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deadlocks can be detected while the program is running by running cycle detection algorithms on the graph that denes the current use of resourcesdene
here are the conditions necessary for a deadlock to occur note that all of them are necessary and none is sufcient1 nite resources the resources are
at the end of this lecture and into the next lecture we will discuss the last major type of logical error that can occurwhen programming with threads
consider a large web-based database in some sense google is sort of like this there might be many users who want to read from the database but only a
when programming with threads there are three very common mistakes that programmers oftenmake1 locking twice depending on the system and type of lock
we have talked about blocking locks which voluntarily yield and spinlocks which just spin until they acquire the lock at rst it seems like spinlocks
now lets implement bounded producer-consumer with semaphores a coke machine which is initially emptysemaphore semmutex 1 binary semaphore for
for example by initializing a semaphore to 0 threads can wait for an event to occur and impose an ordering constraint similar to a monitor using
synchronization can be achieved by means other than locks and condition variables one alternative is semaphores a semaphore is used to regulate trafc
there is a very small amount of networking background required for project 2 in project 2 we want our computer or our host to request information
recall that condition variables are synchronization primitives that enable threads to wait until a particular condition occursgeneralizing the
now let us present an implementation of a producer-consumer system using condition variables this implementation worksdequeuelockawhile queue empty
what does it mean for something to be thread-safe by saying that x is thread-safe we mean that if multiple threads use x at the same time we dont
synchronization serves two purposes 1 to ensure safety for updates on shared data eg to avoid races conditions and 2 to coordinate and order actions
how could we implement locks no matter how we choose to implement them we must have some hardware support one possibility for implementing locks on a
locks also known as mutexes short for mutual exclusion locks provide mutual exclusion to shared data inside a critical session they are implemented
as we already know threadsmust ensure consistency otherwise race conditions non-deterministic results might happen now consider the too much milk
now we consider the following questions how can the parent process communicate with its child or how can children processes communicate with other
unix process apithe two most important function calls to use when programming with several processes are fork and exec fork creates a copy of current
processes and threads each have their place in multi-programming generally to hide latency and to maximize cpu utilization with the continuing spread
one reason to learn c and c is simply that so much software is written in these languages a related butmore fundamental reason is that c and c are
operating systems have evolved tremendously in the last few decades the first approach for building operating systems taken during the 40s through
the term operating system os is often misused it is common for example for people to speak of an os when they are in fact referring to an os and to a
in this project you will implement the chandy and misras cm algorithm using posix threads pthreads the algorithm is a distributed
a- in a table format compare between programmed io interrupt -driven io and direct memory access dma in terms of basic idea advantages