Invalidity dossier
US 5991808
Added 9/23/2026, 6:19:02 PM
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Patent summary
Title, assignee, inventors, filing/issue dates, abstract, and a plain-language overview of the claims.
US5991808A — "Task processing optimization in a multiprocessor system"
Bibliographic data (from supplied excerpt)
- Patent number: US5991808A; application US08/867,095, filed 1997-06-02
- Priority date: 1997-06-02; granted/publication date: 1999-11-23
- Inventors: Andrei Broder, Michael Mitzenmacher
- Original assignee: Digital Equipment Corp.; current assignee listed: Hewlett Packard Enterprise Development LP
- Legal status listed: Expired – Lifetime (anticipated expiration 2017-06-02)
- Classification: G06F9/505 (resource allocation considering load)
Purpose
The patent addresses load balancing where tasks ("items") choose a server but load information may be stale. The excerpt explains that querying all servers for exact current loads is unrealistic and that "herding" can occur when many clients act on stale data, sending tasks to a server that appears least loaded but is actually heavily loaded.
Plain-language scope (per the excerpt)
A task directing unit (client) selects a small subset of the resources uniformly at random (u.a.r.)—at least 1, substantially fewer than all, preferably 2, with no more than 20% of resources—queries those resources for load information (often stale), identifies the least loaded among them, and directs the item there; ties may be broken arbitrarily. Resources may be processors in one multiprocessor workstation or separate single-processor computers; the system may be homogeneous or heterogeneous (with weighted queue loadings). Priorities may be assigned per user or item type. Instructions may be stored on a storage medium and read by the task directing unit processor. Figures 1–9 illustrate the system, performance graphs, and a client computer and multiprocessor workstation.
Not established by the excerpt
The excerpt is incomplete ("[Excerpt only; consult the source for omitted text.]"). It does not provide the full specification, all claims or claim language, the complete reference list or detailed description, or the omitted text after the discussion of transmission delay. It does not establish validity, enforceability, litigation, or the accuracy of the listed assignee/status data.
Source: https://patents.google.com/patent/[US5991808](/patent/US5991808)/en
Generated 10/1/2026, 9:42:51 PM
Cases on file (0)
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Litigation summary
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Proceedings on file (0)
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No PTAB proceedings on file. This patent has not been challenged via IPR, PGR, or CBM. The absence is itself a signal — well-asserted patents eventually attract IPRs. The LLM analysis below may surface filings the ODP feed hasn’t indexed yet.
PTAB challenges
AIA trial proceedings at the USPTO Patent Trial and Appeal Board — IPR, PGR, and CBM. Petitioners, judge panels, claim-level invalidation outcomes from Final Written Decisions, and Federal Circuit appeals. The single most important defensive datapoint after litigation history.
Assignment history
Inventors, original assignee, and the chain of ownership recorded with the USPTO — including the correspondent attorney who recorded each assignment, since shell-LLC chains often share one repeat-player attorney even when the entity names look unrelated. Surfaces NPE / patent-troll patterns: shell-entity transfers, known asserters in the chain, repeat correspondent fingerprints, pre-litigation assignments, and bankruptcy fire-sales.
Prior art
Earlier patents, publications, and products that may anticipate or render the claims unpatentable.
Obviousness
Combinations of prior art that suggest the claimed invention would have been obvious under 35 U.S.C. § 103.
Extensions
Patent term adjustments, term extensions, continuations, divisionals, family members, and expiration dates.
Derivative works
Defensive disclosure: derivative variations of each claim designed to render future incremental improvements obvious or non-novel.