaded runtimes"]}]}],"canonical_facts":{"dc:contributor":["Snir, Marc","Gropp, William","Kale, Laxmikant","Yelick, Katherine","Guo, Yanfei","Kaiser, Hartmut"],"dc:creator":["Yan, Jiakun"],"dc:date":["2025-12","2025-11-25"],"dc:description":["The evolution of architectures, algorithms, and programming models is driving communication toward greater asynchrony and concurrency, often in multithreaded environments. A representative example is the Asynchronous Many-Task (AMT) model, which emphasizes fine-grained message-driven execution. However, existing communication libraries, most notably MPI, were not originally designed to support massive thread-level concurrency or highly asynchronous control flows, making them a major bottleneck in scaling AMT systems on modern multicore and heterogeneous architectures. Although recent MPI extensions, such as Virtual Communication Interfaces (VCIs) and Continuations, attempt to address these limitations, they remain constrained by backward compatibility burdens and legacy runtime designs. This dissertation rethinks the design of communication libraries from the ground up, introducing the Lightweight Communication Interface (LCI), a communication library built from the ground up for asynchronous multithreaded communication. LCI provides a unified interface that supports common point-to-point primitives and diverse synchronization mechanisms, along with flexible controls for incrementally fine-tuning resource assignment and runtime behavior. It features a threading-efficient runtime built on atomic data structures, fine-grained non-blocking locks, and low-level network insights. It achieves scalable multithreaded performance without sacrificing simplicity or portability. We evaluate LCI and its integrations within two major AMT runtimes, including HPX and Charm++. In HPX, the LCI parcelport achieves higher message rates and lower latencies than its best MPI-based designs while requiring fewer communication contexts. In Charm++, we collaborated with the Charm++ development team to develop ReConverse, a modern reimplementation of the Converse communication substrate featuring a modular backend abstraction. The LCI backend within ReConverse eliminates the need for a dedicated communication thread and delivers order-of-magnitude performance improvements in latency, message rate, and real-world application throughput compared to its existing UCX and OFI machine layers. The results demonstrate that the fundamental barriers to multithreaded scalability stem not from hardware limitations but from legacy software abstractions. By relaxing unnecessary synchronization constraints and co-designing the interface and runtime around asynchrony, it is possible to achieve both flexibility and efficiency at scale. LCI and its integrations into HPX and Charm++ establish a practical path toward next-generation communication systems that treat multithreading and message-driven execution not as challenges, but as first principles for performance and programmability in high-performance computing.","Submission original under an indefinite embargo labeled 'Open Access'. The submission was exported from vireo on 2026-02-19 without embargo terms","The student, Jiakun Yan, accepted the attached license on 2025-11-24 at 18:52.","The student, Jiakun Yan, submitted this Dissertation for approval on 2025-11-24 at 19:04.","This Dissertation was approved for publication on 2025-11-25 at 09:12.","DSpace SAF Submission Ingestion Package generated from Vireo submission #22941 on 2026-02-19 at 18:25:17"],"dc:format":["application/pdf"],"dc:identifier":["https://hdl.handle.net/2142/132527"],"dc:language":["en"],"dc:rights":["Copyright 2025 Jiakun Yan"],"dc:subject":["Communication library","MPI","Multithreaded message passing","Task parallel","Asynchronous many-task systems"],"dc:title":["Rethinking communication libraries for asynchronous multithreaded runtimes"],"dc:type":["text","Thesis"],"thesis:degree_discipline":["Computer Science"],"thesis:degree_level":["Dissertation"],"thesis:degree_name":["Ph.D."],"thesis:institution_name":["University of Illinois Urbana-Champaign"]},"updated_at":"2026-07-22T22:25:07Z"}