A method for detecting a deadlock of a database management system and recovering from the deadlock includes: updating data stored in a first server and a second server; determining whether the database management system is in a deadlock state by comparing data of the first server with data of the second server; and recovering from the deadlock state by changing data of the first server or the second server so that the data of the first server and the second server are identical.

An apparatus in one embodiment includes at least one processing device comprising a processor coupled to a memory, with the at least one processing device being configured to maintain a replication journal for recording replication write requests in a storage system, to detect a failure impacting the replication journal, and to initiate recovery of the replication journal responsive to the detected failure. In conjunction with the recovery of the replication journal, the at least one processing device is further configured to maintain a lock contention table that characterizes lock contentions between address lock ranges required for the recovery of the replication journal and address lock ranges required by other write requests in the storage system, and to utilize the lock contention table to resolve one or more potential deadlocks that would otherwise prevent completion of the recovery of the replication journal. Other embodiments include methods and computer program products.

Techniques for managing threads involve acquiring respective runtime addresses and call information of a plurality of lock objects in a plurality of threads, and determining, from the plurality of lock objects, a first group of lock objects associated with first call information and a second group of lock objects associated with second call information different from the first call information. The techniques further involve providing an indication that a deadlock exists in the plurality of threads if it is determined that a first group of runtime addresses of the first group of lock objects overlaps with a second group of runtime addresses of the second group of lock objects. Accordingly, potential deadlocks in a plurality of threads can be analyzed, thereby avoiding the inability of the threads to proceed normally due to the deadlocks.

A method for thread-safe development of a computer program configured for parallel thread execution comprises maintaining a digital record of read or write access to a data object from each of a plurality of sibling threads executing on a computer system. Pursuant to each instance of read or write access from a given sibling thread, an entry comprising an indicator of the access type is added to the digital record. The method further comprises assessing the thread safety of the read or write access corresponding to each entry in the digital record and identifying one or more thread-unsafe instances of read or write access based on the assessment of thread safety.

The subject technology performs a locking operation on a first set of keys by a first statement of a first transaction. The subject technology determines that a conflict occurred between the first statement and a second transaction. The subject technology determines that the second transaction has yet to complete after a predetermined period of time. The subject technology performs a deadlock detection process where the subject technology stores a key and value in a table indicating the first transaction and the second transaction, detects, based at least in part on a graph traversal of the table starting from the first transaction, a cycle between the first transaction and the second transaction, and determines that the first transaction is a youngest transaction in the detected cycle. The subject technology ceases execution of the first transaction in response to the first transaction being a youngest transaction in a detected cycle.

An instruction sequencing unit in an out-of-order (OOO) processor includes a Most Favored Instruction (MFI) mechanism that designates an instruction as an MFI. The processing queues in the processor identify when they contain the MFI, and assures processing the MFI. The MFI remains the MFI until it is completed or is flushed, and which time the MFI mechanism selects the next MFI.

A method, a system, and a computer program product are provided for reducing message passing for contention detection in distributed SIP server environments. The method is implemented in a computer infrastructure having computer executable code tangibly embodied on a computer readable storage medium having programming instructions operable to determine that a first site is waiting for a first object locked by a second site. The programming instructions are further operable to determine that a third site is waiting for a second object locked by the first site, and to send a first probe to the second site to determine whether the second site is waiting. A second probe is received and indicates that a site is waiting for an object locked by the first site. The second probe further indicates a deadlock in a distributed server environment to be resolved.

Disclosed systems and methods incorporate a sound and maximal causal model with control flow information for maximum concurrency error detection in general multithreaded programs. The maximal causal model may be based on or integrated with the sequential consistency model, and form the basis for a formula including branch and order variables as first-order logical constraints solvable by an SMT solver for detection or prediction of concurrency errors. The disclosed systems and methods also relate to predictive trace analysis (PTA) for predicting generic concurrency properties using local traces (as opposed to a global trace) through the threads of a multithreaded program. By uniformly modeling violations of concurrency properties and the thread causality as constraints over events, and using an SMT solver, the systems and methods predict property violations allowed by the causal model.

Examples herein describe performing non-sequential DMA read and writes. Rather than storing data sequentially, a DMA engine can write data into memory using non-sequential memory addresses. A data processing engine (DPE) controller can submit a first job using first parameters that instruct the DMA engine to store data using a first non-sequential write pattern. The DPE controller can also submit a second job using second parameters that instruct the DMA engine to store data using a second, different non-sequential write pattern. In this manner, the DMA engine can switch to performing DMA writes using different non-sequential patterns. Similarly, the DMA engine can use non-sequential reads to retrieve data from memory. When performing a first DMA read, the DMA engine can retrieve data from memory using a first sequential pattern and then perform a second DMA read where data is retrieved from memory using a second non-sequential read pattern.

A data processing apparatus (100) executes threads and includes a general program counter (PC) (120) identifying an instruction to be executed for at least a subset of the threads. Each thread has a thread PC (184). The subset of threads has at least one lock parameter (188, 500-504) for tracking exclusive access to shared resources. In response to a first instruction executed for a thread, the processor (160) modifies the at least one lock parameter (188), (500-504) to indicate that the thread has gained exclusive access to the shared resource. In response to a second instruction, the processor modifies the at least one lock parameter (188, 500-504) to indicate that the thread no longer has exclusive access. A selector (110) selects one of the subset of threads based on the at least one lock parameter (188, 500-504) and sets the general PC (120) to the thread PC (184) of the selected thread.