Efficient Monitoring of Parametric Context Free Patterns

Recent developments in runtime verification and monitoring show that parametric regular and temporal logic specifications can be efficiently monitored against large programs. However, these logics reduce to ordinary finite automata, limiting their expressivity. For example, neither can specify structured properties that refer to the call stack of the program. While context-free grammars (CFGs) are expressive and well-understood, existing techniques of monitoring CFGs generate massive runtime overhead in real-life applications. This paper shows for the first time that monitoring parametric CFGs is practical (on the order of 10% or lower for average cases, several times faster than the state-of-the-art). We present a monitor synthesis algorithm for CFGs based on an LR(1) parsing algorithm, modified with stack cloning to account for good prefix matching. In addition, a logic-independent mechanism is introduced to support partial matching, allowing patterns to be checked against fragments of execution traces

Improved multithreaded unit testing.

ABSTRACT Multithreaded code is notoriously hard to develop and test. A multithreaded test exercises the code under test with two or more threads. Each test execution follows some schedule/interleaving of the multiple threads, and different schedules can give different results. Developers often want to enforce a particular schedule for test execution, and to do so, they use time delays (Thread.sleep in Java). Unfortunately, this approach can produce false positives or negatives, and can result in unnecessarily long testing time. This paper presents IMUnit, a novel approach to specifying and executing schedules for multithreaded tests. We introduce a new language that allows explicit specification of schedules as orderings on events encountered during test execution. We present a tool that automatically instruments the code to control test execution to follow the specified schedule, and a tool that helps developers migrate their legacy, sleep-based tests into event-based tests in IMUnit. The migration tool uses novel techniques for inferring events and schedules from the executions of sleep-based tests. We describe our experience in migrating over 200 tests. The inference techniques have high precision and recall of over 75%, and IMUnit reduces testing time compared to sleepbased tests on average 3.39x

Intracoronary artery retrograde thrombolysis combined with percutaneous coronary interventions for ST-segment elevation myocardial infarction complicated with diabetes mellitus: A case report and literature review

BackgroundThe management of a large thrombus burden in patients with acute myocardial infarction and diabetes is still a worldwide problem.Case presentationA 74-year-old Chinese woman presented with ST-segment elevation myocardial infarction (STEMI) complicated with diabetes mellitus and hypertension. Angiography revealed massive thrombus formation in the mid-segment of the right coronary artery leading to vascular occlusion. The sheared balloon was placed far from the occlusion segment and urokinase (100,000 u) was administered for intracoronary artery retrograde thrombolysis, and thrombolysis in myocardial infarction (TIMI) grade 3 blood flow was restored within 7 min. At last, one stent was accurately implanted into the culprit’s vessel. No-reflow, coronary slow flow, and reperfusion arrhythmia were not observed during this process.ConclusionIntracoronary artery retrograde thrombolysis (ICART) can be effectively and safely used in patients with STEMI along with diabetes mellitus and hypertension, even if the myocardial infarction exceeds 12 h (REST or named ICART ClinicalTrials.gov number, ChiCTR1900023849)

31st Annual Meeting and Associated Programs of the Society for Immunotherapy of Cancer (SITC 2016) : part two

Background The immunological escape of tumors represents one of the main ob- stacles to the treatment of malignancies. The blockade of PD-1 or CTLA-4 receptors represented a milestone in the history of immunotherapy. However, immune checkpoint inhibitors seem to be effective in specific cohorts of patients. It has been proposed that their efficacy relies on the presence of an immunological response. Thus, we hypothesized that disruption of the PD-L1/PD-1 axis would synergize with our oncolytic vaccine platform PeptiCRAd. Methods We used murine B16OVA in vivo tumor models and flow cytometry analysis to investigate the immunological background. Results First, we found that high-burden B16OVA tumors were refractory to combination immunotherapy. However, with a more aggressive schedule, tumors with a lower burden were more susceptible to the combination of PeptiCRAd and PD-L1 blockade. The therapy signifi- cantly increased the median survival of mice (Fig. 7). Interestingly, the reduced growth of contralaterally injected B16F10 cells sug- gested the presence of a long lasting immunological memory also against non-targeted antigens. Concerning the functional state of tumor infiltrating lymphocytes (TILs), we found that all the immune therapies would enhance the percentage of activated (PD-1pos TIM- 3neg) T lymphocytes and reduce the amount of exhausted (PD-1pos TIM-3pos) cells compared to placebo. As expected, we found that PeptiCRAd monotherapy could increase the number of antigen spe- cific CD8+ T cells compared to other treatments. However, only the combination with PD-L1 blockade could significantly increase the ra- tio between activated and exhausted pentamer positive cells (p= 0.0058), suggesting that by disrupting the PD-1/PD-L1 axis we could decrease the amount of dysfunctional antigen specific T cells. We ob- served that the anatomical location deeply influenced the state of CD4+ and CD8+ T lymphocytes. In fact, TIM-3 expression was in- creased by 2 fold on TILs compared to splenic and lymphoid T cells. In the CD8+ compartment, the expression of PD-1 on the surface seemed to be restricted to the tumor micro-environment, while CD4 + T cells had a high expression of PD-1 also in lymphoid organs. Interestingly, we found that the levels of PD-1 were significantly higher on CD8+ T cells than on CD4+ T cells into the tumor micro- environment (p < 0.0001). Conclusions In conclusion, we demonstrated that the efficacy of immune check- point inhibitors might be strongly enhanced by their combination with cancer vaccines. PeptiCRAd was able to increase the number of antigen-specific T cells and PD-L1 blockade prevented their exhaus- tion, resulting in long-lasting immunological memory and increased median survival

