On Thu, Jan 30, 2003 at 09:59:12AM +0530, MAASK Group wrote: > Do applications using threads (like MySQL or PostgreSQL) have locking at > thread level for protecting the implicitly shared data section, etc?? Do > they use the semget(), semop() calls in linux?? It would be really great if > someone put light on our serach!!! This depends entirely on the threading library in use. There are three major threading libraries -- libpthreads (provided by glibc), NGPT (an add-on maintained by IBM), NPTL (new glibc/kernels .. see RH 8.1 betas). I recall there being another one .. linuxthreads or something like that. These various libraries use different techniques to expose POSIX thread semantics to programs on Linux (which uses a different task model than POSIX). There are also "home made" thread libraries, which have their own threading APIs and either use multiple processes with some IPC to synchronise the threads, or use a single process and non-blocking IO to provide the abstraction. In short: there is no simple answer. It depends in large part on the programs and libraries in use. -- "Sniff you jerks later." -- Captain Murphy
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