cooperative task management without manual stack management or presented by tina swenson cs533 -...
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Cooperative Task Management without Manual Stack
ManagementOR
Presented by Tina Swenson CS533 - February 12, 2007
Event-driven Programming is Not the Opposite of Threaded Programming
Published by USENIX2002 Annual Technical Conference
Cooperative Task Management without Manual Stack Management
The Authors
Atul Adya PhD MIT. Boston, MA
Thor – distributed, object-oriented database
Microsoft Research. Redmond, WA Farsite – serverless, distributed file system http://research.microsoft.com/Farsite/
et al. (Howell, Theimer, Bolosky, Douceur)
Cooperative Task Management without Manual Stack Management
Paper’s Goal
Clarify concepts associated with the event-driven and multi-threaded programming models. The models’ names tend to merge several
concepts and this causes confusion.Present a hybrid approach to allow the two
types of stack management to co-exist in the same software.
Cooperative Task Management without Manual Stack Management
Events vs. Threads The Source of Confusion
Task Management Serial Preemptive
Stack Management Manual Automatic
Cooperative Task Management without Manual Stack Management
Events vs. Threads The Source of Confusion
Task Management Serial Preemptive Cooperative
Stack Management Manual Automatic Hybrid
One can choose cooperative task management while preserving the
automatic stack management.
Cooperative Task Management without Manual Stack Management
Stack Management
Manual (big pain) Event handler registers continuation with EH
scheduler. The continuation creates another EH that knows what to do with original’s info.
Programmer must figure this all out. Better not have bugs.
As the code evolves, managing the stack becomes more unwieldy.
Benefit: Yields are visible in the code.
Cooperative Task Management without Manual Stack Management
Stack Management
Automatic (less pain) Compiler manages stack. Danger: Hidden concurrency.
Solution = Check for declared assumptions.
Cooperative Task Management without Manual Stack Management
Stack Management - Hybrid
The two flavors of stack management both have passionate advocates.
Both flavors can work together via a Hybrid approach. Adapters are used to bridge the two styles.
Cooperative Task Management without Manual Stack Management
Adapter Functions
Main Thread:VerifyCertCFA
Cooperative Task Management without Manual Stack Management
Adapter Functions
VerifyFiber was created by VerifyCertCFA in the MainFiber
Cooperative Task Management without Manual Stack Management
Adapter Functions
Cooperative Task Management without Manual Stack Management
Adapter Functions
Verify Thread: FiberStart
Main Thread:VerifyCertCFA
VerifyCertCFA2
Cooperative Task Management without Manual Stack Management
In Practice
Farsite Started out as traditional event-driven. Code grew, manual-stack-management
became costly. Mechanized the wrapping IO functions.
Cooperative Task Management without Manual Stack Management
What the Authors Think
Task management and stack management are orthogonal concepts.
As code evolves: Event-based programs have the code
restructuring burdon of stack ripping. Both styles must reconfirm invariant logic
because assumptions change, etc.Hybrid-stack-management allows use of
both styles of stack management.
Cooperative Task Management without Manual Stack Management
What I Think