Garbage Collection for Monitoring Parametric Properties

Parametric properties are behavioral properties over program events that depend on one or more parameters. Parameters are bound to concrete data or objects at runtime, which makes parametric properties particularly suitable for stating multi-object relationships or protocols. Monitoring parametric properties independently of the employed formalism involves slicing traces with respect to parameter instances and sending these slices to appropriate non- parametric monitor instances. The number of such instances is theoretically unbounded and tends to be enormous in practice, to an extent that how to efficiently manage monitor instances has become one of the most challenging problems in runtime verification. The previous formalism-independent approach was only able to do the obvious, namely to garbage collect monitor instances when all bound parameter objects were garbage collected. This led to pathological behaviors where unnecessary monitor instances were kept for the entire length of a program. This paper proposes a new approach to garbage collecting monitor instances. Unnecessary monitor instances are collected lazily to avoid creating undue overhead. This lazy collection, along with some careful engineering, has resulted in RV, the most efficient parametric monitoring system to date. Our evaluation shows that the average overhead of RV in the DaCapo benchmark is 15%, which is two times lower than that of JavaMOP and orders of magnitude lower than that of Tracematches.Supported in part by NSF grants CCF-0916893, CNS-0720512, and CCF-0448501, by NASA contract NNL08AA23C, and by an NSA grant, a UIUC Campus Research Board Award, and a Samsung SAIT grant.published or submitted for publicationnot peer reviewe

Towards Categorizing and Formalizing the JDK API

Formal specification of correct library usage is extremely useful, both for software developers and for the formal analysis tools they use, such as model checkers or runtime monitoring systems. Unfortunately, the process of creating formal specifications is time consuming, and, for the most part, even the libraries in greatest use, such as the Java Development Kit (JDK) standard library, are left wholly without formal specification. This paper presents a tool-supported approach to help writing formal specifications for Java libraries and creating documentation augmented with highlighting and formal specifications. The presented approach has been applied to systematically and completely formalize the runtime properties of three core and commonly used packages of the JDK API, namely java.io, java.lang and java.util, yielding 137 formal specifications. Indirectly, this paper also brings empirical evidence that parametric specifications may be sufficiently powerful to express virtually all desirable runtime properties of the JDK API, and that its informal documentation can be formalized.published or submitted for publicationnot peer reviewe

Efficient Formalism-Independent Monitoring of Parametric Properties

Efficient monitoring of parametric properties, in spite of increasingly growing interest thanks to applications such as testing and security, imposes a highly non-trivial challenge on monitoring approaches due to the potentially huge number of parameter instances. A few solutions have been proposed, but most of them compromise their expressiveness for performance or vice versa. In this paper, we propose a generic, in terms of specification formalisms, yet efficient, solution to monitoring parametric specifications. Our approach is based on a general semantics for slicing parametric traces and makes use of knowledge about the property to monitor. The needed knowledge is not specific to the underlying formalism and can be easily computed when generating monitoring code from the property. An extensive evaluation shows that the monitoring code generated by our algorithm is still faster than other state-of-art techniques optimized for particular logics or properties

Making runtime monitoring of parametric properties practical

Software reliability has become more important than ever in recent years, as a wide spectrum of software solutions are being used on various platforms. To this end, runtime monitoring is one of the most promising and feasible solutions for enhancing software reliability. In particular, runtime monitoring of parametric properties (parametric monitoring) has been receiving growing attention for its suitability in object-oriented systems. Despite many parametric monitoring approaches that have been proposed recently, they are still not widely used in real applications, implying that parametric monitoring is not sufficiently practical yet. In this dissertation, three perspectives for better practicality of parametric monitoring are proposed: expressiveness, efficiency, and scalability. A number of techniques on all three perspectives are developed and integrated to the JavaMOP framework, which is a formalism-independent, extensible runtime monitoring framework for parametric properties. One limitation in expressing parametric properties is that the first event must alway initiate all parameters. This limitation is removed in the proposed work to improve expressiveness of parametric monitoring. Further, a new logical formalism, PTCaRet, is introduced for describing properties of the call stack. As for efficiency, the `enable set optimization', the `indexing cache', and the `monitor garbage collection' are proposed for optimizing creation of monitors, access to monitors, and termination of monitors, respectively. In addition, several scalable parametric monitoring techniques are introduced. These techniques, for the first time, allow a large number of simultaneous parametric specifications to be monitored efficiently. The optimization techniques presented in this dissertation were implemented into the JavaMOP framework, yielding JavaMOP 3.0, the latest and most efficient version of JavaMOP. Thorough evaluations show that these techniques can improve runtime performance of JavaMOP by 3 times on average, and up to 63 times in some cases; as for memory usage, by 3 times on average. While Tracematches and the previous version of JavaMOP crashed on several cases due to out of memory errors, the newer version of JavaMOP did not crash on any case during the evaluations. Considering that the previous version of JavaMOP was one of the most efficient parametric monitoring frameworks in terms of runtime performance, the results presented in the dissertation can be argued significant