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Thread safe, MT-safe: Use a mutex for every single resource to guarantee the thread to be free of race conditions when those resources are accessed by multiple threads simultaneously. Thread safety guarantees usually also include design steps to prevent or limit the risk of different forms of deadlocks , as well as optimizations to maximize ...
Most CPUs are byte-addressable, where each unique memory address refers to an 8-bit byte. Most CPUs can access individual bytes from each memory address, but they generally cannot access larger units (16 bits, 32 bits, 64 bits and so on) without these units being "aligned" to a specific boundary (the x86 platform being a notable exception).
In computer programming, thread-local storage (TLS) is a memory management method that uses static or global memory local to a thread. The concept allows storage of data that appears to be global in a system with separate threads. Many systems impose restrictions on the size of the thread-local memory block, in fact often rather tight limits.
The memory model defined in the C11 and C++11 standards specify that a C or C++ program containing a data race has undefined behavior. [ 3 ] [ 4 ] A race condition can be difficult to reproduce and debug because the end result is nondeterministic and depends on the relative timing between interfering threads.
Dereferencing any of these variables could cause a segmentation fault: dereferencing the null pointer generally will cause a segfault, while reading from the wild pointer may instead result in random data but no segfault, and reading from the dangling pointer may result in valid data for a while, and then random data as it is overwritten.
Concurrent data structures are significantly more difficult to design and to verify as being correct than their sequential counterparts. The primary source of this additional difficulty is concurrency, exacerbated by the fact that threads must be thought of as being completely asynchronous: they are subject to operating system preemption, page faults, interrupts, and so on.
For this reason, exception handling (and RTTI) can be disabled in many C++ compilers, which may be useful for systems with very limited memory [25] (such as embedded systems). This second approach is also superior in terms of achieving thread safety [citation needed]. Other definitional and implementation schemes have been proposed as well.
The Message Passing Interface (MPI) is a portable message-passing standard designed to function on parallel computing architectures. [1] The MPI standard defines the syntax and semantics of library routines that are useful to a wide range of users writing portable message-passing programs in C, C++, and Fortran.