It might help to first understand why the word fork was used to name this function. Ever heard of a “fork on the road?” At a fork, the process has to split paths. First there is a single process executing normally until you reach the fork call. When fork is called, a new process is … Read more
This is well presented in The Little Book of Semaphores. n = the number of threads count = 0 mutex = Semaphore(1) barrier = Semaphore(0) mutex.wait() count = count + 1 mutex.signal() if count == n: barrier.signal() # unblock ONE thread barrier.wait() barrier.signal() # once we are unblocked, it’s our duty to unblock the next … Read more
It is sometimes thought that exceptfds is needed to detect errors, but that is a misconception. Errors will be flagged in readfds. Although POSIX requires it (and even calls the parameter errorfds), it depends on the OS whether errors are also flagged in exceptfds. Really, this parameter is only needed if you care about exceptional … Read more
I don’t see any reason to prefer bzero over memset. memset is a standard C function while bzero has never been a C standard function. The rationale is probably because you can achieve exactly the same functionality using memset function. Now regarding efficiency, compilers like gcc use builtin implementations for memset which switch to a … Read more
On Linux (with a reasonably recent kernel), you can get this information out of /sys: /sys/devices/system/cpu/cpu0/cache/ This directory has a subdirectory for each level of cache. Each of those directories contains the following files: coherency_line_size level number_of_sets physical_line_partition shared_cpu_list shared_cpu_map size type ways_of_associativity This gives you more information about the cache then you’d ever hope … Read more
The one comes from main() and the other three from every fork(). Notice that all three forks() are going to be executed. You might want to take a look at the ref: RETURN VALUE Upon successful completion, fork() shall return 0 to the child process and shall return the process ID of the child process … Read more
If the file is moved (in the same filesystem) or renamed, then the file handle remains open and can still be used to read and write the file. If the file is deleted, the file handle remains open and can still be used (This is not what some people expect). The file will not really … Read more