actual the above conditions occured in resource allocation problem in OS

A deadlock occurs when two (or more) threads have created a situation where they are all blocking each other. Imagine that threads T1 and T2 need to acquire both resources A and B in order to do their work. If T1 acquires resource A, then T2 acquires resource B, T1 could then be waiting for resource B while T2 was waiting for resource A. In this case, both threads will wait indefinitely for the resource held by the other thread. These threads are said to be deadlocked.

Starvation occurs when a scheduler process (i.e. the operating system) refuses to give a particular thread any quantity of a particular resource (generally CPU). If there are too many high-priority threads, a lower priority thread may be starved. This can have negative impacts, though, particularly when the lower-priority thread has a lock on some resource.

Race conditions occur when two threads interact in a negatve (buggy) way depending on the exact order that their different instructions are executed. If one thread sets a global variable, for example, then a second thread reads and modifies that global variable, and the first thread reads the variable, the first thread may experience a bug because the variable has changed unexpectedly.