Since processes frequently needs to communicate with other processes therefore, there is a need for a well-structured communication, without using interrupts, among processes.
In operating systems, processes that are working together share some common
storage (main memory, file etc.) that each process can read and write. When two
or more processes are reading or writing some shared data and the final result
depends on who runs precisely when, are called race conditions. Concurrently
executing threads that share data need to synchronize their operations and
processing in order to avoid race condition on shared data. Only one ‘customer’
thread at a time should be allowed to examine and update the shared variable.
Race conditions are also possible in Operating Systems. If the ready queue is implemented as a linked list and if the ready queue is being manipulated during the handling of an interrupt, then interrupts must be disabled to prevent another interrupt before the first one completes. If interrupts are not disabled than the linked list could become corrupt.