It is never OK to read something possibly modified in a different thread without synchronization. What level of synchronization is needed depends on what you are actually reading. For primitive types, you should have a look at atomic reads, e.g. in the form of std::atomic<bool>. The reason synchronization is always needed is that the processors … Read more
Since you haven’t specified which OS or language/library you are talking about, let me answer in a generic way. Conceptually they are the same. But usually they are implemented slightly differently Monitor Usually, the implementation of monitors is faster/light-weight, since it is designed for multi-threaded synchronization within the same process. Also, usually, it is provided … Read more
but I am puzzled why use word “the object’s monitor” instend of “the object’s lock”? See ulmangt’s answer for links that explain the term “monitor” as used in this context. Note that: “Monitors were invented by Per Brinch Hansen and C. A. R. Hoare, and were first implemented in Brinch Hansen’s Concurrent Pascal language.” (Source: … Read more
A monitor is mechanism to control concurrent access to an object. This allows you to do: Thread 1: public void a() { synchronized(someObject) { // do something (1) } } Thread 2: public void b() { synchronized(someObject) { // do something else (2) } } This prevents Threads 1 and 2 accessing the monitored (synchronized) … Read more
try ps huH p <PID_OF_U_PROCESS> | wc -l or htop
A Monitor is an object designed to be accessed from multiple threads. The member functions or methods of a monitor object will enforce mutual exclusion, so only one thread may be performing any action on the object at a given time. If one thread is currently executing a member function of the object then any … Read more