Avoiding state enumeration in dynamic checking of distributed programs
Notice bibliographique
Résumé
Distributed programs are particularly vulnerable to software faults. Bugs in these programs are usually very hard to detect without automatic verification. The idea of checking an expected property in a given distributed program run (also referred to as runtime verification) has recently been attracting a great deal of attention for analyzing execution traces to ensure the reliability and dependability of distributed programs. Due to concurrency, the number of global states of a distributed program run tends to grow exponentially with respect to the number of program statements executed. As a result, checking the satisfaction of a property in a given distributed program run can incur significant overhead. This thesis introduces various ideas and exploits them to develop efficient dynamic property checking algorithms. These include the use of atom, introducing and exploiting the notion of serialization and finally proposing a methodology that exploits the concept of atoms and partial order semantics to specify and to check properties of distributed programs. The abstract specification of a distributed program can be mapped to the lower level implementation by labeling the code blocks that belong to the abstract functionalities of the program that are expected to be performed atomically. Each labeled code block is called an atom. Dynamically, an atom includes all the events that result from executing the selected statements from the corresponding code block. An efficient on-the-fly atomicity error detection algorithm has been developed. It is shown that if a run of a distributed program is atomic then the required properties can be checked on a reduced lattice, referred to as the atomic state lattice, which is significantly smaller than the original state lattice. Even with atomization, the number of global states can still grow exponentially in the number of atoms executed. However, when a number of processes has to maintain a property, we expect that each process will be, at some point in time, aware of the events of other processes that may affect the property. Consequently, it is not necessary to check the property in each state. Only synchronized states, where processes have already exchanged the information necessary to maintain the property, need to be considered. These states can be characterized by a synchronization predicate. Serialization of synchronized states is the minimal avenue for a set of processes to exchange the necessary information to maintain a property. Two efficient algorithms to check the satisfaction of a property in a distributed computation in cases where the synchronization predicate is conjunctive or disjunctive have been developed. Finally, a methodology based on the concept of atoms and a partially ordered multi-set (POMSET) model to specify and to check distributed programs properties has been proposed. The POMSET model promotes the separation of two different concerns in specifying and checking properties, namely, the ordering requirements and the computational requirements. A methodology to specify and to efficiently check the two requirements has been introduced.
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Prédiction machine sur la base complète
Imitation des enseignantsNi prévalence calibrée, ni vérité terrain. Validation humaine à venir. Le volet Gemma est une étiquette directe du modèle pour chaque travail de la base, lue sur la notice réduite au titre. Le volet Codex est un classifieur appris des 10 348 étiquettes directes de Codex et calibré sur les taux pondérés de l'échantillon; les champs sans appui suffisant ne portent aucun appel Codex. Le mode candidate est l'union des deux volets; le consensus est leur intersection. Ces sorties portent le statut machine_predicted_unvalidated et ne sont pas des étiquettes humaines.
Scores du classifieur distillé par catégorie (deux têtes)
| Catégorie | Codex | Gemma |
|---|---|---|
| Métarecherche | 0,004 | 0,017 |
| Méta-épidémiologie (sens strict) | 0,001 | 0,001 |
| Méta-épidémiologie (sens large) | 0,001 | 0,002 |
| Bibliométrie | 0,001 | 0,001 |
| Études des sciences et des technologies | 0,001 | 0,005 |
| Communication savante | 0,003 | 0,004 |
| Science ouverte | 0,002 | 0,003 |
| Intégrité de la recherche | 0,001 | 0,002 |
| Charge utile insuffisante (le modèle a refusé de juger) | 0,002 | 0,000 |
Scores machine (provisoires)
Les deux têtes enseignantes du modèle étudiant, lues sur ce travail. Un score ordonne la base pour la relecture; il n'affirme jamais une catégorie, et le statut de validation accompagne chaque rangée tel quel.
Scores de référence d'un modèle non mature (critères de maturité non atteints, 7 itérations). Un score ordonne; il n'affirme jamais une catégorie.
score_only:v0-immature-baseline · tel quel depuis la passe de notation : score_only signifie que le nombre peut ordonner les travaux, et qu'aucune étiquette de catégorie n'en découleClassification
machine, non validéePrédiction automatique; un appel candidat d’une seule source (Gemma direct ou Codex distillé), pas un consensus.
Le détail, modèle par modèle et score par score, se trouve en fin de page sous « Comment cette classification a été obtenue ».